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][,ioeventfd=on][,vectors=n][,role=peer|master]
-chardev socket,path=<path>,id=<id>
The shared memory server, sample programs and init scripts are in a git repo
here:
www.gitorious.org/nahanni
Signed-off-by: Cam Macdonell <c...@cs.ualberta.ca>
---
Makefile.target | 3 +
hw/ivshmem.c | 834 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
qemu-char.c | 6 +
qemu-char.h | 3 +
qemu-doc.texi | 43 +++
5 files changed, 889 insertions(+), 0 deletions(-)
create mode 100644 hw/ivshmem.c
diff --git a/Makefile.target b/Makefile.target
index 3ef4666..4cb3a00 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -188,6 +188,9 @@ 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 += 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..3f197ae
--- /dev/null
+++ b/hw/ivshmem.c
@@ -0,0 +1,834 @@
+/*
+ * Inter-VM Shared Memory PCI device.
+ *
+ * Author:
+ * Cam Macdonell <c...@cs.ualberta.ca>
+ *
+ * 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 "hw.h"
+#include "pc.h"
+#include "pci.h"
+#include "msix.h"
+#include "kvm.h"
+
+#include <sys/mman.h>
+#include <sys/types.h>
+
+#define IVSHMEM_IOEVENTFD 0
+#define IVSHMEM_MSI 1
+
+#define IVSHMEM_PEER 0
+#define IVSHMEM_MASTER 1
+
+#define IVSHMEM_REG_BAR_SIZE 0x100
+
+//#define DEBUG_IVSHMEM
+#ifdef DEBUG_IVSHMEM
+#define IVSHMEM_DPRINTF(fmt, ...) \
+ do {printf("IVSHMEM: " fmt, ## __VA_ARGS__); } while (0)
+#else
+#define IVSHMEM_DPRINTF(fmt, ...)
+#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;
+ 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;
+ int role_val; /* scalar to avoid multiple string comparisons */
+} 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,
+ unsigned int feature) {
+ return (ivs->features & (1 << feature));
+}
+
+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);
+ }
+
+ IVSHMEM_DPRINTF("guest pci addr = %" FMT_PCIBUS ", guest h/w addr = %"
+ PRIu64 ", size = %" FMT_PCIBUS "\n", addr, s->ivshmem_offset, size);
+
+}
+
+/* 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, target_phys_addr_t addr,
+ uint32_t val)
+{
+
+ IVSHMEM_DPRINTF("We shouldn't be writing words\n");
+}
+
+static void ivshmem_io_writel(void *opaque, target_phys_addr_t addr,
+ uint32_t val)
+{
+ IVShmemState *s = opaque;
+
+ uint64_t write_one = 1;
+ uint16_t dest = val >> 16;
+ uint16_t vector = val & 0xff;
+
+ addr &= 0xfc;
+
+ IVSHMEM_DPRINTF("writing to addr " TARGET_FMT_plx "\n", addr);
+ 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 %" PRId64 " to VM %d on vector %d\n",
+ write_one, dest, vector);
+ 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, target_phys_addr_t addr,
+ uint32_t val)
+{
+ IVSHMEM_DPRINTF("We shouldn't be writing bytes\n");
+}
+
+static uint32_t ivshmem_io_readw(void *opaque, target_phys_addr_t addr)
+{
+
+ IVSHMEM_DPRINTF("We shouldn't be reading words\n");
+ return 0;
+}
+
+static uint32_t ivshmem_io_readl(void *opaque, target_phys_addr_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 " TARGET_FMT_plx "\n", addr);
+ ret = 0;
+ }
+
+ return ret;
+}
+
+static uint32_t ivshmem_io_readb(void *opaque, target_phys_addr_t addr)
+{
+ IVSHMEM_DPRINTF("We shouldn't be reading bytes\n");
+
+ return 0;
+}
+
+static CPUReadMemoryFunc * const ivshmem_mmio_read[3] = {
+ ivshmem_io_readb,
+ ivshmem_io_readw,
+ ivshmem_io_readl,
+};
+
+static CPUWriteMemoryFunc * const ivshmem_mmio_write[3] = {
+ ivshmem_io_writeb,
+ ivshmem_io_writew,
+ ivshmem_io_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("interrupt 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) {
+ fprintf(stderr, "creating eventfd for eventfd %d failed\n", eventfd);
+ 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 (%" PRIu64 " > %ld)\n",
+ s->ivshmem_size, buf.st_size);
+ 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_alloc_from_ptr(&s->dev.qdev, "ivshmem.bar2",
+ s->ivshmem_size, ptr);
+
+ /* 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++) {
+ kvm_set_ioeventfd_mmio_long(s->peers[posn].eventfds[i],
+ s->mmio_addr + DOORBELL, (posn << 16) | i, 0);
+ close(s->peers[posn].eventfds[i]);
+ }
+
+ 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);
+ }
+ }
+}
+
+/* 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));
+
+ /* 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_max_eventfd;
+ 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_alloc_from_ptr(&s->dev.qdev,
+ "ivshmem.bar2", s->ivshmem_size, map_ptr);
+
+ IVSHMEM_DPRINTF("guest pci addr = %" FMT_PCIBUS ", guest h/w addr = %"
+ PRIu64 ", size = %" PRIu64 "\n", s->shm_pci_addr,
+ s->ivshmem_offset, 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);
+ }
+
+ /* 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_max_eventfd = s->peers[incoming_posn].nb_eventfds;
+
+ if (guest_max_eventfd == 0) {
+ /* one eventfd per MSI vector */
+ s->peers[incoming_posn].eventfds = (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_max_eventfd, incoming_fd);
+ s->peers[incoming_posn].eventfds[guest_max_eventfd] = 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) {
+ if (!ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
+ /* initialize char device for callback
+ * if this is one of my eventfds */
+ s->eventfd_chr[guest_max_eventfd] = create_eventfd_chr_device(s,
+ s->peers[s->vm_id].eventfds[guest_max_eventfd],
+ guest_max_eventfd);
+ }
+ }
+
+ if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
+ kvm_set_ioeventfd_mmio_long(incoming_fd, s->mmio_addr + DOORBELL,
+ (incoming_posn << 16) | guest_max_eventfd, 1);
+ }
+
+ return;
+}
+
+static void ivshmem_reset(DeviceState *d)
+{
+ IVShmemState *s = DO_UPCAST(IVShmemState, dev.qdev, d);
+
+ s->intrstatus = 0;
+ 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, IVSHMEM_REG_BAR_SIZE,
+ s->ivshmem_mmio_io_addr);
+
+ if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
+ setup_ioeventfds(s);
+ }
+}
+
+static uint64_t ivshmem_get_size(IVShmemState * s) {
+
+ uint64_t value;
+ char *ptr;
+
+ value = strtoull(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 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");
+ exit(1);
+ }
+
+ /* '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_IOEVENTFD)) {
+ /* 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);
+ }
+
+}
+
+static int ivshmem_load(QEMUFile* f, void *opaque, int version_id)
+{
+ IVSHMEM_DPRINTF("ivshmem_load\n");
+
+ IVShmemState *proxy = opaque;
+ int ret, i;
+
+ if (version_id > 0) {
+ return -EINVAL;
+ }
+
+ if (proxy->role_val == IVSHMEM_PEER) {
+ fprintf(stderr, "ivshmem: 'peer' devices are not migratable\n");
+ return -EINVAL;
+ }
+
+ 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(&s->dev.qdev, "ivshmem", 0, 0, ivshmem_save, ivshmem_load,
+ dev);
+
+ /* IRQFD requires MSI */
+ if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD) &&
+ !ivshmem_has_feature(s, IVSHMEM_MSI)) {
+ fprintf(stderr, "ivshmem: ioeventfd/irqfd requires MSI\n");
+ exit(1);
+ }
+
+ /* check that role is reasonable */
+ if (s->role) {
+ if (strncmp(s->role, "peer", 5) == 0) {
+ s->role_val = IVSHMEM_PEER;
+ } else if (strncmp(s->role, "master", 7) == 0) {
+ s->role_val = IVSHMEM_MASTER;
+ } else {
+ fprintf(stderr, "ivshmem: 'role' must be 'peer' or 'master'\n");
+ exit(1);
+ }
+ } else {
+ s->role_val = IVSHMEM_MASTER; /* default */
+ }
+
+ if (s->role_val == IVSHMEM_PEER) {
+ register_device_unmigratable(&s->dev.qdev, "ivshmem", s);
+ }
+
+ pci_conf = s->dev.config;
+ pci_config_set_vendor_id(pci_conf, PCI_VENDOR_ID_REDHAT_QUMRANET);
+ pci_conf[0x02] = 0x10;
+ pci_conf[0x03] = 0x11;
+ pci_conf[PCI_COMMAND] = PCI_COMMAND_IO | PCI_COMMAND_MEMORY;
+ pci_config_set_class(pci_conf, PCI_CLASS_MEMORY_RAM);
+ pci_conf[PCI_HEADER_TYPE] = PCI_HEADER_TYPE_NORMAL;
+
+ pci_config_set_interrupt_pin(pci_conf, 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, IVSHMEM_REG_BAR_SIZE,
+ 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 */
+
+ if (s->shmobj != NULL) {
+ fprintf(stderr, "WARNING: do not specify both 'chardev' "
+ "and 'shm' with ivshmem\n");
+ }
+
+ 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 = qemu_mallocz(s->vectors * sizeof(CharDriverState *));
+
+ 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");
+ }
+
+ 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, "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, "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);
+ unregister_savevm(&dev->qdev, "ivshmem", s);
+
+ 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),
+ DEFINE_PROP_UINT32("vectors", IVShmemState, vectors, 1),
+ DEFINE_PROP_BIT("ioeventfd", IVShmemState, features,
IVSHMEM_IOEVENTFD, 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 9b69d92..6a3952c 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2087,6 +2087,12 @@ 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);
+
extern int term_escape_char;
/* async I/O support */
diff --git a/qemu-doc.texi b/qemu-doc.texi
index e67bf44..55a966f 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][,ioeventfd=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 guest will not be able to migrate with the device
attached.
+With the @option{peer} case, the device should be detached and then reattached
+after migration using the PCI hotplug support.
+
@node direct_linux_boot
@section Direct Linux Boot
--
1.6.3.2.198.g6096d
