Support an inter-vm shared memory device that maps a shared-memory object as a
PCI device in the guest. This patch also supports interrupts between guest by
communicating over a unix domain socket. This patch applies to the qemu-kvm
repository.
-device ivshmem,size=<size in format accepted by -m>[,shm=<shm name>]
Interrupts are supported between multiple VMs by using a shared memory server
by using a chardev socket.
-device ivshmem,size=<size in format accepted by -m>[,shm=<shm name>]
[,chardev=<id>][,msi=on][,irqfd=on][,vectors=n]
-chardev socket,path=<path>,id=<id>
(shared memory server is qemu.git/contrib/ivshmem-server)
Sample programs and init scripts are in a git repo here:
www.gitorious.org/nahanni
---
Makefile.target | 3 +
hw/ivshmem.c | 727 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
qemu-char.c | 6 +
qemu-char.h | 3 +
qemu-doc.texi | 25 ++
5 files changed, 764 insertions(+), 0 deletions(-)
create mode 100644 hw/ivshmem.c
diff --git a/Makefile.target b/Makefile.target
index 1ffd802..bc9a681 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -199,6 +199,9 @@ obj-$(CONFIG_USB_OHCI) += usb-ohci.o
obj-y += rtl8139.o
obj-y += e1000.o
+# Inter-VM PCI shared memory
+obj-y += ivshmem.o
+
# Hardware support
obj-i386-y = pckbd.o dma.o
obj-i386-y += vga.o
diff --git a/hw/ivshmem.c b/hw/ivshmem.c
new file mode 100644
index 0000000..f8d8fdb
--- /dev/null
+++ b/hw/ivshmem.c
@@ -0,0 +1,727 @@
+/*
+ * Inter-VM Shared Memory PCI device.
+ *
+ * Author:
+ * Cam Macdonell <cam@xxxxxxxxxxxxxx>
+ *
+ * Based On: cirrus_vga.c and rtl8139.c
+ *
+ * This code is licensed under the GNU GPL v2.
+ */
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/io.h>
+#include <sys/ioctl.h>
+#include <sys/eventfd.h>
+#include "hw.h"
+#include "console.h"
+#include "pc.h"
+#include "pci.h"
+#include "sysemu.h"
+
+#include "msix.h"
+#include "qemu-kvm.h"
+#include "libkvm.h"
+
+#include <sys/eventfd.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+
+#define IVSHMEM_IRQFD 0
+#define IVSHMEM_MSI 1
+
+#define DEBUG_IVSHMEM
+#ifdef DEBUG_IVSHMEM
+#define IVSHMEM_DPRINTF(fmt, args...) \
+ do {printf("IVSHMEM: " fmt, ##args); } while (0)
+#else
+#define IVSHMEM_DPRINTF(fmt, args...)
+#endif
+
+typedef struct EventfdEntry {
+ PCIDevice *pdev;
+ int vector;
+} EventfdEntry;
+
+typedef struct IVShmemState {
+ PCIDevice dev;
+ uint32_t intrmask;
+ uint32_t intrstatus;
+ uint32_t doorbell;
+
+ CharDriverState * chr;
+ CharDriverState ** eventfd_chr;
+ int ivshmem_mmio_io_addr;
+
+ pcibus_t mmio_addr;
+ unsigned long ivshmem_offset;
+ uint64_t ivshmem_size; /* size of shared memory region */
+ int shm_fd; /* shared memory file descriptor */
+
+ int nr_allocated_vms;
+ /* array of eventfds for each guest */
+ int ** eventfds;
+ /* keep track of # of eventfds for each guest*/
+ int * eventfds_posn_count;
+
+ int nr_alloc_guests;
+ int vm_id;
+ int num_eventfds;
+ uint32_t vectors;
+ uint32_t features;
+ EventfdEntry *eventfd_table;
+
+ char * shmobj;
+ char * sizearg;
+} IVShmemState;
+
+/* registers for the Inter-VM shared memory device */
+enum ivshmem_registers {
+ IntrMask = 0,
+ IntrStatus = 4,
+ IVPosition = 8,
+ Doorbell = 12,
+};
+
+static inline uint32_t ivshmem_has_feature(IVShmemState *ivs, int feature) {
+ return (ivs->features & (1 << feature));
+}
+
+static inline int is_power_of_two(int x) {
+ return (x & (x-1)) == 0;
+}
+
+static void ivshmem_map(PCIDevice *pci_dev, int region_num,
+ pcibus_t addr, pcibus_t size, int type)
+{
+ IVShmemState *s = DO_UPCAST(IVShmemState, dev, pci_dev);
+
+ IVSHMEM_DPRINTF("addr = %u size = %u\n", (uint32_t)addr, (uint32_t)size);
+ cpu_register_physical_memory(addr, s->ivshmem_size, s->ivshmem_offset);
+
+}
+
+/* accessing registers - based on rtl8139 */
+static void ivshmem_update_irq(IVShmemState *s, int val)
+{
+ int isr;
+ isr = (s->intrstatus & s->intrmask) & 0xffffffff;
+
+ /* don't print ISR resets */
+ if (isr) {
+ IVSHMEM_DPRINTF("Set IRQ to %d (%04x %04x)\n",
+ isr ? 1 : 0, s->intrstatus, s->intrmask);
+ }
+
+ qemu_set_irq(s->dev.irq[0], (isr != 0));
+}
+
+static void ivshmem_IntrMask_write(IVShmemState *s, uint32_t val)
+{
+ IVSHMEM_DPRINTF("IntrMask write(w) val = 0x%04x\n", val);
+
+ s->intrmask = val;
+
+ ivshmem_update_irq(s, val);
+}
+
+static uint32_t ivshmem_IntrMask_read(IVShmemState *s)
+{
+ uint32_t ret = s->intrmask;
+
+ IVSHMEM_DPRINTF("intrmask read(w) val = 0x%04x\n", ret);
+
+ return ret;
+}
+
+static void ivshmem_IntrStatus_write(IVShmemState *s, uint32_t val)
+{
+ IVSHMEM_DPRINTF("IntrStatus write(w) val = 0x%04x\n", val);
+
+ s->intrstatus = val;
+
+ ivshmem_update_irq(s, val);
+ return;
+}
+
+static uint32_t ivshmem_IntrStatus_read(IVShmemState *s)
+{
+ uint32_t ret = s->intrstatus;
+
+ /* reading ISR clears all interrupts */
+ s->intrstatus = 0;
+
+ ivshmem_update_irq(s, 0);
+
+ return ret;
+}
+
+static void ivshmem_io_writew(void *opaque, uint8_t addr, uint32_t val)
+{
+
+ IVSHMEM_DPRINTF("We shouldn't be writing words\n");
+}
+
+static void ivshmem_io_writel(void *opaque, uint8_t addr, uint32_t val)
+{
+ IVShmemState *s = opaque;
+
+ u_int64_t write_one = 1;
+ u_int16_t dest = val >> 16;
+ u_int16_t vector = val & 0xff;
+
+ addr &= 0xfe;
+
+ switch (addr)
+ {
+ case IntrMask:
+ ivshmem_IntrMask_write(s, val);
+ break;
+
+ case IntrStatus:
+ ivshmem_IntrStatus_write(s, val);
+ break;
+
+ case Doorbell:
+ /* check doorbell range */
+ if ((vector >= 0) && (vector < s->eventfds_posn_count[dest])) {
+ IVSHMEM_DPRINTF("Writing %ld to VM %d on vector %d\n", write_one, dest, vector);
+ if (write(s->eventfds[dest][vector], &(write_one), 8) != 8) {
+ IVSHMEM_DPRINTF("error writing to eventfd\n");
+ }
+ }
+ break;
+ default:
+ IVSHMEM_DPRINTF("Invalid VM Doorbell VM %d\n", dest);
+ }
+}
+
+static void ivshmem_io_writeb(void *opaque, uint8_t addr, uint32_t val)
+{
+ IVSHMEM_DPRINTF("We shouldn't be writing bytes\n");
+}
+
+static uint32_t ivshmem_io_readw(void *opaque, uint8_t addr)
+{
+
+ IVSHMEM_DPRINTF("We shouldn't be reading words\n");
+ return 0;
+}
+
+static uint32_t ivshmem_io_readl(void *opaque, uint8_t addr)
+{
+
+ IVShmemState *s = opaque;
+ uint32_t ret;
+
+ switch (addr)
+ {
+ case IntrMask:
+ ret = ivshmem_IntrMask_read(s);
+ break;
+
+ case IntrStatus:
+ ret = ivshmem_IntrStatus_read(s);
+ break;
+
+ case IVPosition:
+ /* return my id in the ivshmem list */
+ ret = s->vm_id;
+ break;
+
+ default:
+ IVSHMEM_DPRINTF("why are we reading 0x%x\n", addr);
+ ret = 0;
+ }
+
+ return ret;
+
+}
+
+static uint32_t ivshmem_io_readb(void *opaque, uint8_t addr)
+{
+ IVSHMEM_DPRINTF("We shouldn't be reading bytes\n");
+
+ return 0;
+}
+
+static void ivshmem_mmio_writeb(void *opaque,
+ target_phys_addr_t addr, uint32_t val)
+{
+ ivshmem_io_writeb(opaque, addr & 0xFF, val);
+}
+
+static void ivshmem_mmio_writew(void *opaque,
+ target_phys_addr_t addr, uint32_t val)
+{
+ ivshmem_io_writew(opaque, addr & 0xFF, val);
+}
+
+static void ivshmem_mmio_writel(void *opaque,
+ target_phys_addr_t addr, uint32_t val)
+{
+ ivshmem_io_writel(opaque, addr & 0xFF, val);
+}
+
+static uint32_t ivshmem_mmio_readb(void *opaque, target_phys_addr_t addr)
+{
+ return ivshmem_io_readb(opaque, addr & 0xFF);
+}
+
+static uint32_t ivshmem_mmio_readw(void *opaque, target_phys_addr_t addr)
+{
+ uint32_t val = ivshmem_io_readw(opaque, addr & 0xFF);
+ return val;
+}
+
+static uint32_t ivshmem_mmio_readl(void *opaque, target_phys_addr_t addr)
+{
+ uint32_t val = ivshmem_io_readl(opaque, addr & 0xFF);
+ return val;
+}
+
+static CPUReadMemoryFunc *ivshmem_mmio_read[3] = {
+ ivshmem_mmio_readb,
+ ivshmem_mmio_readw,
+ ivshmem_mmio_readl,
+};
+
+static CPUWriteMemoryFunc *ivshmem_mmio_write[3] = {
+ ivshmem_mmio_writeb,
+ ivshmem_mmio_writew,
+ ivshmem_mmio_writel,
+};
+
+static void ivshmem_receive(void *opaque, const uint8_t *buf, int size)
+{
+ IVShmemState *s = opaque;
+
+ ivshmem_IntrStatus_write(s, *buf);
+
+ IVSHMEM_DPRINTF("ivshmem_receive 0x%02x\n", *buf);
+}
+
+static int ivshmem_can_receive(void * opaque)
+{
+ return 8;
+}
+
+static void ivshmem_event(void *opaque, int event)
+{
+ IVSHMEM_DPRINTF("ivshmem_event %d\n", event);
+}
+
+static void fake_irqfd(void *opaque, const uint8_t *buf, int size) {
+
+ EventfdEntry *entry = opaque;
+ PCIDevice *pdev = entry->pdev;
+
+ IVSHMEM_DPRINTF("fake irqfd on vector %d\n", entry->vector);
+ msix_notify(pdev, entry->vector);
+}
+
+static CharDriverState* create_eventfd_chr_device(void * opaque, int eventfd,
+ int vector)
+{
+ /* create a event character device based on the passed eventfd */
+ IVShmemState *s = opaque;
+ CharDriverState * chr;
+
+ chr = qemu_chr_open_eventfd(eventfd);
+
+ if (chr == NULL) {
+ IVSHMEM_DPRINTF("creating eventfd for eventfd %d failed\n", eventfd);
+ exit(-1);
+ }
+
+ if (ivshmem_has_feature(s, IVSHMEM_MSI)) {
+ s->eventfd_table[vector].pdev = &s->dev;
+ s->eventfd_table[vector].vector = vector;
+
+ qemu_chr_add_handlers(chr, ivshmem_can_receive, fake_irqfd,
+ ivshmem_event, &s->eventfd_table[vector]);
+ } else {
+ qemu_chr_add_handlers(chr, ivshmem_can_receive, ivshmem_receive,
+ ivshmem_event, s);
+ }
+
+ return chr;
+
+}
+
+static int check_shm_size(IVShmemState *s, int shmemfd) {
+ /* check that the guest isn't going to try and map more memory than the
+ * card server allocated return -1 to indicate error */
+
+ struct stat buf;
+
+ fstat(shmemfd, &buf);
+
+ if (s->ivshmem_size > buf.st_size) {
+ fprintf(stderr, "IVSHMEM ERROR: Requested memory size greater");
+ fprintf(stderr, " than shared object size (%ld > %ld)\n",
+ s->ivshmem_size, buf.st_size);
+ return -1;
+ } else {
+ return 0;
+ }
+}
+
+static void create_shared_memory_BAR(IVShmemState *s, int fd) {
+
+ s->shm_fd = fd;
+
+ s->ivshmem_offset = qemu_ram_mmap(s->shm_fd, s->ivshmem_size,
+ MAP_SHARED, 0);
+
+ /* region for shared memory */
+ pci_register_bar(&s->dev, 2, s->ivshmem_size,
+ PCI_BASE_ADDRESS_SPACE_MEMORY, ivshmem_map);
+}
+
+static void close_guest_eventfds(IVShmemState *s, int posn)
+{
+ int i, guest_curr_max;
+
+ guest_curr_max = s->eventfds_posn_count[posn];
+
+ for (i = 0; i < guest_curr_max; i++)
+ close(s->eventfds[posn][i]);
+
+ free(s->eventfds[posn]);
+ s->eventfds_posn_count[posn] = 0;
+}
+
+/* this function increase the dynamic storage need to store data about other
+ * guests */
+static void increase_dynamic_storage(IVShmemState *s, int new_min_size) {
+
+ int j, old_nr_alloc;
+
+ old_nr_alloc = s->nr_alloc_guests;
+
+ while (s->nr_alloc_guests < new_min_size)
+ s->nr_alloc_guests = s->nr_alloc_guests * 2;
+
+ IVSHMEM_DPRINTF("bumping storage to %d guests\n", s->nr_alloc_guests);
+ s->eventfds = qemu_realloc(s->eventfds, s->nr_alloc_guests *
+ sizeof(int *));
+ s->eventfds_posn_count = qemu_realloc(s->eventfds_posn_count,
+ s->nr_alloc_guests *
+ sizeof(int));
+ s->eventfd_table = qemu_realloc(s->eventfd_table, s->nr_alloc_guests *
+ sizeof(EventfdEntry));
+
+ if ((s->eventfds == NULL) || (s->eventfds_posn_count == NULL) ||
+ (s->eventfd_table == NULL)) {
+ fprintf(stderr, "Allocation error - exiting\n");
+ exit(1);
+ }
+
+ if (!ivshmem_has_feature(s, IVSHMEM_IRQFD)) {
+ s->eventfd_chr = (CharDriverState **)qemu_realloc(s->eventfd_chr,
+ s->nr_alloc_guests * sizeof(void *));
+ if (s->eventfd_chr == NULL) {
+ fprintf(stderr, "Allocation error - exiting\n");
+ exit(1);
+ }
+ }
+
+ /* zero out new pointers */
+ for (j = old_nr_alloc; j < s->nr_alloc_guests; j++) {
+ s->eventfds[j] = NULL;
+ }
+}
+
+static void ivshmem_read(void *opaque, const uint8_t * buf, int flags)
+{
+ IVShmemState *s = opaque;
+ int incoming_fd, tmp_fd;
+ int guest_curr_max;
+ long incoming_posn;
+
+ memcpy(&incoming_posn, buf, sizeof(long));
+ /* pick off s->chr->msgfd and store it, posn should accompany msg */
+ tmp_fd = qemu_chr_get_msgfd(s->chr);
+ IVSHMEM_DPRINTF("posn is %ld, fd is %d\n", incoming_posn, tmp_fd);
+
+ /* make sure we have enough space for this guest */
+ if (incoming_posn >= s->nr_alloc_guests) {
+ increase_dynamic_storage(s, incoming_posn);
+ }
+
+ if (tmp_fd == -1) {
+ /* if posn is positive and unseen before then this is our posn*/
+ if ((incoming_posn >= 0) && (s->eventfds[incoming_posn] == NULL)) {
+ /* receive our posn */
+ s->vm_id = incoming_posn;
+ return;
+ } else {
+ /* otherwise an fd == -1 means an existing guest has gone away */
+ IVSHMEM_DPRINTF("posn %ld has gone away\n", incoming_posn);
+ close_guest_eventfds(s, incoming_posn);
+ return;
+ }
+ }
+
+ /* because of the implementation of get_msgfd, we need a dup */
+ incoming_fd = dup(tmp_fd);
+
+ /* if the position is -1, then it's shared memory region fd */
+ if (incoming_posn == -1) {
+
+ s->num_eventfds = 0;
+
+ if (check_shm_size(s, incoming_fd) == -1) {
+ exit(-1);
+ }
+
+ /* creating a BAR in qemu_chr callback may be crazy */
+ create_shared_memory_BAR(s, incoming_fd);
+
+ return;
+ }
+
+ /* each guest has an array of eventfds, and we keep track of how many
+ * guests for each VM */
+ guest_curr_max = s->eventfds_posn_count[incoming_posn];
+ if (guest_curr_max == 0) {
+ /* one eventfd per MSI vector */
+ s->eventfds[incoming_posn] = (int *) qemu_malloc(s->vectors *
+ sizeof(int));
+ }
+
+ /* this is an eventfd for a particular guest VM */
+ IVSHMEM_DPRINTF("eventfds[%ld][%d] = %d\n", incoming_posn, guest_curr_max,
+ incoming_fd);
+ s->eventfds[incoming_posn][guest_curr_max] = incoming_fd;
+
+ /* increment count for particular guest */
+ s->eventfds_posn_count[incoming_posn]++;
+
+ /* ioeventfd and irqfd are enabled together,
+ * so the flag IRQFD refers to both */
+ if (ivshmem_has_feature(s, IVSHMEM_IRQFD) && guest_curr_max >= 0) {
+ /* allocate ioeventfd for the new fd
+ * received for guest @ incoming_posn */
+ kvm_set_ioeventfd_mmio_long(incoming_fd, s->mmio_addr + Doorbell,
+ (incoming_posn << 16) | guest_curr_max, 1);
+ }
+
+ /* keep track of the maximum VM ID */
+ if (incoming_posn > s->num_eventfds) {
+ s->num_eventfds = incoming_posn;
+ }
+
+ if (incoming_posn == s->vm_id) {
+ if (ivshmem_has_feature(s, IVSHMEM_IRQFD)) {
+ /* setup irqfd for this VM's eventfd */
+ int vector = guest_curr_max;
+ kvm_set_irqfd(s->eventfds[s->vm_id][guest_curr_max], vector,
+ s->dev.msix_irq_entries[vector].gsi);
+ } else {
+ /* initialize char device for callback
+ * if this is one of my eventfd */
+ s->eventfd_chr[guest_curr_max] = create_eventfd_chr_device(s,
+ s->eventfds[s->vm_id][guest_curr_max], guest_curr_max);
+ }
+ }
+
+ return;
+}
+
+static void ivshmem_reset(DeviceState *d)
+{
+ return;
+}
+
+static void ivshmem_mmio_map(PCIDevice *pci_dev, int region_num,
+ pcibus_t addr, pcibus_t size, int type)
+{
+ IVShmemState *s = DO_UPCAST(IVShmemState, dev, pci_dev);
+
+ s->mmio_addr = addr;
+ cpu_register_physical_memory(addr + 0, 0x400, s->ivshmem_mmio_io_addr);
+
+ /* now that our mmio region has been allocated, we can receive
+ * the file descriptors */
+ if (s->chr != NULL) {
+ qemu_chr_add_handlers(s->chr, ivshmem_can_receive, ivshmem_read,
+ ivshmem_event, s);
+ }
+
+}
+
+static uint64_t ivshmem_get_size(IVShmemState * s) {
+
+ uint64_t value;
+ char *ptr;
+
+ value = strtoul(s->sizearg, &ptr, 10);
+ switch (*ptr) {
+ case 0: case 'M': case 'm':
+ value <<= 20;
+ break;
+ case 'G': case 'g':
+ value <<= 30;
+ break;
+ default:
+ fprintf(stderr, "qemu: invalid ram size: %s\n", s->sizearg);
+ exit(1);
+ }
+
+ /* BARs must be a power of 2 */
+ if (!is_power_of_two(value)) {
+ fprintf(stderr, "ivshmem: size must be power of 2\n");
+ exit(1);
+ }
+
+ return value;
+
+}
+
+static int pci_ivshmem_init(PCIDevice *dev)
+{
+ IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
+ uint8_t *pci_conf;
+ int i;
+
+ if (s->sizearg == NULL)
+ s->ivshmem_size = 4 << 20; /* 4 MB default */
+ else {
+ s->ivshmem_size = ivshmem_get_size(s);
+ }
+
+ /* IRQFD requires MSI */
+ if (ivshmem_has_feature(s, IVSHMEM_IRQFD) &&
+ !ivshmem_has_feature(s, IVSHMEM_MSI)) {
+ fprintf(stderr, "ivshmem: ioeventfd/irqfd requires MSI\n");
+ exit(1);
+ }
+
+ pci_conf = s->dev.config;
+ pci_conf[0x00] = 0xf4; /* Qumranet vendor ID 0x5002 */
+ pci_conf[0x01] = 0x1a;
+ pci_conf[0x02] = 0x10;
+ pci_conf[0x03] = 0x11;
+ pci_conf[0x04] = PCI_COMMAND_IO | PCI_COMMAND_MEMORY;
+ pci_conf[0x0a] = 0x00; /* RAM controller */
+ pci_conf[0x0b] = 0x05;
+ pci_conf[0x0e] = 0x00; /* header_type */
+
+ s->ivshmem_mmio_io_addr = cpu_register_io_memory(ivshmem_mmio_read,
+ ivshmem_mmio_write, s);
+ /* region for registers*/
+ pci_register_bar(&s->dev, 0, 0x400,
+ PCI_BASE_ADDRESS_SPACE_MEMORY, ivshmem_mmio_map);
+
+ /* allocate the MSI-X vectors */
+ if (ivshmem_has_feature(s, IVSHMEM_MSI)) {
+
+ if (!msix_init(&s->dev, s->vectors, 1, 0)) {
+ pci_register_bar(&s->dev, 1,
+ msix_bar_size(&s->dev),
+ PCI_BASE_ADDRESS_SPACE_MEMORY,
+ msix_mmio_map);
+ IVSHMEM_DPRINTF("msix initialized (%d vectors)\n", s->vectors);
+ } else {
+ IVSHMEM_DPRINTF("msix initialization failed\n");
+ }
+
+ /* 'activate' the vectors */
+ for (i = 0; i < s->vectors; i++) {
+ msix_vector_use(&s->dev, i);
+ }
+ }
+
+ if ((s->chr != NULL) && (strncmp(s->chr->filename, "unix:", 5) == 0)) {
+ /* if we get a UNIX socket as the parameter we will talk
+ * to the ivshmem server later once the MMIO BAR is actually
+ * allocated (see ivshmem_mmio_map) */
+
+ IVSHMEM_DPRINTF("using shared memory server (socket = %s)\n",
+ s->chr->filename);
+
+ /* we allocate enough space for 16 guests and grow as needed */
+ s->nr_alloc_guests = 16;
+ s->vm_id = -1;
+
+ /* allocate/initialize space for interrupt handling */
+ s->eventfds = qemu_mallocz(s->nr_alloc_guests * sizeof(int *));
+ s->eventfd_table = qemu_mallocz(s->vectors * sizeof(EventfdEntry));
+ s->eventfds_posn_count = qemu_mallocz(s->nr_alloc_guests * sizeof(int));
+
+ pci_conf[PCI_INTERRUPT_PIN] = 1; /* we are going to support interrupts */
+
+ if (!ivshmem_has_feature(s, IVSHMEM_IRQFD)) {
+ s->eventfd_chr = (CharDriverState **)qemu_malloc(s->nr_alloc_guests *
+ sizeof(void *));
+ }
+
+ } else {
+ /* just map the file immediately, we're not using a server */
+ int fd;
+
+ if (s->shmobj == NULL) {
+ fprintf(stderr, "Must specify 'chardev' or 'shm' to ivshmem\n");
+ }
+
+ IVSHMEM_DPRINTF("using shm_open (shm object = %s)\n", s->shmobj);
+
+ /* try opening with O_EXCL and if it succeeds zero the memory
+ * by truncating to 0 */
+ if ((fd = shm_open(s->shmobj, O_CREAT|O_RDWR|O_EXCL,
+ S_IRWXU|S_IRWXG|S_IRWXO)) > 0) {
+ /* truncate file to length PCI device's memory */
+ if (ftruncate(fd, s->ivshmem_size) != 0) {
+ fprintf(stderr, "kvm_ivshmem: could not truncate shared file\n");
+ }
+
+ } else if ((fd = shm_open(s->shmobj, O_CREAT|O_RDWR,
+ S_IRWXU|S_IRWXG|S_IRWXO)) < 0) {
+ fprintf(stderr, "kvm_ivshmem: could not open shared file\n");
+ exit(-1);
+ }
+
+ create_shared_memory_BAR(s, fd);
+
+ }
+
+
+ return 0;
+}
+
+static int pci_ivshmem_uninit(PCIDevice *dev)
+{
+ IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
+
+ cpu_unregister_io_memory(s->ivshmem_mmio_io_addr);
+
+ return 0;
+}
+
+static PCIDeviceInfo ivshmem_info = {
+ .qdev.name = "ivshmem",
+ .qdev.size = sizeof(IVShmemState),
+ .qdev.reset = ivshmem_reset,
+ .init = pci_ivshmem_init,
+ .exit = pci_ivshmem_uninit,
+ .qdev.props = (Property[]) {
+ DEFINE_PROP_CHR("chardev", IVShmemState, chr),
+ DEFINE_PROP_STRING("size", IVShmemState, sizearg),
+ DEFINE_PROP_UINT32("vectors", IVShmemState, vectors, 1),
+ DEFINE_PROP_BIT("irqfd", IVShmemState, features, IVSHMEM_IRQFD, false),
+ DEFINE_PROP_BIT("msi", IVShmemState, features, IVSHMEM_MSI, true),
+ DEFINE_PROP_STRING("shm", IVShmemState, shmobj),
+ DEFINE_PROP_END_OF_LIST(),
+ }
+};
+
+static void ivshmem_register_devices(void)
+{
+ pci_qdev_register(&ivshmem_info);
+}
+
+device_init(ivshmem_register_devices)
diff --git a/qemu-char.c b/qemu-char.c
index 048da3f..41cb8c7 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2076,6 +2076,12 @@ static void tcp_chr_read(void *opaque)
}
}
+CharDriverState *qemu_chr_open_eventfd(int eventfd){
+
+ return qemu_chr_open_fd(eventfd, eventfd);
+
+}
+
static void tcp_chr_connect(void *opaque)
{
CharDriverState *chr = opaque;
diff --git a/qemu-char.h b/qemu-char.h
index 3a9427b..1571091 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -93,6 +93,9 @@ void qemu_chr_info_print(Monitor *mon, const QObject *ret_data);
void qemu_chr_info(Monitor *mon, QObject **ret_data);
CharDriverState *qemu_chr_find(const char *name);
+/* add an eventfd to the qemu devices that are polled */
+CharDriverState *qemu_chr_open_eventfd(int eventfd);
+
extern int term_escape_char;
/* async I/O support */
diff --git a/qemu-doc.texi b/qemu-doc.texi
index 6647b7b..2df4687 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -706,6 +706,31 @@ Using the @option{-net socket} option, it is possible to make VLANs
that span several QEMU instances. See @ref{sec_invocation} to have a
basic example.
+@section Other Devices
+
+@subsection Inter-VM Shared Memory device
+
+With KVM enabled on a Linux host, a shared memory device is available. Guests
+map a POSIX shared memory region into the guest as a PCI device that enables
+zero-copy communication to the application level of the guests. The basic
+syntax is:
+
+@example
+qemu -device ivshmem,size=<size in format accepted by -m>[,shm=<shm name>]
+@end example
+
+If desired, interrupts can be sent between guest VMs accessing the same shared
+memory region. Interrupt support requires using a shared memory server and
+using a chardev socket to connect to it. The code for the shared memory server
+is qemu.git/contrib/ivshmem-server. An example syntax when using the shared
+memory server is:
+
+@example
+qemu -device ivshmem,size=<size in format accepted by -m>[,shm=<shm name>]
+ [,chardev=<id>][,msi=on][,irqfd=on][,vectors=n]
+qemu -chardev socket,path=<path>,id=<id>
+@end example
+
@node direct_linux_boot
@section Direct Linux Boot
--
1.6.2.5
--
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