Implements virtio-based console, network and block servers. The block
server uses a thread so it's async, which is an improvement over the
old synchronous implementation (but a little more complex).
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
Documentation/lguest/lguest.c | 1201 ++++++++++++++++++++++++-----------------
1 file changed, 711 insertions(+), 490 deletions(-)
diff -r a7242b81747f Documentation/lguest/lguest.c
--- a/Documentation/lguest/lguest.c Wed Sep 26 14:48:31 2007 +1000
+++ b/Documentation/lguest/lguest.c Wed Sep 26 15:24:32 2007 +1000
@@ -32,7 +32,9 @@
#include <termios.h>
#include <getopt.h>
#include <zlib.h>
-/*L:110 We can ignore the 28 include files we need for this program, but I do
+#include <assert.h>
+#include <sched.h>
+/*L:110 We can ignore the 30 include files we need for this program, but I do
* want to draw attention to the use of kernel-style types.
*
* As Linus said, "C is a Spartan language, and so should your naming be." I
@@ -44,6 +46,12 @@ typedef uint16_t u16;
typedef uint16_t u16;
typedef uint8_t u8;
#include "linux/lguest_launcher.h"
+#include "linux/pci_ids.h"
+#include "linux/virtio_config.h"
+#include "linux/virtio_net.h"
+#include "linux/virtio_blk.h"
+#include "linux/virtio_console.h"
+#include "linux/virtio_ring.h"
#include "asm/e820.h"
/*:*/
@@ -55,6 +63,8 @@ typedef uint8_t u8;
#endif
/* We can have up to 256 pages for devices. */
#define DEVICE_PAGES 256
+/* This fits nicely in a single 4096-byte page. */
+#define VIRTQUEUE_NUM 127
/*L:120 verbose is both a global flag and a macro. The C preprocessor allows
* this, and although I wouldn't recommend it, it works quite nicely here. */
@@ -78,8 +88,17 @@ struct device_list
fd_set infds;
int max_infd;
+ /* Counter to assign interrupt numbers. */
+ unsigned int next_irq;
+
+ /* Counter to print out convenient device numbers. */
+ unsigned int device_num;
+
/* The descriptor page for the devices. */
- struct lguest_device_desc *descs;
+ u8 *descpage;
+
+ /* The tail of the last descriptor. */
+ unsigned int desc_used;
/* A single linked list of devices. */
struct device *dev;
@@ -87,30 +106,87 @@ struct device_list
struct device **lastdev;
};
+/* The list of Guest devices, based on command line arguments. */
+static struct device_list devices;
+
/* The device structure describes a single device. */
struct device
{
/* The linked-list pointer. */
struct device *next;
- /* The descriptor for this device, as mapped into the Guest. */
+
+ /* The this device's descriptor, as mapped into the Guest. */
struct lguest_device_desc *desc;
- /* The memory page(s) of this device, if any. Also mapped in Guest. */
- void *mem;
+
+ /* The name of this device, for --verbose. */
+ const char *name;
/* If handle_input is set, it wants to be called when this file
* descriptor is ready. */
int fd;
bool (*handle_input)(int fd, struct device *me);
- /* If handle_output is set, it wants to be called when the Guest sends
- * DMA to this key. */
- unsigned long watch_key;
- u32 (*handle_output)(int fd, const struct iovec *iov,
- unsigned int num, struct device *me);
+ /* Any queues attached to this device */
+ struct virtqueue *vq;
/* Device-specific data. */
void *priv;
};
+
+/* The virtqueue structure describes a queue attached to a device. */
+struct virtqueue
+{
+ struct virtqueue *next;
+
+ /* Which device owns me. */
+ struct device *dev;
+
+ /* The configuration for this queue. */
+ struct lguest_vqconfig config;
+
+ /* The actual ring of buffers. */
+ struct vring vring;
+
+ /* Last available index we saw. */
+ u16 last_avail_idx;
+
+ /* The routine to call when the Guest pings us. */
+ void (*handle_output)(int fd, struct virtqueue *me);
+};
+
+/* Since guest is UP and we don't run at the same time, we don't need barriers.
+ * But I include them in the code in case others copy it. */
+#define wmb()
+
+/* Convert an iovec element to the given type.
+ *
+ * This is a fairly ugly trick: we need to know the size of the type and
+ * alignment requirement to check the pointer is kosher. It's also nice to
+ * have the name of the type in case we report failure.
+ *
+ * Typing those three things all the time is cumbersome and error prone, so we
+ * have a macro which sets them all up and passes to the real function. */
+#define convert(iov, type) \
+ ((type *)_convert((iov), sizeof(type), __alignof__(type), #type))
+
+static void *_convert(struct iovec *iov, size_t size, size_t align,
+ const char *name)
+{
+ if (iov->iov_len != size)
+ errx(1, "Bad iovec size %zu for %s", iov->iov_len, name);
+ if ((unsigned long)iov->iov_base % align != 0)
+ errx(1, "Bad alignment %p for %s", iov->iov_base, name);
+ return iov->iov_base;
+}
+
+/* The virtio configuration space is defined to be little-endian. x86 is
+ * little-endian too, but it's nice to be explicit so we have these helpers. */
+#define cpu_to_le16(v16) (v16)
+#define cpu_to_le32(v32) (v32)
+#define cpu_to_le64(v64) (v64)
+#define le16_to_cpu(v16) (v16)
+#define le32_to_cpu(v32) (v32)
+#define le64_to_cpu(v32) (v64)
/*L:100 The Launcher code itself takes us out into userspace, that scary place
* where pointers run wild and free! Unfortunately, like most userspace
@@ -486,11 +562,11 @@ static int tell_kernel(unsigned long pgd
}
/*:*/
-static void set_fd(int fd, struct device_list *devices)
-{
- FD_SET(fd, &devices->infds);
- if (fd > devices->max_infd)
- devices->max_infd = fd;
+static void add_device_fd(int fd)
+{
+ FD_SET(fd, &devices.infds);
+ if (fd > devices.max_infd)
+ devices.max_infd = fd;
}
/*L:200
@@ -508,18 +584,18 @@ static void set_fd(int fd, struct device
*
* This, of course, is merely a different *kind* of icky.
*/
-static void wake_parent(int pipefd, int lguest_fd, struct device_list *devices)
+static void wake_parent(int pipefd, int lguest_fd)
{
/* Add the pipe from the Launcher to the fdset in the device_list, so
* we watch it, too. */
- set_fd(pipefd, devices);
+ add_device_fd(pipefd);
for (;;) {
- fd_set rfds = devices->infds;
+ fd_set rfds = devices.infds;
unsigned long args[] = { LHREQ_BREAK, 1 };
/* Wait until input is ready from one of the devices. */
- select(devices->max_infd+1, &rfds, NULL, NULL, NULL);
+ select(devices.max_infd+1, &rfds, NULL, NULL, NULL);
/* Is it a message from the Launcher? */
if (FD_ISSET(pipefd, &rfds)) {
int ignorefd;
@@ -530,14 +606,14 @@ static void wake_parent(int pipefd, int
/* Otherwise it's telling us there's a problem with one
* of the devices, and we should ignore that file
* descriptor from now on. */
- FD_CLR(ignorefd, &devices->infds);
+ FD_CLR(ignorefd, &devices.infds);
} else /* Send LHREQ_BREAK command. */
write(lguest_fd, args, sizeof(args));
}
}
/* This routine just sets up a pipe to the Waker process. */
-static int setup_waker(int lguest_fd, struct device_list *device_list)
+static int setup_waker(int lguest_fd)
{
int pipefd[2], child;
@@ -551,7 +627,7 @@ static int setup_waker(int lguest_fd, st
if (child == 0) {
/* Close the "writing" end of our copy of the pipe */
close(pipefd[1]);
- wake_parent(pipefd[0], lguest_fd, device_list);
+ wake_parent(pipefd[0], lguest_fd);
}
/* Close the reading end of our copy of the pipe. */
close(pipefd[0]);
@@ -574,71 +650,13 @@ static void *_check_pointer(unsigned lon
/* We have to separately check addr and addr+size, because size could
* be huge and addr + size might wrap around. */
if (addr >= guest_limit || addr + size >= guest_limit)
- errx(1, "%s:%i: Invalid address %li", __FILE__, line, addr);
+ errx(1, "%s:%i: Invalid address %#lx", __FILE__, line, addr);
/* We return a pointer for the caller's convenience, now we know it's
* safe to use. */
return from_guest_phys(addr);
}
/* A macro which transparently hands the line number to the real function. */
#define check_pointer(addr,size) _check_pointer(addr, size, __LINE__)
-
-/* The Guest has given us the address of a "struct lguest_dma". We check it's
- * OK and convert it to an iovec (which is a simple array of ptr/size
- * pairs). */
-static u32 *dma2iov(unsigned long dma, struct iovec iov[], unsigned *num)
-{
- unsigned int i;
- struct lguest_dma *udma;
-
- /* First we make sure that the array memory itself is valid. */
- udma = check_pointer(dma, sizeof(*udma));
- /* Now we check each element */
- for (i = 0; i < LGUEST_MAX_DMA_SECTIONS; i++) {
- /* A zero length ends the array. */
- if (!udma->len[i])
- break;
-
- iov[i].iov_base = check_pointer(udma->addr[i], udma->len[i]);
- iov[i].iov_len = udma->len[i];
- }
- *num = i;
-
- /* We return the pointer to where the caller should write the amount of
- * the buffer used. */
- return &udma->used_len;
-}
-
-/* This routine gets a DMA buffer from the Guest for a given key, and converts
- * it to an iovec array. It returns the interrupt the Guest wants when we're
- * finished, and a pointer to the "used_len" field to fill in. */
-static u32 *get_dma_buffer(int fd, void *key,
- struct iovec iov[], unsigned int *num, u32 *irq)
-{
- unsigned long buf[] = { LHREQ_GETDMA, to_guest_phys(key) };
- unsigned long udma;
- u32 *res;
-
- /* Ask the kernel for a DMA buffer corresponding to this key. */
- udma = write(fd, buf, sizeof(buf));
- /* They haven't registered any, or they're all used? */
- if (udma == (unsigned long)-1)
- return NULL;
-
- /* Convert it into our iovec array */
- res = dma2iov(udma, iov, num);
- /* The kernel stashes irq in ->used_len to get it out to us. */
- *irq = *res;
- /* Return a pointer to ((struct lguest_dma *)udma)->used_len. */
- return res;
-}
-
-/* This is a convenient routine to send the Guest an interrupt. */
-static void trigger_irq(int fd, u32 irq)
-{
- unsigned long buf[] = { LHREQ_IRQ, irq };
- if (write(fd, buf, sizeof(buf)) != 0)
- err(1, "Triggering irq %i", irq);
-}
/* This simply sets up an iovec array where we can put data to be discarded.
* This happens when the Guest doesn't want or can't handle the input: we have
@@ -652,6 +670,121 @@ static void discard_iovec(struct iovec *
iov->iov_len = sizeof(discard_buf);
}
+/* This function returns the next descriptor in the chain, or vq->vring.num. */
+static unsigned next_desc(struct virtqueue *vq, unsigned int i)
+{
+ unsigned int next;
+
+ /* If this descriptor says it doesn't chain, we're done. */
+ if (!(vq->vring.desc[i].flags & VRING_DESC_F_NEXT))
+ return vq->vring.num;
+
+ /* Check they're not leading us off end of descriptors. */
+ next = vq->vring.desc[i].next;
+ /* Make sure compiler knows to grab that: we don't want it changing! */
+ wmb();
+
+ if (next >= vq->vring.num)
+ errx(1, "Desc next is %u", next);
+
+ return next;
+}
+
+/* This looks in the virtqueue and for the first available buffer, and converts
+ * it to an iovec for convenient access. Since descriptors consist of some
+ * number of output then some number of input descriptors, it's actually two
+ * iovecs, but we pack them into one and note how many of each there were.
+ *
+ * This function returns the descriptor number found, or vq->vring.num (which
+ * is never a valid descriptor number) if none was found. */
+static unsigned get_vq_desc(struct virtqueue *vq,
+ struct iovec iov[],
+ unsigned int *out_num, unsigned int *in_num)
+{
+ unsigned int i, head;
+
+ /* Check it isn't doing very strange things with descriptor numbers. */
+ if ((u16)(vq->vring.avail->idx - vq->last_avail_idx) > vq->vring.num)
+ errx(1, "Guest moved used index from %u to %u",
+ vq->last_avail_idx, vq->vring.avail->idx);
+
+ /* If there's nothing new since last we looked, return invalid. */
+ if (vq->vring.avail->idx == vq->last_avail_idx)
+ return vq->vring.num;
+
+ /* Grab the next descriptor number they're advertising, and increment
+ * the index we've seen. */
+ head = vq->vring.avail->ring[vq->last_avail_idx++ % vq->vring.num];
+
+ /* If their number is silly, that's a fatal mistake. */
+ if (head >= vq->vring.num)
+ errx(1, "Guest says index %u is available", head);
+
+ /* When we start there are none of either input nor output. */
+ *out_num = *in_num = 0;
+
+ i = head;
+ do {
+ /* Grab the first descriptor, and check it's OK. */
+ iov[*out_num + *in_num].iov_len = vq->vring.desc[i].len;
+ iov[*out_num + *in_num].iov_base
+ = check_pointer(vq->vring.desc[i].addr,
+ vq->vring.desc[i].len);
+ /* If this is an input descriptor, increment that count. */
+ if (vq->vring.desc[i].flags & VRING_DESC_F_WRITE)
+ (*in_num)++;
+ else {
+ /* If it's an output descriptor, they're all supposed
+ * to come before any input descriptors. */
+ if (*in_num)
+ errx(1, "Descriptor has out after in");
+ (*out_num)++;
+ }
+
+ /* If we've got too many, that implies a descriptor loop. */
+ if (*out_num + *in_num > vq->vring.num)
+ errx(1, "Looped descriptor");
+ } while ((i = next_desc(vq, i)) != vq->vring.num);
+
+ return head;
+}
+
+/* Once we've used one of their buffers, we tell them about it. We'll then
+ * want to send them an interrupt, using trigger_irq(). */
+static void add_used(struct virtqueue *vq, unsigned int head, int len)
+{
+ struct vring_used_elem *used;
+
+ /* Get a pointer to the next entry in the used ring. */
+ used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num];
+ used->id = head;
+ used->len = len;
+ /* Make sure buffer is written before we update index. */
+ wmb();
+ vq->vring.used->idx++;
+}
+
+/* This actually sends the interrupt for this virtqueue */
+static void trigger_irq(int fd, struct virtqueue *vq)
+{
+ unsigned long buf[] = { LHREQ_IRQ, vq->config.irq };
+
+ if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+ return;
+
+ /* Send the Guest an interrupt tell them we used something up. */
+ if (write(fd, buf, sizeof(buf)) != 0)
+ err(1, "Triggering irq %i", vq->config.irq);
+}
+
+/* And here's the combo meal deal. Supersize me! */
+static void add_used_and_trigger(int fd, struct virtqueue *vq,
+ unsigned int head, int len)
+{
+ add_used(vq, head, len);
+ trigger_irq(fd, vq);
+}
+
/* Here is the input terminal setting we save, and the routine to restore them
* on exit so the user can see what they type next. */
static struct termios orig_term;
@@ -672,38 +805,37 @@ struct console_abort
/* This is the routine which handles console input (ie. stdin). */
static bool handle_console_input(int fd, struct device *dev)
{
- u32 irq = 0, *lenp;
int len;
- unsigned int num;
- struct iovec iov[LGUEST_MAX_DMA_SECTIONS];
+ unsigned int head, in_num, out_num;
+ struct iovec iov[dev->vq->vring.num];
struct console_abort *abort = dev->priv;
- /* First we get the console buffer from the Guest. The key is dev->mem
- * which was set to 0 in setup_console(). */
- lenp = get_dma_buffer(fd, dev->mem, iov, &num, &irq);
- if (!lenp) {
- /* If it's not ready for input, warn and set up to discard. */
- warn("console: no dma buffer!");
- discard_iovec(iov, &num);
- }
+ /* First we need a console buffer from the Guests's input virtqueue. */
+ head = get_vq_desc(dev->vq, iov, &out_num, &in_num);
+ if (head == dev->vq->vring.num) {
+ /* If they're not ready for input, we warn and set up to
+ * discard. */
+ warnx("console: no dma buffer!");
+ discard_iovec(iov, &in_num);
+ } else if (out_num)
+ errx(1, "Output buffers in console in queue?");
/* This is why we convert to iovecs: the readv() call uses them, and so
* it reads straight into the Guest's buffer. */
- len = readv(dev->fd, iov, num);
+ len = readv(dev->fd, iov, in_num);
if (len <= 0) {
/* This implies that the console is closed, is /dev/null, or
- * something went terribly wrong. We still go through the rest
- * of the logic, though, especially the exit handling below. */
+ * something went terribly wrong. */
warnx("Failed to get console input, ignoring console.");
- len = 0;
- }
-
- /* If we read the data into the Guest, fill in the length and send the
- * interrupt. */
- if (lenp) {
- *lenp = len;
- trigger_irq(fd, irq);
- }
+ /* Put the input terminal back and return failure (meaning,
+ * don't call us again). */
+ restore_term();
+ return false;
+ }
+
+ /* If we actually read the data into the Guest, tell them about it. */
+ if (head != dev->vq->vring.num)
+ add_used_and_trigger(fd, dev->vq, head, len);
/* Three ^C within one second? Exit.
*
@@ -732,202 +864,137 @@ static bool handle_console_input(int fd,
/* Any other key resets the abort counter. */
abort->count = 0;
- /* Now, if we didn't read anything, put the input terminal back and
- * return failure (meaning, don't call us again). */
- if (!len) {
- restore_term();
- return false;
- }
/* Everything went OK! */
return true;
}
-/* Handling console output is much simpler than input. */
-static u32 handle_console_output(int fd, const struct iovec *iov,
- unsigned num, struct device*dev)
-{
- /* Whatever the Guest sends, write it to standard output. Return the
- * number of bytes written. */
- return writev(STDOUT_FILENO, iov, num);
-}
-
-/* Guest->Host network output is also pretty easy. */
-static u32 handle_tun_output(int fd, const struct iovec *iov,
- unsigned num, struct device *dev)
-{
- /* We put a flag in the "priv" pointer of the network device, and set
- * it as soon as we see output. We'll see why in handle_tun_input() */
- *(bool *)dev->priv = true;
- /* Whatever packet the Guest sent us, write it out to the tun
- * device. */
- return writev(dev->fd, iov, num);
-}
-
-/* This matches the peer_key() in lguest_net.c. The key for any given slot
- * is the address of the network device's page plus 4 * the slot number. */
-static unsigned long peer_offset(unsigned int peernum)
-{
- return 4 * peernum;
-}
-
-/* This is where we handle a packet coming in from the tun device */
+/* Handling output for console is simple: we just get all the output buffers
+ * and write them to stdout. */
+static void handle_console_output(int fd, struct virtqueue *vq)
+{
+ unsigned int head, out, in;
+ int len;
+ struct iovec iov[vq->vring.num];
+
+ /* Keep getting output buffers from the Guest until we run out. */
+ while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) {
+ if (in)
+ errx(1, "Input buffers in output queue?");
+ len = writev(STDOUT_FILENO, iov, out);
+ add_used_and_trigger(fd, vq, head, len);
+ }
+}
+
+/* Handling output for network is also simple: we get all the output buffers
+ * and write them (ignoring the first element) to this device's file descriptor
+ * (stdout). */
+static void handle_net_output(int fd, struct virtqueue *vq)
+{
+ unsigned int head, out, in;
+ int len;
+ struct iovec iov[vq->vring.num];
+
+ /* Keep getting output buffers from the Guest until we run out. */
+ while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) {
+ if (in)
+ errx(1, "Input buffers in output queue?");
+ /* Check header, but otherwise ignore it (we said we supported
+ * no features). */
+ (void)convert(&iov[0], struct virtio_net_hdr);
+ len = writev(vq->dev->fd, iov+1, out-1);
+ add_used_and_trigger(fd, vq, head, len);
+ }
+}
+
+/* This is where we handle a packet coming in from the tun device to our
+ * Guest. */
static bool handle_tun_input(int fd, struct device *dev)
{
- u32 irq = 0, *lenp;
+ unsigned int head, in_num, out_num;
int len;
- unsigned num;
- struct iovec iov[LGUEST_MAX_DMA_SECTIONS];
-
- /* First we get a buffer the Guest has bound to its key. */
- lenp = get_dma_buffer(fd, dev->mem+peer_offset(NET_PEERNUM), iov, &num,
- &irq);
- if (!lenp) {
+ struct iovec iov[dev->vq->vring.num];
+ struct virtio_net_hdr *hdr;
+
+ /* First we need a network buffer from the Guests's recv virtqueue. */
+ head = get_vq_desc(dev->vq, iov, &out_num, &in_num);
+ if (head == dev->vq->vring.num) {
/* Now, it's expected that if we try to send a packet too
- * early, the Guest won't be ready yet. This is why we set a
- * flag when the Guest sends its first packet. If it's sent a
- * packet we assume it should be ready to receive them.
- *
- * Actually, this is what the status bits in the descriptor are
- * for: we should *use* them. FIXME! */
- if (*(bool *)dev->priv)
+ * early, the Guest won't be ready yet. Wait until the device
+ * status says it's ready. */
+ /* FIXME: Actually want DRIVER_ACTIVE here. */
+ if (dev->desc->status & VIRTIO_CONFIG_S_DRIVER_OK)
warn("network: no dma buffer!");
- discard_iovec(iov, &num);
- }
+ discard_iovec(iov, &in_num);
+ } else if (out_num)
+ errx(1, "Output buffers in network recv queue?");
+
+ /* First element is the header: we set it to 0 (no features). */
+ hdr = convert(&iov[0], struct virtio_net_hdr);
+ hdr->flags = 0;
+ hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
/* Read the packet from the device directly into the Guest's buffer. */
- len = readv(dev->fd, iov, num);
+ len = readv(dev->fd, iov+1, in_num-1);
if (len <= 0)
err(1, "reading network");
- /* Write the used_len, and trigger the interrupt for the Guest */
- if (lenp) {
- *lenp = len;
- trigger_irq(fd, irq);
- }
+ /* If we actually read the data into the Guest, tell them about it. */
+ if (head != dev->vq->vring.num)
+ add_used_and_trigger(fd, dev->vq, head, sizeof(*hdr) + len);
+
verbose("tun input packet len %i [%02x %02x] (%s)\n", len,
- ((u8 *)iov[0].iov_base)[0], ((u8 *)iov[0].iov_base)[1],
- lenp ? "sent" : "discarded");
+ ((u8 *)iov[1].iov_base)[0], ((u8 *)iov[1].iov_base)[1],
+ head != dev->vq->vring.num ? "sent" : "discarded");
+
/* All good. */
return true;
}
-/* The last device handling routine is block output: the Guest has sent a DMA
- * to the block device. It will have placed the command it wants in the
- * "struct lguest_block_page". */
-static u32 handle_block_output(int fd, const struct iovec *iov,
- unsigned num, struct device *dev)
-{
- struct lguest_block_page *p = dev->mem;
- u32 irq, *lenp;
- unsigned int len, reply_num;
- struct iovec reply[LGUEST_MAX_DMA_SECTIONS];
- off64_t device_len, off = (off64_t)p->sector * 512;
-
- /* First we extract the device length from the dev->priv pointer. */
- device_len = *(off64_t *)dev->priv;
-
- /* We first check that the read or write is within the length of the
- * block file. */
- if (off >= device_len)
- errx(1, "Bad offset %llu vs %llu", off, device_len);
- /* Move to the right location in the block file. This shouldn't fail,
- * but best to check. */
- if (lseek64(dev->fd, off, SEEK_SET) != off)
- err(1, "Bad seek to sector %i", p->sector);
-
- verbose("Block: %s at offset %llu\n", p->type ? "WRITE" : "READ", off);
-
- /* They were supposed to bind a reply buffer at key equal to the start
- * of the block device memory. We need this to tell them when the
- * request is finished. */
- lenp = get_dma_buffer(fd, dev->mem, reply, &reply_num, &irq);
- if (!lenp)
- err(1, "Block request didn't give us a dma buffer");
-
- if (p->type) {
- /* A write request. The DMA they sent contained the data, so
- * write it out. */
- len = writev(dev->fd, iov, num);
- /* Grr... Now we know how long the "struct lguest_dma" they
- * sent was, we make sure they didn't try to write over the end
- * of the block file (possibly extending it). */
- if (off + len > device_len) {
- /* Trim it back to the correct length */
- ftruncate64(dev->fd, device_len);
- /* Die, bad Guest, die. */
- errx(1, "Write past end %llu+%u", off, len);
+/* This is the generic routine we call when the Guest uses LHCALL_NOTIFY. */
+static void handle_output(int fd, unsigned long addr)
+{
+ struct device *i;
+ struct virtqueue *vq;
+
+ /* Check each virtqueue. */
+ for (i = devices.dev; i; i = i->next) {
+ for (vq = i->vq; vq; vq = vq->next) {
+ if (vq->config.pfn == addr/getpagesize()
+ && vq->handle_output) {
+ verbose("Output to %s\n", vq->dev->name);
+ vq->handle_output(fd, vq);
+ return;
+ }
}
- /* The reply length is 0: we just send back an empty DMA to
- * interrupt them and tell them the write is finished. */
- *lenp = 0;
- } else {
- /* A read request. They sent an empty DMA to start the
- * request, and we put the read contents into the reply
- * buffer. */
- len = readv(dev->fd, reply, reply_num);
- *lenp = len;
- }
-
- /* The result is 1 (done), 2 if there was an error (short read or
- * write). */
- p->result = 1 + (p->bytes != len);
- /* Now tell them we've used their reply buffer. */
- trigger_irq(fd, irq);
-
- /* We're supposed to return the number of bytes of the output buffer we
- * used. But the block device uses the "result" field instead, so we
- * don't bother. */
- return 0;
-}
-
-/* This is the generic routine we call when the Guest sends some DMA out. */
-static void handle_output(int fd, unsigned long dma, unsigned long key,
- struct device_list *devices)
-{
- struct device *i;
- u32 *lenp;
- struct iovec iov[LGUEST_MAX_DMA_SECTIONS];
- unsigned num = 0;
-
- /* Convert the "struct lguest_dma" they're sending to a "struct
- * iovec". */
- lenp = dma2iov(dma, iov, &num);
-
- /* Check each device: if they expect output to this key, tell them to
- * handle it. */
- for (i = devices->dev; i; i = i->next) {
- if (i->handle_output && key == i->watch_key) {
- /* We write the result straight into the used_len field
- * for them. */
- *lenp = i->handle_output(fd, iov, num, i);
- return;
- }
- }
-
- /* This can happen: the kernel sends any SEND_DMA which doesn't match
- * another Guest to us. It could be that another Guest just left a
- * network, for example. But it's unusual. */
- warnx("Pending dma %p, key %p", (void *)dma, (void *)key);
+ }
+
+ /* Early console write is done using notify on a nul-terminated string
+ * in Guest memory. */
+ if (addr >= guest_limit)
+ errx(1, "Bad NOTIFY %#lx", addr);
+
+ write(STDOUT_FILENO, from_guest_phys(addr),
+ strnlen(from_guest_phys(addr), guest_limit - addr));
}
/* This is called when the waker wakes us up: check for incoming file
* descriptors. */
-static void handle_input(int fd, struct device_list *devices)
+static void handle_input(int fd)
{
/* select() wants a zeroed timeval to mean "don't wait". */
struct timeval poll = { .tv_sec = 0, .tv_usec = 0 };
for (;;) {
struct device *i;
- fd_set fds = devices->infds;
+ fd_set fds = devices.infds;
/* If nothing is ready, we're done. */
- if (select(devices->max_infd+1, &fds, NULL, NULL, &poll) == 0)
+ if (select(devices.max_infd+1, &fds, NULL, NULL, &poll) == 0)
break;
/* Otherwise, call the device(s) which have readable
* file descriptors and a method of handling them. */
- for (i = devices->dev; i; i = i->next) {
+ for (i = devices.dev; i; i = i->next) {
if (i->handle_input && FD_ISSET(i->fd, &fds)) {
/* If handle_input() returns false, it means we
* should no longer service it.
@@ -936,7 +1003,7 @@ static void handle_input(int fd, struct
/* Clear it from the set of input file
* descriptors kept at the head of the
* device list. */
- FD_CLR(i->fd, &devices->infds);
+ FD_CLR(i->fd, &devices.infds);
/* Tell waker to ignore it too... */
write(waker_fd, &i->fd, sizeof(i->fd));
}
@@ -953,43 +1020,93 @@ static void handle_input(int fd, struct
* routines to allocate them.
*
* This routine allocates a new "struct lguest_device_desc" from descriptor
- * table in the devices array just above the Guest's normal memory. */
-static struct lguest_device_desc *
-new_dev_desc(struct lguest_device_desc *descs,
- u16 type, u16 features, u16 num_pages)
-{
- unsigned int i;
-
- for (i = 0; i < LGUEST_MAX_DEVICES; i++) {
- if (!descs[i].type) {
- descs[i].type = type;
- descs[i].features = features;
- descs[i].num_pages = num_pages;
- /* If they said the device needs memory, we allocate
- * that now. */
- if (num_pages) {
- unsigned long pa;
- pa = to_guest_phys(get_pages(num_pages));
- descs[i].pfn = pa / getpagesize();
- }
- return &descs[i];
- }
- }
- errx(1, "too many devices");
-}
-
-/* This monster routine does all the creation and setup of a new device,
- * including caling new_dev_desc() to allocate the descriptor and device
- * memory. */
-static struct device *new_device(struct device_list *devices,
- u16 type, u16 num_pages, u16 features,
- int fd,
- bool (*handle_input)(int, struct device *),
- unsigned long watch_off,
- u32 (*handle_output)(int,
- const struct iovec *,
- unsigned,
- struct device *))
+ * table just above the Guest's normal memory. It returns a pointer to that
+ * descriptor. */
+static struct lguest_device_desc *new_dev_desc(u16 type)
+{
+ struct lguest_device_desc *d;
+
+ /* We only have one page for all the descriptors. */
+ if (devices.desc_used + sizeof(*d) > getpagesize())
+ errx(1, "Too many devices");
+
+ /* We don't need to set config_len or status: page is 0 already. */
+ d = (void *)devices.descpage + devices.desc_used;
+ d->type = type;
+ devices.desc_used += sizeof(*d);
+
+ return d;
+}
+
+/* Each device descriptor is followed by some configuration information.
+ * The first byte is a "status" byte for the Guest to report what's happening.
+ * After that are fields: u8 type, u8 len, [... len bytes...].
+ *
+ * This routine adds a new field to an existing device's descriptor. It only
+ * works for the last device, but that's OK because that's how we use it. */
+static void add_desc_field(struct device *dev, u8 type, u8 len, const void *c)
+{
+ /* This is the last descriptor, right? */
+ assert(devices.descpage + devices.desc_used
+ == (u8 *)(dev->desc + 1) + dev->desc->config_len);
+
+ /* We only have one page of device descriptions. */
+ if (devices.desc_used + 2 + len > getpagesize())
+ errx(1, "Too many devices");
+
+ /* Copy in the new config header: type then length. */
+ devices.descpage[devices.desc_used++] = type;
+ devices.descpage[devices.desc_used++] = len;
+ memcpy(devices.descpage + devices.desc_used, c, len);
+ devices.desc_used += len;
+
+ /* Update the device descriptor length: two byte head then data. */
+ dev->desc->config_len += 2 + len;
+}
+
+/* This routine adds a virtqueue to a device. We specify how many descriptors
+ * the virtqueue is to have. */
+static void add_virtqueue(struct device *dev, unsigned int num_descs,
+ void (*handle_output)(int fd, struct virtqueue *me))
+{
+ unsigned int pages;
+ struct virtqueue **i, *vq = malloc(sizeof(*vq));
+ void *p;
+
+ /* First we need some pages for this virtqueue. */
+ pages = (vring_size(num_descs) + getpagesize() - 1) / getpagesize();
+ p = get_pages(pages);
+
+ /* Initialize the configuration. */
+ vq->config.num = num_descs;
+ vq->config.irq = devices.next_irq++;
+ vq->config.pfn = to_guest_phys(p) / getpagesize();
+
+ /* Initialize the vring. */
+ vring_init(&vq->vring, num_descs, p);
+
+ /* Add the configuration information to this device's descriptor. */
+ add_desc_field(dev, VIRTIO_CONFIG_F_VIRTQUEUE,
+ sizeof(vq->config), &vq->config);
+
+ /* Add to tail of list, so dev->vq is first vq, dev->vq->next is
+ * second. */
+ for (i = &dev->vq; *i; i = &(*i)->next);
+ *i = vq;
+
+ /* Link virtqueue back to device. */
+ vq->dev = dev;
+
+ /* Set up handler. */
+ vq->handle_output = handle_output;
+ if (!handle_output)
+ vq->vring.used->flags = VRING_USED_F_NO_NOTIFY;
+}
+
+/* This routine does all the creation and setup of a new device, including
+ * caling new_dev_desc() to allocate the descriptor and device memory. */
+static struct device *new_device(const char *name, u16 type, int fd,
+ bool (*handle_input)(int, struct device *))
{
struct device *dev = malloc(sizeof(*dev));
@@ -997,27 +1114,25 @@ static struct device *new_device(struct
* easier, but the user expects the devices to be arranged on the bus
* in command-line order. The first network device on the command line
* is eth0, the first block device /dev/lgba, etc. */
- *devices->lastdev = dev;
+ *devices.lastdev = dev;
dev->next = NULL;
- devices->lastdev = &dev->next;
+ devices.lastdev = &dev->next;
/* Now we populate the fields one at a time. */
dev->fd = fd;
/* If we have an input handler for this file descriptor, then we add it
* to the device_list's fdset and maxfd. */
if (handle_input)
- set_fd(dev->fd, devices);
- dev->desc = new_dev_desc(devices->descs, type, features, num_pages);
- dev->mem = from_guest_phys(dev->desc->pfn * getpagesize());
+ add_device_fd(dev->fd);
+ dev->desc = new_dev_desc(type);
dev->handle_input = handle_input;
- dev->watch_key = to_guest_phys(dev->mem) + watch_off;
- dev->handle_output = handle_output;
+ dev->name = name;
return dev;
}
/* Our first setup routine is the console. It's a fairly simple device, but
* UNIX tty handling makes it uglier than it could be. */
-static void setup_console(struct device_list *devices)
+static void setup_console(void)
{
struct device *dev;
@@ -1033,127 +1148,38 @@ static void setup_console(struct device_
atexit(restore_term);
}
- /* We don't currently require any memory for the console, so we ask for
- * 0 pages. */
- dev = new_device(devices, LGUEST_DEVICE_T_CONSOLE, 0, 0,
- STDIN_FILENO, handle_console_input,
- LGUEST_CONSOLE_DMA_KEY, handle_console_output);
+ dev = new_device("console", VIRTIO_ID_CONSOLE,
+ STDIN_FILENO, handle_console_input);
/* We store the console state in dev->priv, and initialize it. */
dev->priv = malloc(sizeof(struct console_abort));
((struct console_abort *)dev->priv)->count = 0;
- verbose("device %p: console\n",
- (void *)(dev->desc->pfn * getpagesize()));
-}
-
-/* Setting up a block file is also fairly straightforward. */
-static void setup_block_file(const char *filename, struct device_list *devices)
-{
- int fd;
- struct device *dev;
- off64_t *device_len;
- struct lguest_block_page *p;
-
- /* We open with O_LARGEFILE because otherwise we get stuck at 2G. We
- * open with O_DIRECT because otherwise our benchmarks go much too
- * fast. */
- fd = open_or_die(filename, O_RDWR|O_LARGEFILE|O_DIRECT);
-
- /* We want one page, and have no input handler (the block file never
- * has anything interesting to say to us). Our timing will be quite
- * random, so it should be a reasonable randomness source. */
- dev = new_device(devices, LGUEST_DEVICE_T_BLOCK, 1,
- LGUEST_DEVICE_F_RANDOMNESS,
- fd, NULL, 0, handle_block_output);
-
- /* We store the device size in the private area */
- device_len = dev->priv = malloc(sizeof(*device_len));
- /* This is the safe way of establishing the size of our device: it
- * might be a normal file or an actual block device like /dev/hdb. */
- *device_len = lseek64(fd, 0, SEEK_END);
-
- /* The device memory is a "struct lguest_block_page". It's zeroed
- * already, we just need to put in the device size. Block devices
- * think in sectors (ie. 512 byte chunks), so we translate here. */
- p = dev->mem;
- p->num_sectors = *device_len/512;
- verbose("device %p: block %i sectors\n",
- (void *)(dev->desc->pfn * getpagesize()), p->num_sectors);
-}
-
-/*
- * Network Devices.
- *
- * Setting up network devices is quite a pain, because we have three types.
- * First, we have the inter-Guest network. This is a file which is mapped into
- * the address space of the Guests who are on the network. Because it is a
- * shared mapping, the same page underlies all the devices, and they can send
- * DMA to each other.
- *
- * Remember from our network driver, the Guest is told what slot in the page it
- * is to use. We use exclusive fnctl locks to reserve a slot. If another
- * Guest is using a slot, the lock will fail and we try another. Because fnctl
- * locks are cleaned up automatically when we die, this cleverly means that our
- * reservation on the slot will vanish if we crash. */
-static unsigned int find_slot(int netfd, const char *filename)
-{
- struct flock fl;
-
- fl.l_type = F_WRLCK;
- fl.l_whence = SEEK_SET;
- fl.l_len = 1;
- /* Try a 1 byte lock in each possible position number */
- for (fl.l_start = 0;
- fl.l_start < getpagesize()/sizeof(struct lguest_net);
- fl.l_start++) {
- /* If we succeed, return the slot number. */
- if (fcntl(netfd, F_SETLK, &fl) == 0)
- return fl.l_start;
- }
- errx(1, "No free slots in network file %s", filename);
-}
-
-/* This function sets up the network file */
-static void setup_net_file(const char *filename,
- struct device_list *devices)
-{
- int netfd;
- struct device *dev;
-
- /* We don't use open_or_die() here: for friendliness we create the file
- * if it doesn't already exist. */
- netfd = open(filename, O_RDWR, 0);
- if (netfd < 0) {
- if (errno == ENOENT) {
- netfd = open(filename, O_RDWR|O_CREAT, 0600);
- if (netfd >= 0) {
- /* If we succeeded, initialize the file with a
- * blank page. */
- char page[getpagesize()];
- memset(page, 0, sizeof(page));
- write(netfd, page, sizeof(page));
- }
- }
- if (netfd < 0)
- err(1, "cannot open net file '%s'", filename);
- }
-
- /* We need 1 page, and the features indicate the slot to use and that
- * no checksum is needed. We never touch this device again; it's
- * between the Guests on the network, so we don't register input or
- * output handlers. */
- dev = new_device(devices, LGUEST_DEVICE_T_NET, 1,
- find_slot(netfd, filename)|LGUEST_NET_F_NOCSUM,
- -1, NULL, 0, NULL);
-
- /* Map the shared file. */
- if (mmap(dev->mem, getpagesize(), PROT_READ|PROT_WRITE,
- MAP_FIXED|MAP_SHARED, netfd, 0) != dev->mem)
- err(1, "could not mmap '%s'", filename);
- verbose("device %p: shared net %s, peer %i\n",
- (void *)(dev->desc->pfn * getpagesize()), filename,
- dev->desc->features & ~LGUEST_NET_F_NOCSUM);
+
+ /* The console needs two virtqueues: the input then the output. We
+ * don't care when they refill the input queue, since we don't hold
+ * data waiting for them. That's why the input queue's callback is
+ * NULL. */
+ add_virtqueue(dev, VIRTQUEUE_NUM, NULL);
+ add_virtqueue(dev, VIRTQUEUE_NUM, handle_console_output);
+
+ verbose("device %u: console\n", devices.device_num++);
}
/*:*/
+
+/*M:010 Inter-guest networking is an interesting area. Simplest is to have a
+ * --sharenet=<name> option which opens or creates a named pipe. This can be
+ * used to send packets to another guest in a 1:1 manner.
+ *
+ * More sopisticated is to use one of the tools developed for project like UML
+ * to do networking.
+ *
+ * Faster is to do virtio bonding in kernel. Doing this 1:1 would be
+ * completely generic ("here's my vring, attach to your vring") and would work
+ * for any traffic. Of course, namespace and permissions issues need to be
+ * dealt with. A more sophisticated "multi-channel" virtio_net.c could hide
+ * multiple inter-guest channels behind one interface, although it would
+ * require some manner of hotplugging new virtio channels.
+ *
+ * Finally, we could implement a virtio network switch in the kernel. :*/
static u32 str2ip(const char *ipaddr)
{
@@ -1188,7 +1214,7 @@ static void add_to_bridge(int fd, const
/* This sets up the Host end of the network device with an IP address, brings
* it up so packets will flow, the copies the MAC address into the hwaddr
- * pointer (in practice, the Host's slot in the network device's memory). */
+ * pointer. */
static void configure_device(int fd, const char *devname, u32 ipaddr,
unsigned char hwaddr[6])
{
@@ -1214,18 +1240,18 @@ static void configure_device(int fd, con
memcpy(hwaddr, ifr.ifr_hwaddr.sa_data, 6);
}
-/*L:195 The other kind of network is a Host<->Guest network. This can either
- * use briding or routing, but the principle is the same: it uses the "tun"
- * device to inject packets into the Host as if they came in from a normal
- * network card. We just shunt packets between the Guest and the tun
- * device. */
-static void setup_tun_net(const char *arg, struct device_list *devices)
+/*L:195 Our network is a Host<->Guest network. This can either use bridging or
+ * routing, but the principle is the same: it uses the "tun" device to inject
+ * packets into the Host as if they came in from a normal network card. We
+ * just shunt packets between the Guest and the tun device. */
+static void setup_tun_net(const char *arg)
{
struct device *dev;
struct ifreq ifr;
int netfd, ipfd;
u32 ip;
const char *br_name = NULL;
+ u8 hwaddr[6];
/* We open the /dev/net/tun device and tell it we want a tap device. A
* tap device is like a tun device, only somehow different. To tell
@@ -1241,21 +1267,12 @@ static void setup_tun_net(const char *ar
* device: trust us! */
ioctl(netfd, TUNSETNOCSUM, 1);
- /* We create the net device with 1 page, using the features field of
- * the descriptor to tell the Guest it is in slot 1 (NET_PEERNUM), and
- * that the device has fairly random timing. We do *not* specify
- * LGUEST_NET_F_NOCSUM: these packets can reach the real world.
- *
- * We will put our MAC address is slot 0 for the Guest to see, so
- * it will send packets to us using the key "peer_offset(0)": */
- dev = new_device(devices, LGUEST_DEVICE_T_NET, 1,
- NET_PEERNUM|LGUEST_DEVICE_F_RANDOMNESS, netfd,
- handle_tun_input, peer_offset(0), handle_tun_output);
-
- /* We keep a flag which says whether we've seen packets come out from
- * this network device. */
- dev->priv = malloc(sizeof(bool));
- *(bool *)dev->priv = false;
+ /* First we create a new network device. */
+ dev = new_device("net", VIRTIO_ID_NET, netfd, handle_tun_input);
+
+ /* Network devices need a receive and a send queue. */
+ add_virtqueue(dev, VIRTQUEUE_NUM, NULL);
+ add_virtqueue(dev, VIRTQUEUE_NUM, handle_net_output);
/* We need a socket to perform the magic network ioctls to bring up the
* tap interface, connect to the bridge etc. Any socket will do! */
@@ -1271,44 +1288,251 @@ static void setup_tun_net(const char *ar
} else /* It is an IP address to set up the device with */
ip = str2ip(arg);
- /* We are peer 0, ie. first slot, so we hand dev->mem to this routine
- * to write the MAC address at the start of the device memory. */
- configure_device(ipfd, ifr.ifr_name, ip, dev->mem);
-
- /* Set "promisc" bit: we want every single packet if we're going to
- * bridge to other machines (and otherwise it doesn't matter). */
- *((u8 *)dev->mem) |= 0x1;
-
+ /* Set up the tun device, and get the mac address for the interface. */
+ configure_device(ipfd, ifr.ifr_name, ip, hwaddr);
+
+ /* Tell Guest what MAC address to use. */
+ add_desc_field(dev, VIRTIO_CONFIG_NET_MAC_F, sizeof(hwaddr), hwaddr);
+
+ /* We don't seed the socket any more; setup is done. */
close(ipfd);
- verbose("device %p: tun net %u.%u.%u.%u\n",
- (void *)(dev->desc->pfn * getpagesize()),
- (u8)(ip>>24), (u8)(ip>>16), (u8)(ip>>8), (u8)ip);
+ verbose("device %u: tun net %u.%u.%u.%u\n",
+ devices.device_num++,
+ (u8)(ip>>24),(u8)(ip>>16),(u8)(ip>>8),(u8)ip);
if (br_name)
verbose("attached to bridge: %s\n", br_name);
}
+
+
+/*
+ * Block device.
+ *
+ * Serving a block device is really easy: the Guest asks for a block number and
+ * we read or write that position in the file.
+ *
+ * Unfortunately, this is amazingly slow: the Guest waits until the read is
+ * finished before running anything else, even if it could be doing useful
+ * work. We could use async I/O, except it's reputed to suck so hard that
+ * characters actually go missing from your code when you try to use it.
+ *
+ * So we farm the I/O out to thread, and communicate with it via a pipe. */
+
+/* This hangs off device->priv, with the data. */
+struct vblk_info
+{
+ /* The size of the file. */
+ off64_t len;
+
+ /* The file descriptor for the file. */
+ int fd;
+
+ /* IO thread listens on this file descriptor [0]. */
+ int workpipe[2];
+
+ /* IO thread writes to this file descriptor to mark it done, then
+ * Launcher triggers interrupt to Guest. */
+ int done_fd;
+};
+
+/* This is the core of the I/O thread. It returns true if it did something. */
+static bool service_io(struct device *dev)
+{
+ struct vblk_info *vblk = dev->priv;
+ unsigned int head, out_num, in_num, wlen;
+ int ret;
+ struct virtio_blk_inhdr *in;
+ struct virtio_blk_outhdr *out;
+ struct iovec iov[dev->vq->vring.num];
+ off64_t off;
+
+ head = get_vq_desc(dev->vq, iov, &out_num, &in_num);
+ if (head == dev->vq->vring.num)
+ return false;
+
+ if (out_num == 0 || in_num == 0)
+ errx(1, "Bad virtblk cmd %u out=%u in=%u",
+ head, out_num, in_num);
+
+ out = convert(&iov[0], struct virtio_blk_outhdr);
+ in = convert(&iov[out_num+in_num-1], struct virtio_blk_inhdr);
+ off = out->sector * 512;
+
+ /* This is how we implement barriers. Pretty poor, no? */
+ if (out->type & VIRTIO_BLK_T_BARRIER)
+ fdatasync(vblk->fd);
+
+ if (out->type & VIRTIO_BLK_T_SCSI_CMD) {
+ fprintf(stderr, "Scsi commands unsupported\n");
+ in->status = VIRTIO_BLK_S_UNSUPP;
+ wlen = sizeof(in);
+ } else if (out->type & VIRTIO_BLK_T_OUT) {
+ /* Write */
+
+ /* Move to the right location in the block file. This can fail
+ * if they try to write past end. */
+ if (lseek64(vblk->fd, off, SEEK_SET) != off)
+ err(1, "Bad seek to sector %llu", out->sector);
+
+ ret = writev(vblk->fd, iov+1, out_num-1);
+ verbose("WRITE to sector %llu: %i\n", out->sector, ret);
+
+ /* Grr... Now we know how long the descriptor they sent was, we
+ * make sure they didn't try to write over the end of the block
+ * file (possibly extending it). */
+ if (ret > 0 && off + ret > vblk->len) {
+ /* Trim it back to the correct length */
+ ftruncate64(vblk->fd, vblk->len);
+ /* Die, bad Guest, die. */
+ errx(1, "Write past end %llu+%u", off, ret);
+ }
+ wlen = sizeof(in);
+ in->status = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
+ } else {
+ /* Read */
+
+ /* Move to the right location in the block file. This can fail
+ * if they try to read past end. */
+ if (lseek64(vblk->fd, off, SEEK_SET) != off)
+ err(1, "Bad seek to sector %llu", out->sector);
+
+ ret = readv(vblk->fd, iov+1, in_num-1);
+ verbose("READ from sector %llu: %i\n", out->sector, ret);
+ if (ret >= 0) {
+ wlen = sizeof(in) + ret;
+ in->status = VIRTIO_BLK_S_OK;
+ } else {
+ wlen = sizeof(in);
+ in->status = VIRTIO_BLK_S_IOERR;
+ }
+ }
+
+ /* We can't trigger an IRQ, because we're not the Launcher. It does
+ * that when we tell it we're done. */
+ add_used(dev->vq, head, wlen);
+ return true;
+}
+
+/* This is the thread which actually services the I/O. */
+static int io_thread(void *_dev)
+{
+ struct device *dev = _dev;
+ struct vblk_info *vblk = dev->priv;
+ char c;
+
+ /* Close other side of workpipe so we get 0 read when main dies. */
+ close(vblk->workpipe[1]);
+ /* Close the other side of the done_fd pipe. */
+ close(dev->fd);
+
+ /* When this read fails, it means Launcher died, so we follow. */
+ while (read(vblk->workpipe[0], &c, 1) == 1) {
+ /* We acknowledge each request immediately, to reduce latency,
+ * rather than waiting until we've done them all. I haven't
+ * measured to see if it makes any difference. */
+ while (service_io(dev))
+ write(vblk->done_fd, &c, 1);
+ }
+ return 0;
+}
+
+/* When the thread says some I/O is done, we interrupt the Guest. */
+static bool handle_io_finish(int fd, struct device *dev)
+{
+ char c;
+
+ /* If child died, presumably it printed message. */
+ if (read(dev->fd, &c, 1) != 1)
+ exit(1);
+
+ /* It did some work, so trigger the irq. */
+ trigger_irq(fd, dev->vq);
+ return true;
+}
+
+/* When the Guest submits some I/O, we wake the I/O thread. */
+static void handle_virtblk_output(int fd, struct virtqueue *vq)
+{
+ struct vblk_info *vblk = vq->dev->priv;
+ char c = 0;
+
+ /* Wake up I/O thread and tell it to go to work! */
+ if (write(vblk->workpipe[1], &c, 1) != 1)
+ /* Presumably it indicated why it died. */
+ exit(1);
+}
+
+/* This creates a virtual block device. */
+static void setup_block_file(const char *filename)
+{
+ int p[2];
+ struct device *dev;
+ struct vblk_info *vblk;
+ void *stack;
+ u64 cap;
+ unsigned int val;
+
+ /* This is the pipe the I/O thread will use to tell us I/O is done. */
+ pipe(p);
+
+ /* The device responds to return from I/O thread. */
+ dev = new_device("block", VIRTIO_ID_BLOCK, p[0], handle_io_finish);
+
+ /* The device has a virtqueue. */
+ add_virtqueue(dev, VIRTQUEUE_NUM, handle_virtblk_output);
+
+ /* Allocate the room for our own bookkeeping */
+ vblk = dev->priv = malloc(sizeof(*vblk));
+
+ /* First we open the file and store the length. */
+ vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE);
+ vblk->len = lseek64(vblk->fd, 0, SEEK_END);
+
+ /* Tell Guest how many sectors this device has. */
+ cap = cpu_to_le64(vblk->len / 512);
+ add_desc_field(dev, VIRTIO_CONFIG_BLK_F_CAPACITY, sizeof(cap), &cap);
+
+ /* Tell Guest not to put in too many descriptors at once: two are used
+ * for the in and out elements. */
+ val = cpu_to_le32(VIRTQUEUE_NUM - 2);
+ add_desc_field(dev, VIRTIO_CONFIG_BLK_F_SEG_MAX, sizeof(val), &val);
+
+ /* The I/O thread writes to this end of the pipe when done. */
+ vblk->done_fd = p[1];
+
+ /* This is how we tell the I/O thread about more work. */
+ pipe(vblk->workpipe);
+
+ /* Create stack for thread and run it */
+ stack = malloc(32768);
+ if (clone(io_thread, stack + 32768, CLONE_VM, dev) == -1)
+ err(1, "Creating clone");
+
+ /* We don't need to keep the I/O thread's end of the pipes open. */
+ close(vblk->done_fd);
+ close(vblk->workpipe[0]);
+
+ verbose("device %u: virtblock %llu sectors\n",
+ devices.device_num, cap);
+}
/* That's the end of device setup. */
/*L:220 Finally we reach the core of the Launcher, which runs the Guest, serves
* its input and output, and finally, lays it to rest. */
-static void __attribute__((noreturn))
-run_guest(int lguest_fd, struct device_list *device_list)
+static void __attribute__((noreturn)) run_guest(int lguest_fd)
{
for (;;) {
unsigned long args[] = { LHREQ_BREAK, 0 };
- unsigned long arr[2];
+ unsigned long notify_addr;
int readval;
/* We read from the /dev/lguest device to run the Guest. */
- readval = read(lguest_fd, arr, sizeof(arr));
-
- /* The read can only really return sizeof(arr) (the Guest did a
- * SEND_DMA to us), or an error. */
-
- /* For a successful read, arr[0] is the address of the "struct
- * lguest_dma", and arr[1] is the key the Guest sent to. */
- if (readval == sizeof(arr)) {
- handle_output(lguest_fd, arr[0], arr[1], device_list);
+ readval = read(lguest_fd, ¬ify_addr, sizeof(notify_addr));
+
+ /* One unsigned long means the Guest did HCALL_NOTIFY */
+ if (readval == sizeof(notify_addr)) {
+ verbose("Notify on address %#lx\n", notify_addr);
+ handle_output(lguest_fd, notify_addr);
continue;
/* ENOENT means the Guest died. Reading tells us why. */
} else if (errno == ENOENT) {
@@ -1322,7 +1546,7 @@ run_guest(int lguest_fd, struct device_l
/* Service input, then unset the BREAK which releases
* the Waker. */
- handle_input(lguest_fd, device_list);
+ handle_input(lguest_fd);
if (write(lguest_fd, args, sizeof(args)) < 0)
err(1, "Resetting break");
}
@@ -1336,7 +1560,6 @@ run_guest(int lguest_fd, struct device_l
static struct option opts[] = {
{ "verbose", 0, NULL, 'v' },
- { "sharenet", 1, NULL, 's' },
{ "tunnet", 1, NULL, 't' },
{ "block", 1, NULL, 'b' },
{ "initrd", 1, NULL, 'i' },
@@ -1345,7 +1568,7 @@ static void usage(void)
static void usage(void)
{
errx(1, "Usage: lguest [--verbose] "
- "[--sharenet=<filename>|--tunnet=(<ipaddr>|bridge:<bridgename>)\n"
+ "[--tunnet=(<ipaddr>|bridge:<bridgename>)\n"
"|--block=<filename>|--initrd=<filename>]...\n"
"<mem-in-mb> vmlinux [args...]");
}
@@ -1358,8 +1581,6 @@ int main(int argc, char *argv[])
unsigned long mem = 0, pgdir, start, initrd_size = 0;
/* A temporary and the /dev/lguest file descriptor. */
int i, c, lguest_fd;
- /* The list of Guest devices, based on command line arguments. */
- struct device_list device_list;
/* The boot information for the Guest. */
void *boot;
/* If they specify an initrd file to load. */
@@ -1369,11 +1590,12 @@ int main(int argc, char *argv[])
* device receive input from a file descriptor, we keep an fdset
* (infds) and the maximum fd number (max_infd) with the head of the
* list. We also keep a pointer to the last device, for easy appending
- * to the list. */
- device_list.max_infd = -1;
- device_list.dev = NULL;
- device_list.lastdev = &device_list.dev;
- FD_ZERO(&device_list.infds);
+ * to the list. Finally, we keep the next interrupt number to hand out
+ * (1: remember that 0 is used by the timer). */
+ FD_ZERO(&devices.infds);
+ devices.max_infd = -1;
+ devices.lastdev = &devices.dev;
+ devices.next_irq = 1;
/* We need to know how much memory so we can set up the device
* descriptor and memory pages for the devices as we parse the command
@@ -1390,7 +1612,7 @@ int main(int argc, char *argv[])
+ DEVICE_PAGES);
guest_limit = mem;
guest_max = mem + DEVICE_PAGES*getpagesize();
- device_list.descs = get_pages(1);
+ devices.descpage = get_pages(1);
break;
}
}
@@ -1401,14 +1623,11 @@ int main(int argc, char *argv[])
case 'v':
verbose = true;
break;
- case 's':
- setup_net_file(optarg, &device_list);
- break;
case 't':
- setup_tun_net(optarg, &device_list);
+ setup_tun_net(optarg);
break;
case 'b':
- setup_block_file(optarg, &device_list);
+ setup_block_file(optarg);
break;
case 'i':
initrd_name = optarg;
@@ -1426,7 +1645,7 @@ int main(int argc, char *argv[])
verbose("Guest base is at %p\n", guest_base);
/* We always have a console device */
- setup_console(&device_list);
+ setup_console();
/* Now we load the kernel */
start = load_kernel(open_or_die(argv[optind+1], O_RDONLY));
@@ -1468,10 +1687,10 @@ int main(int argc, char *argv[])
/* We fork off a child process, which wakes the Launcher whenever one
* of the input file descriptors needs attention. Otherwise we would
* run the Guest until it tries to output something. */
- waker_fd = setup_waker(lguest_fd, &device_list);
+ waker_fd = setup_waker(lguest_fd);
/* Finally, run the Guest. This doesn't return. */
- run_guest(lguest_fd, &device_list);
+ run_guest(lguest_fd);
}
/*:*/
--
there are those who do and those who hang on and you don't see too
many doers quoting their contemporaries. -- Larry McVoy
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