On Mon, Jun 7, 2010 at 4:41 PM, Cam Macdonell <cam@xxxxxxxxxxxxxx> wrote:
> On Sat, Jun 5, 2010 at 3:44 AM, Blue Swirl <blauwirbel@xxxxxxxxx> wrote:
>> On Fri, Jun 4, 2010 at 9:45 PM, Cam Macdonell <cam@xxxxxxxxxxxxxx> wrote:
>>> 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][,role=peer|master]
>>> -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 | 852 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>> qemu-char.c | 6 +
>>> qemu-char.h | 3 +
>>> qemu-doc.texi | 43 +++
>>> 5 files changed, 907 insertions(+), 0 deletions(-)
>>> create mode 100644 hw/ivshmem.c
>>>
>>> diff --git a/Makefile.target b/Makefile.target
>>> index c4ba592..4888308 100644
>>> --- a/Makefile.target
>>> +++ b/Makefile.target
>>> @@ -202,6 +202,9 @@ obj-$(CONFIG_USB_OHCI) += usb-ohci.o
>>> obj-y += rtl8139.o
>>> obj-y += e1000.o
>>>
>>> +# Inter-VM PCI shared memory
>>> +obj-y += ivshmem.o
>>> +
>>
>> Can this be compiled once, simply by moving this to Makefile.objs
>> instead of Makefile.target? Also, because the code seems to be KVM
>> specific, it can't be compiled unconditionally but depending on at
>> least CONFIG_KVM and maybe CONFIG_EVENTFD.
>
> The device uses eventfds for signalling, but never creates the
> eventfds itself as they are passed from a server using SCM_RIGHTS.
> So, it does not depend on the eventfd API. Its dependence on
> irqfd/ioeventfd (the only KVM specific bits) are optional via the
> command-line.
>
> A runtime check for KVM is done for the reasons Avi mentioned.
>
>>
>> Why is this KVM specific BTW, Posix SHM is available on many
>> platforms? What would happen if kvm_set_foobar functions were not
>> called when KVM is not being used? Is host eventfd support essential?
>>
>>> # Hardware support
>>> obj-i386-y += vga.o
>>> obj-i386-y += mc146818rtc.o i8259.o pc.o
>>> diff --git a/hw/ivshmem.c b/hw/ivshmem.c
>>> new file mode 100644
>>> index 0000000..9057612
>>> --- /dev/null
>>> +++ b/hw/ivshmem.c
>>> @@ -0,0 +1,852 @@
>>> +/*
>>> + * Inter-VM Shared Memory PCI device.
>>> + *
>>> + * Author:
>>> + * Cam Macdonell <cam@xxxxxxxxxxxxxx>
>>> + *
>>> + * Based On: cirrus_vga.c
>>> + * Copyright (c) 2004 Fabrice Bellard
>>> + * Copyright (c) 2004 Makoto Suzuki (suzu)
>>> + *
>>> + * and rtl8139.c
>>> + * Copyright (c) 2006 Igor Kovalenko
>>> + *
>>> + * 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 "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)
>>
>> Please use __VA_ARGS__.
>>
>>> +#else
>>> +#define IVSHMEM_DPRINTF(fmt, args...)
>>> +#endif
>>> +
>>> +typedef struct Peer {
>>> + int nb_eventfds;
>>> + int *eventfds;
>>> +} Peer;
>>> +
>>> +typedef struct EventfdEntry {
>>> + PCIDevice *pdev;
>>> + int vector;
>>> +} EventfdEntry;
>>> +
>>> +typedef struct IVShmemState {
>>> + PCIDevice dev;
>>> + uint32_t intrmask;
>>> + uint32_t intrstatus;
>>> + uint32_t doorbell;
>>> +
>>> + CharDriverState ** eventfd_chr;
>>
>> I'd remove the space between '**' and 'eventfd_chr', it's used inconsistently.
>>
>>> + CharDriverState * server_chr;
>>> + int ivshmem_mmio_io_addr;
>>> +
>>> + pcibus_t mmio_addr;
>>> + pcibus_t shm_pci_addr;
>>> + uint64_t ivshmem_offset;
>>> + uint64_t ivshmem_size; /* size of shared memory region */
>>> + int shm_fd; /* shared memory file descriptor */
>>> +
>>> + Peer *peers;
>>> + int nb_peers; /* how many guests we have space for */
>>> + int max_peer; /* maximum numbered peer */
>>> +
>>> + int vm_id;
>>> + uint32_t vectors;
>>> + uint32_t features;
>>> + EventfdEntry *eventfd_table;
>>> +
>>> + char * shmobj;
>>> + char * sizearg;
>>> + char * role;
>>> +} IVShmemState;
>>> +
>>> +/* registers for the Inter-VM shared memory device */
>>> +enum ivshmem_registers {
>>> + IntrMask = 0,
>>> + IntrStatus = 4,
>>> + IVPosition = 8,
>>> + Doorbell = 12,
>>> +};
>>
>> IIRC these should be uppercase.
>
> I worked from rtl8139 which doesn't have them uppercase. But doing a
> quick search, I can see most devices do, I'll fix that.
>
>>
>>> +
>>> +static inline uint32_t ivshmem_has_feature(IVShmemState *ivs, int feature) {
>>> + return (ivs->features & (1 << feature));
>>> +}
>>
>> Since this is the first version, do we need any features at this
>> point, can't we expect that all features are available now? Why does
>> the user need to specify the features?
>
> Some features require host support such as irqfd/ioeventfds. So
> having features allows them to be disabled on the command-line (e.g.,
> irqfd=off).
>
>>
>> To avoid a negative shift, I'd make 'feature' unsigned.
>>
>>> +
>>> +static inline bool is_power_of_two(uint64_t 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);
>>> +
>>> + s->shm_pci_addr = addr;
>>> +
>>> + if (s->ivshmem_offset > 0) {
>>> + cpu_register_physical_memory(s->shm_pci_addr, s->ivshmem_size,
>>> + s->ivshmem_offset);
>>> + if (s->role && strncmp(s->role, "peer", 4) == 0) {
>>> + IVSHMEM_DPRINTF("marking pages no migrate\n");
>>> + cpu_mark_pages_no_migrate(s->ivshmem_offset, s->ivshmem_size);
>>> + }
>>> + }
>>> +
>>> + IVSHMEM_DPRINTF("guest pci addr = %u, guest h/w addr = %u, size = %u\n",
>>> + (uint32_t)addr, (uint32_t)s->ivshmem_offset, (uint32_t)size);
>>
>> Please use FMT_PCIBUS for addr and size and PRIu64 for 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;
>>
>> Please use uintNN_t instead of u_intNN_t.
>>
>>> + u_int16_t dest = val >> 16;
>>> + u_int16_t vector = val & 0xff;
>>> +
>>> + addr &= 0xfc;
>>
>> I'd add a debug printf here, likewise for exit of ivshmem_io_readl().
>> When you do the merge (see below), the correct printf format for the
>> addresses will be TARGET_FMT_plx.
>>
>>> +
>>> + switch (addr)
>>> + {
>>> + case IntrMask:
>>> + ivshmem_IntrMask_write(s, val);
>>> + break;
>>> +
>>> + case IntrStatus:
>>> + ivshmem_IntrStatus_write(s, val);
>>> + break;
>>> +
>>> + case Doorbell:
>>> + /* check that dest VM ID is reasonable */
>>> + if ((dest < 0) || (dest > s->max_peer)) {
>>> + IVSHMEM_DPRINTF("Invalid destination VM ID (%d)\n", dest);
>>> + break;
>>> + }
>>> +
>>> + /* check doorbell range */
>>> + if ((vector >= 0) && (vector < s->peers[dest].nb_eventfds)) {
>>> + IVSHMEM_DPRINTF("Writing %ld to VM %d on vector %d\n",
>>> + write_one, dest, vector);
>>
>> PRId64 for write_one, %ld is not enough on ILP32.
>>
>>> + if (write(s->peers[dest].eventfds[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 VM ID if the memory is mapped */
>>> + if (s->shm_fd > 0) {
>>> + ret = s->vm_id;
>>> + } else {
>>> + ret = -1;
>>> + }
>>> + 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);
>>> +}
>>
>> This function and others below only performs a cast and useless
>> masking (the address passed is these days an offset from start of the
>> area). Please merge these to ivshmem_io_readl() etc.
>
> Ok, these are artifacts from basing my patch on rtl8139.c. I'll remove them.
>
>>
>>> +
>>> +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] = {
>>
>> Please add 'const'.
>>
>>> + 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 %p %d\n", pdev, 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);
>>
>> This should not be a DPRINTF.
>>
>>> + exit(-1);
>>> + }
>>> +
>>> + /* if MSI is supported we need multiple interrupts */
>>> + 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 fd) {
>>> + /* check that the guest isn't going to try and map more memory than the
>>> + * the object has allocated return -1 to indicate error */
>>> +
>>> + struct stat buf;
>>> +
>>> + fstat(fd, &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);
>>
>> Please use PRIx64 for s->ivshmem_size, this will cause a warning on ILP32.
>>
>>> + return -1;
>>> + } else {
>>> + return 0;
>>> + }
>>> +}
>>> +
>>> +/* create the shared memory BAR when we are not using the server, so we can
>>> + * create the BAR and map the memory immediately */
>>> +static void create_shared_memory_BAR(IVShmemState *s, int fd) {
>>> +
>>> + void * ptr;
>>> +
>>> + s->shm_fd = fd;
>>> +
>>> + ptr = mmap(0, s->ivshmem_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
>>> +
>>> + s->ivshmem_offset = qemu_ram_map(s->ivshmem_size, ptr);
>>
>> qemu_ram_map() does not exist in HEAD.
>>
>
> Ok, so qemu_ram_map() and kvm_set_irq() are in the KVM HEAD. I had my
> own version of both functions, but removed them when Marcelo's were
> merged into KVM.
>
>>> +
>>> + /* 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->peers[posn].nb_eventfds;
>>> +
>>> + for (i = 0; i < guest_curr_max; i++)
>>> + close(s->peers[posn].eventfds[i]);
>>
>> CODING_STYLE.
>>
>>> +
>>> + qemu_free(s->peers[posn].eventfds);
>>> + s->peers[posn].nb_eventfds = 0;
>>> +}
>>> +
>>> +static void setup_ioeventfds(IVShmemState *s) {
>>> +
>>> + int i, j;
>>> +
>>> + for (i = 0; i <= s->max_peer; i++) {
>>> + for (j = 0; j < s->peers[i].nb_eventfds; j++) {
>>> + kvm_set_ioeventfd_mmio_long(s->peers[i].eventfds[j],
>>> + s->mmio_addr + Doorbell, (i << 16) | j, 1);
>>> + }
>>> + }
>>> +
>>> + /* setup irqfd for this VM's eventfds */
>>> + for (i = 0; i < s->vectors; i++) {
>>> + kvm_set_irqfd(s->dev.msix_irq_entries[i].gsi,
>>> + s->peers[s->vm_id].eventfds[i], 1);
>>
>> kvm_set_irqfd() does not exist in HEAD.
>>
>>> + }
>>> +}
>>> +
>>> +
>>> +/* 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_nb_alloc;
>>> +
>>> + old_nb_alloc = s->nb_peers;
>>> +
>>> + while (new_min_size >= s->nb_peers)
>>> + s->nb_peers = s->nb_peers * 2;
>>> +
>>> + IVSHMEM_DPRINTF("bumping storage to %d guests\n", s->nb_peers);
>>> + s->peers = qemu_realloc(s->peers, s->nb_peers * sizeof(Peer));
>>> +
>>> + if (s->peers == NULL) {
>>> + fprintf(stderr, "Allocation error - exiting\n");
>>> + exit(1);
>>> + }
>>
>> qemu_realloc will never return zero.
>>
>>> +
>>> + /* zero out new pointers */
>>> + for (j = old_nb_alloc; j < s->nb_peers; j++) {
>>> + s->peers[j].eventfds = NULL;
>>> + s->peers[j].nb_eventfds = 0;
>>> + }
>>> +}
>>> +
>>> +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->server_chr->msgfd and store it, posn should accompany msg */
>>> + tmp_fd = qemu_chr_get_msgfd(s->server_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->nb_peers) {
>>> + 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->peers[incoming_posn].eventfds == 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 (incoming_fd == -1) {
>>> + fprintf(stderr, "could not allocate file descriptor %s\n",
>>> + strerror(errno));
>>> + return;
>>> + }
>>> +
>>> + /* if the position is -1, then it's shared memory region fd */
>>> + if (incoming_posn == -1) {
>>> +
>>> + void * map_ptr;
>>> +
>>> + s->max_peer = 0;
>>> +
>>> + if (check_shm_size(s, incoming_fd) == -1) {
>>> + exit(-1);
>>> + }
>>> +
>>> + /* mmap the region and map into the BAR2 */
>>> + map_ptr = mmap(0, s->ivshmem_size, PROT_READ|PROT_WRITE, MAP_SHARED,
>>> + incoming_fd, 0);
>>> + s->ivshmem_offset = qemu_ram_map(s->ivshmem_size, map_ptr);
>>> +
>>> + IVSHMEM_DPRINTF("guest pci addr = %u, guest h/w addr = %u, size = %u\n",
>>> + (uint32_t)s->shm_pci_addr, (uint32_t)s->ivshmem_offset,
>>> + (uint32_t)s->ivshmem_size);
>>> +
>>> + if (s->shm_pci_addr > 0) {
>>> + /* map memory into BAR2 */
>>> + cpu_register_physical_memory(s->shm_pci_addr, s->ivshmem_size,
>>> + s->ivshmem_offset);
>>> + if (s->role && strncmp(s->role, "peer", 4) == 0) {
>>> + IVSHMEM_DPRINTF("marking pages no migrate\n");
>>> + cpu_mark_pages_no_migrate(s->ivshmem_offset, s->ivshmem_size);
>>> + }
>>> +
>>> + }
>>> +
>>> + /* only store the fd if it is successfully mapped */
>>> + s->shm_fd = 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->peers[incoming_posn].nb_eventfds;
>>> + if (guest_curr_max == 0) {
>>> + /* one eventfd per MSI vector */
>>> + s->peers[incoming_posn].eventfds = (int *) qemu_malloc(s->vectors *
>>> + sizeof(int));
>>
>> Useless cast in C.
>>
>>> + }
>>> +
>>> + /* this is an eventfd for a particular guest VM */
>>> + IVSHMEM_DPRINTF("eventfds[%ld][%d] = %d\n", incoming_posn, guest_curr_max,
>>> + incoming_fd);
>>> + s->peers[incoming_posn].eventfds[guest_curr_max] = incoming_fd;
>>> +
>>> + /* increment count for particular guest */
>>> + s->peers[incoming_posn].nb_eventfds++;
>>> +
>>> + /* keep track of the maximum VM ID */
>>> + if (incoming_posn > s->max_peer) {
>>> + s->max_peer = incoming_posn;
>>> + }
>>> +
>>> + if (incoming_posn == s->vm_id) {
>>> + int vector = guest_curr_max;
>>
>> Why add a new variable?
>
> for clarity, so when looking at the code it's clear that the current
> maxium is a MSI vector. Perhaps I'll rename guest_curr_max to achieve
> this.
>
>>
>>> + if (!ivshmem_has_feature(s, IVSHMEM_IRQFD)) {
>>> + /* initialize char device for callback
>>> + * if this is one of my eventfds */
>>> + s->eventfd_chr[vector] = create_eventfd_chr_device(s,
>>> + s->peers[s->vm_id].eventfds[vector], vector);
>>> + }
>>> + }
>>> +
>>> + return;
>>> +}
>>> +
>>> +static void ivshmem_reset(DeviceState *d)
>>> +{
>>> + return;
>>
>> Nothing to do?
>
> Oversight, will fix.
>
>>
>>> +}
>>> +
>>> +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);
>>
>> The 0x400 should be #defined earlier. Why 0x400 since you are only
>> interested in the 0x100 first bytes?
>
> We bumped to 1MB for a previous version that had multiple doorbells.
> ioeventfd masks eliminated made multiple doorbells unnecessary. I'll
> put it back to 0x100.
>
>>
>>> +
>>> + /* ioeventfd and irqfd are enabled together,
>>> + * so the flag IRQFD refers to both */
>>> + if (ivshmem_has_feature(s, IVSHMEM_IRQFD)) {
>>> + setup_ioeventfds(s);
>>> + }
>>> +}
>>> +
>>> +static uint64_t ivshmem_get_size(IVShmemState * s) {
>>> +
>>> + uint64_t value;
>>> + char *ptr;
>>> +
>>> + value = strtoul(s->sizearg, &ptr, 10);
>>
>> I'd use strtoull() but the whole function should be suppressed, see below.
>>
>>> + 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);
>>> + }
>>
>> Isn't the BAR check in pci.c enough?
>
> This would produce a clearer error that it is the ivshmem device that
> is the problem.
>
>>
>>> +
>>> + return value;
>>> +
>>> +}
>>> +
>>> +static void ivshmem_setup_msi(IVShmemState * s) {
>>> +
>>> + int i;
>>> +
>>> + /* allocate the MSI-X vectors */
>>> +
>>> + 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");
>>
>> Is this fatal considering the msix_vector_use() below?
>
> Perhaps not, we could fall back to regular interrupts. Could move the
> msix_vector_use() into the "then" clause.
>
>>
>>> + }
>>> +
>>> + /* 'activate' the vectors */
>>> + for (i = 0; i < s->vectors; i++) {
>>> + msix_vector_use(&s->dev, i);
>>> + }
>>> +
>>> + /* if IRQFDs are not supported, we'll have to trigger the interrupts
>>> + * via Qemu char devices */
>>> + if (!ivshmem_has_feature(s, IVSHMEM_IRQFD)) {
>>> + /* for handling interrupts when IRQFD is not available */
>>> + s->eventfd_table = qemu_mallocz(s->vectors * sizeof(EventfdEntry));
>>> + }
>>> +}
>>> +
>>> +static void ivshmem_save(QEMUFile* f, void *opaque)
>>> +{
>>> + IVShmemState *proxy = opaque;
>>> +
>>> + IVSHMEM_DPRINTF("ivshmem_save\n");
>>> + pci_device_save(&proxy->dev, f);
>>> +
>>> + if (ivshmem_has_feature(proxy, IVSHMEM_MSI)) {
>>> + msix_save(&proxy->dev, f);
>>> + } else {
>>> + qemu_put_be32(f, proxy->intrstatus);
>>> + qemu_put_be32(f, proxy->intrmask);
>>> + }
>>> +
>>> +}
>>
>> There may be VMState magic to handle conditional structures (or just
>> make the structures unconditional), so VMState should be used instead.
>
> MSI-X requires the use of the old-style savevm/loadvm functions.
> Should VMState and the load/save be used together?
They do the same thing. Maybe MSI-X should be fixed then.
>>
>>> +
>>> +static int ivshmem_load(QEMUFile* f, void *opaque, int version_id)
>>> +{
>>> + IVSHMEM_DPRINTF("ivshmem_load\n");
>>> +
>>> + IVShmemState *proxy = opaque;
>>> + int ret, i;
>>> +
>>
>> Missing version check.
>>
>>> + ret = pci_device_load(&proxy->dev, f);
>>> + if (ret) {
>>> + return ret;
>>> + }
>>> +
>>> + if (ivshmem_has_feature(proxy, IVSHMEM_MSI)) {
>>> + msix_load(&proxy->dev, f);
>>> + for (i = 0; i < proxy->vectors; i++) {
>>> + msix_vector_use(&proxy->dev, i);
>>> + }
>>> + } else {
>>> + proxy->intrstatus = qemu_get_be32(f);
>>> + proxy->intrmask = qemu_get_be32(f);
>>> + }
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int pci_ivshmem_init(PCIDevice *dev)
>>> +{
>>> + IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
>>> + uint8_t *pci_conf;
>>> +
>>> + if (s->sizearg == NULL)
>>> + s->ivshmem_size = 4 << 20; /* 4 MB default */
>>> + else {
>>> + s->ivshmem_size = ivshmem_get_size(s);
>>> + }
>>> +
>>> + register_savevm("ivshmem", 0, 0, ivshmem_save, ivshmem_load, dev);
>>> +
>>> + /* 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);
>>> + }
>>> +
>>> + /* check that role is reasonable */
>>> + if (s->role && !((strncmp(s->role, "peer", 5) == 0) ||
>>> + (strncmp(s->role, "master", 7) == 0))) {
>>> + fprintf(stderr, "ivshmem: 'role' must be 'peer' or 'master'\n");
>>> + exit(1);
>>> + }
>>
>> I'd add a scalar flag in IVShmemState for role so that further strcmps
>> are avoided.
>>
>>> +
>>> + 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;
>>
>> Please add the DID to hw/pci_ids.h and use pci_config_set_xyz() here.
>>
>>> + 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 */
>>> +
>>> + pci_conf[PCI_INTERRUPT_PIN] = 1;
>>> +
>>> + s->shm_pci_addr = 0;
>>> + s->ivshmem_offset = 0;
>>> + s->shm_fd = 0;
>>> +
>>> + 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);
>>> +
>>> + if ((s->server_chr != NULL) &&
>>> + (strncmp(s->server_chr->filename, "unix:", 5) == 0)) {
>>> + /* if we get a UNIX socket as the parameter we will talk
>>> + * to the ivshmem server to receive the memory region */
>>> +
>>> + IVSHMEM_DPRINTF("using shared memory server (socket = %s)\n",
>>> + s->server_chr->filename);
>>> +
>>> + if (ivshmem_has_feature(s, IVSHMEM_MSI)) {
>>> + ivshmem_setup_msi(s);
>>> + }
>>> +
>>> + /* we allocate enough space for 16 guests and grow as needed */
>>> + s->nb_peers = 16;
>>> + s->vm_id = -1;
>>> +
>>> + /* allocate/initialize space for interrupt handling */
>>> + s->peers = qemu_mallocz(s->nb_peers * sizeof(Peer));
>>> +
>>> + pci_register_bar(&s->dev, 2, s->ivshmem_size,
>>> + PCI_BASE_ADDRESS_SPACE_MEMORY, ivshmem_map);
>>> +
>>> + s->eventfd_chr = (CharDriverState **) qemu_mallocz(s->vectors *
>>> + sizeof(CharDriverState *));
>>
>> Useless cast in C.
>>
>>> +
>>> + qemu_chr_add_handlers(s->server_chr, ivshmem_can_receive, ivshmem_read,
>>> + ivshmem_event, s);
>>> + } 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");
>>> + }
>>
>> I'd rather have separate 'chardev' and 'shm_file' parameters. Then
>> 'info qtree' could return more useful information about the chardev.
>
> can you elaborate? the command-line currently must be one of the following
>
> server case:
> -ivshmem chardev=x,...
> -chardev id=x,...
>
> or
>
> non-server case:
> -ivshmem shm=<name>,...
Never mind, I was confused.
>
>>
>>> +
>>> + 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");
>>
>> Why 'kvm_ivshmem'?
>
> old name, will remove.
>
>>
>>> + }
>>> +
>>> + } 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);
>>> +
>>> + }
>>> +
>>> + if (check_shm_size(s, fd) == -1) {
>>> + 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, server_chr),
>>> + DEFINE_PROP_STRING("size", IVShmemState, sizearg),
>>
>> This should be scalar type, not string.
>
> but it needs to handle the 'm' and 'g' suffixes for memory sizes.
>
>>
>>> + 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_STRING("role", IVShmemState, role),
>>> + 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 ac65a1c..b2e50d0 100644
>>> --- a/qemu-char.c
>>> +++ b/qemu-char.c
>>> @@ -2093,6 +2093,12 @@ 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 e3a0783..6ea01ba 100644
>>> --- a/qemu-char.h
>>> +++ b/qemu-char.h
>>> @@ -94,6 +94,9 @@ 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);
>>
>> Maybe this should be removed and just open coded with qemu_chr_open_fd.
>
> I'm indifferent, it just looked a little funny passing the parameter twice.
>
>>
>>> +
>>> extern int term_escape_char;
>>>
>>> /* async I/O support */
>>> diff --git a/qemu-doc.texi b/qemu-doc.texi
>>> index 6647b7b..24f8748 100644
>>> --- a/qemu-doc.texi
>>> +++ b/qemu-doc.texi
>>> @@ -706,6 +706,49 @@ 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>[,chardev=<id>]
>>> + [,msi=on][,irqfd=on][,vectors=n][,role=peer|master]
>>> +qemu -chardev socket,path=<path>,id=<id>
>>> +@end example
>>> +
>>> +When using the server, the guest will be assigned a VM ID (>=0) that allows guests
>>> +using the same server to communicate via interrupts. Guests can read their
>>> +VM ID from a device register (see example code). Since receiving the shared
>>> +memory region from the server is asynchronous, there is a (small) chance the
>>> +guest may boot before the shared memory is attached. To allow an application
>>> +to ensure shared memory is attached, the VM ID register will return -1 (an
>>> +invalid VM ID) until the memory is attached. Once the shared memory is
>>> +attached, the VM ID will return the guest's valid VM ID. With these semantics,
>>> +the guest application can check to ensure the shared memory is attached to the
>>> +guest before proceeding.
>>> +
>>> +The @option{role} argument can be set to either master or peer and will affect
>>> +how the shared memory is migrated. With @option{role=master}, the guest will
>>> +copy the shared memory on migration to the destination host. With
>>> +@option{role=peer}, the shared memory will not be copied on migration. Only
>>> +one guest should be specified as
>>> +the master.
>>> +
>>> @node direct_linux_boot
>>> @section Direct Linux Boot
>>>
>>> --
>>> 1.6.3.2.198.g6096d
>>>
>>>
>>>
>>
>>
>
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