diff mbox

Support an inter-vm shared memory device that maps a shared-memory object

Message ID 1267467562-23539-1-git-send-email-cam@cs.ualberta.ca (mailing list archive)
State New, archived
Headers show

Commit Message

Cam Macdonell March 1, 2010, 6:19 p.m. UTC
None
diff mbox

Patch

diff --git a/Makefile.target b/Makefile.target
index 40ff6d5..3df9006 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -216,6 +216,9 @@  obj-y += pcnet.o
 obj-y += rtl8139.o
 obj-y += e1000.o
 
+# Inter-VM PCI shared memory
+obj-y += ivshmem.o
+
 # Hardware support
 obj-i386-y = ide/core.o ide/qdev.o ide/isa.o ide/pci.o ide/piix.o
 obj-i386-y += pckbd.o $(sound-obj-y) dma.o
diff --git a/hw/ivshmem.c b/hw/ivshmem.c
new file mode 100644
index 0000000..6bf6e0a
--- /dev/null
+++ b/hw/ivshmem.c
@@ -0,0 +1,678 @@ 
+/*
+ * Inter-VM Shared Memory PCI device.
+ *
+ * Author:
+ *      Cam Macdonell <cam@cs.ualberta.ca>
+ *
+ * Based On: cirrus_vga.c and rtl8139.c
+ *
+ * This code is licensed under the GNU GPL v2.
+ */
+
+#include "hw.h"
+#include "console.h"
+#include "pc.h"
+#include "pci.h"
+#include "sysemu.h"
+
+#include "qemu-common.h"
+#include <sys/mman.h>
+#include <sys/socket.h>
+
+#define PCI_COMMAND_IOACCESS                0x0001
+#define PCI_COMMAND_MEMACCESS               0x0002
+#define PCI_COMMAND_BUSMASTER               0x0004
+
+#define DEBUG_IVSHMEM
+#define MAX_EVENT_FDS 16
+
+#ifdef DEBUG_IVSHMEM
+#define IVSHMEM_DPRINTF(fmt, args...)        \
+    do {printf("IVSHMEM: " fmt, ##args); } while (0)
+#else
+#define IVSHMEM_DPRINTF(fmt, args...)
+#endif
+
+#define BROADCAST_VAL ((1 << 8) - 1)
+
+typedef struct IVShmemState {
+    uint16_t intrmask;
+    uint16_t intrstatus;
+    uint16_t doorbell;
+    uint8_t *ivshmem_ptr;
+    unsigned long ivshmem_offset;
+    unsigned int ivshmem_size;
+    unsigned long bios_offset;
+    unsigned int bios_size;
+    target_phys_addr_t base_ctrl;
+    int it_shift;
+    PCIDevice *pci_dev;
+    CharDriverState * chr;
+    CharDriverState * eventfd_chr;
+    unsigned long map_addr;
+    unsigned long map_end;
+    int ivshmem_mmio_io_addr;
+    int eventfds[16]; /* for now we have a limit of 16 inter-connected guests */
+    int eventfd_posn;
+    int shm_fd; /* shared memory file descriptor */
+    uint16_t eventfd_bitvec;
+    int num_eventfds;
+} IVShmemState;
+
+typedef struct PCI_IVShmemState {
+    PCIDevice dev;
+    IVShmemState ivshmem_state;
+} PCI_IVShmemState;
+
+typedef struct IVShmemDesc {
+    char name[1024];
+    char * chrdev;
+    int size;
+} IVShmemDesc;
+
+/* registers for the Inter-VM shared memory device */
+enum ivshmem_registers {
+    IntrMask = 0,
+    IntrStatus = 16,
+    Doorbell = 32,
+    IVPosition = 48,
+    IVLiveList = 64,
+    MemSize = 80
+};
+
+static int num_ivshmem_devices = 0;
+static IVShmemDesc ivshmem_desc;
+
+static void ivshmem_map(PCIDevice *pci_dev, int region_num,
+                    pcibus_t addr, pcibus_t size, int type)
+{
+    PCI_IVShmemState *d = (PCI_IVShmemState *)pci_dev;
+    IVShmemState *s = &d->ivshmem_state;
+
+    IVSHMEM_DPRINTF("addr = %u size = %u\n", (uint32_t)addr, (uint32_t)size);
+    cpu_register_physical_memory(addr, s->ivshmem_size, s->ivshmem_offset);
+
+}
+
+void ivshmem_init(const char * optarg) {
+
+    char * temp;
+    char * ivshmem_sz;
+    int size;
+
+    num_ivshmem_devices++;
+
+    /* currently we only support 1 device */
+    if (num_ivshmem_devices > MAX_IVSHMEM_DEVICES) {
+        return;
+    }
+
+    temp = strdup(optarg);
+/*
+    snprintf(ivshmem_desc.name, 1024, "/%s", strsep(&temp,","));
+*/
+    ivshmem_sz=strsep(&temp,",");
+
+    if (ivshmem_sz != NULL) {
+        size = atol(ivshmem_sz);
+    } else {
+        size = -1;
+    }
+
+    ivshmem_desc.chrdev = strsep(&temp,"\0");
+
+    if ( size == -1) {
+        ivshmem_desc.size = TARGET_PAGE_SIZE;
+    } else {
+        ivshmem_desc.size = size*1024*1024;
+    }
+    IVSHMEM_DPRINTF("optarg is %s, name is %s, size is %d, chrdev is %s\n",
+                                        optarg, ivshmem_desc.name,
+                                        ivshmem_desc.size, ivshmem_desc.chrdev);
+}
+
+int ivshmem_get_size(void) {
+    return ivshmem_desc.size;
+}
+
+static void broadcast_eventfds(int val, IVShmemState *s)
+{
+
+    int dest = val >> 4;
+    u_int64_t writelong = val & 0xff;
+
+    for (dest = 1; dest < s->num_eventfds; dest++) {
+
+        if (s->eventfds[dest] != -1) {
+            IVSHMEM_DPRINTF("Writing %ld to VM %d\n", writelong, dest);
+            if (write(s->eventfds[dest], &(writelong), 8) != 8)
+                IVSHMEM_DPRINTF("error writing to eventfd\n");
+        }
+
+    }
+
+}
+
+/* accessing registers - based on rtl8139 */
+static void ivshmem_update_irq(IVShmemState *s)
+{
+    int isr;
+    isr = (s->intrstatus & s->intrmask) & 0xffff;
+
+    /* 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->pci_dev->irq[0], (isr != 0));
+}
+
+static void ivshmem_mmio_map(PCIDevice *pci_dev, int region_num,
+                       pcibus_t addr, pcibus_t size, int type)
+{
+    PCI_IVShmemState *d = (PCI_IVShmemState *)pci_dev;
+    IVShmemState *s = &d->ivshmem_state;
+
+    cpu_register_physical_memory(addr + 0, 0x100, s->ivshmem_mmio_io_addr);
+}
+
+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);
+}
+
+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);
+    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);
+
+    return ret;
+}
+
+static void ivshmem_io_writew(void *opaque, uint8_t addr, uint32_t val)
+{
+    IVShmemState *s = opaque;
+
+    // 32-bits are written to the address
+    int dest = val >> 8;
+    u_int64_t writelong = val & 0xff;
+
+    IVSHMEM_DPRINTF("writing 0x%x to 0x%lx\n", addr, (unsigned long) opaque);
+
+    addr &= 0xfe;
+
+    switch (addr)
+    {
+        case IntrMask:
+            ivshmem_IntrMask_write(s, val);
+            break;
+
+        case IntrStatus:
+            ivshmem_IntrStatus_write(s, val);
+            break;
+
+        case Doorbell:
+            IVSHMEM_DPRINTF("val is %d\n", val);
+
+            if (dest == BROADCAST_VAL) {
+                broadcast_eventfds(val, s);
+            } else if (dest <= s->num_eventfds) {
+                IVSHMEM_DPRINTF("Writing %ld to VM %d\n", writelong, dest);
+                if (write(s->eventfds[dest], &(writelong), 8) != 8)
+                    IVSHMEM_DPRINTF("error writing to eventfd\n");
+            } else {
+                IVSHMEM_DPRINTF("Invalid %ld to VM %d\n", writelong, dest);
+            }
+
+            break;
+       default:
+            IVSHMEM_DPRINTF("why are we writing 0x%x\n", addr);
+    }
+}
+
+static void ivshmem_io_writel(void *opaque, uint8_t addr, uint32_t val)
+{
+    IVSHMEM_DPRINTF("We shouldn't be writing longs\n");
+}
+
+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)
+{
+
+    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->eventfd_posn;
+            break;
+        case IVLiveList:
+            /* return the list of live VMs id for ivshmem */
+            ret = s->eventfd_bitvec;
+            break;
+
+        default:
+            IVSHMEM_DPRINTF("why are we reading 0x%x\n", addr);
+            ret = 0;
+    }
+
+    return ret;
+}
+
+static uint32_t ivshmem_io_readl(void *opaque, uint8_t addr)
+{
+    IVSHMEM_DPRINTF("We shouldn't be reading longs\n");
+    return 0;
+}
+
+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 void ivshmem_event(void *opaque, int event)
+{
+//    IVShmemState *s = opaque;
+    IVSHMEM_DPRINTF("ivshmem_event %d\n", event);
+}
+
+static int ivshmem_can_receive(void * opaque)
+{
+    return 8;
+}
+
+static CharDriverState* create_eventfd_chr_device(void * opaque, int eventfd)
+{
+    // 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);
+    }
+
+    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 (%d > %ld)\n",
+                                          s->ivshmem_size, buf.st_size);
+        return -1;
+    } else {
+        return 0;
+    }
+}
+
+static void ivshmem_read(void *opaque, const uint8_t * buf, int flags)
+{
+    IVShmemState *s = opaque;
+    int incoming_fd, tmp_fd;
+    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);
+
+    if (tmp_fd == -1) {
+        s->eventfd_posn = 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 fd */
+    if (incoming_posn == -1) {
+        s->shm_fd = incoming_fd;
+
+        s->eventfd_bitvec = 0;
+        s->num_eventfds = 0;
+
+        if (check_shm_size(s, s->shm_fd) == -1) {
+            exit(-1);
+        }
+
+        if (mmap(s->ivshmem_ptr, ivshmem_desc.size, PROT_READ|PROT_WRITE,
+                    MAP_SHARED|MAP_FIXED, s->shm_fd, 0) == MAP_FAILED)
+        {
+            fprintf(stderr, "kvm_ivshmem: could not mmap shared file\n");
+            exit(-1);
+        }
+
+        return;
+    }
+
+    /* this is an eventfd for a particular guest VM */
+    IVSHMEM_DPRINTF("eventfds[%ld] = %d\n", incoming_posn, incoming_fd);
+    s->eventfds[incoming_posn] = incoming_fd;
+
+    /* bitmap to keep track of live VMs */
+    s->eventfd_bitvec |= 1 << incoming_posn;
+
+    /* keep track of the maximum VM ID */
+    if (incoming_posn > s->num_eventfds) {
+        s->num_eventfds = incoming_posn;
+    }
+
+    /* initialize char device for callback on my eventfd */
+    if (incoming_posn == s->eventfd_posn) {
+        s->eventfd_chr = create_eventfd_chr_device(s, s->eventfds[s->eventfd_posn]);
+    }
+
+    return;
+}
+
+#if 0
+static void ivshmem_recvmsg(void *opaque, struct msghdr * msg, int flags)
+{
+
+    IVShmemState *s = opaque;
+    struct cmsghdr *cmptr;
+    struct iovec *iov;
+    long param;
+    long msg_size;
+
+    iov = msg->msg_iov;
+
+    memcpy(&param, iov->iov_base, sizeof param);
+
+    IVSHMEM_DPRINTF("Inside Recvmsg (%ld)\n", param);
+    for (cmptr = CMSG_FIRSTHDR(msg); cmptr != NULL;
+        cmptr = CMSG_NXTHDR(msg, cmptr)) {
+        if (cmptr->cmsg_level != SOL_SOCKET ||
+            cmptr->cmsg_type != SCM_RIGHTS) {
+                printf("read msg_size = %ld\n", msg_size);
+                continue;
+        }
+
+        // is eventfd_posn uninitialized?  Then this is the initial list of eventfds
+        if (s->eventfd_posn == -1) {
+
+            s->eventfd_bitvec = 0;
+            msg_size = sizeof(int) * (param + 1);
+            s->eventfds = (int *)malloc(msg_size);
+            s->num_eventfds = param + 1;
+            s->eventfd_posn = param;
+
+            memcpy(s->eventfds, CMSG_DATA(cmptr), msg_size);
+            IVSHMEM_DPRINTF("I am %d, receiving %d fds\n", s->eventfd_posn, s->num_eventfds);
+            IVSHMEM_DPRINTF("broadcast enabled - %d\n", BROADCAST_VAL);
+            IVSHMEM_DPRINTF("shmemfd is %d\n", s->eventfds[0]);
+            IVSHMEM_DPRINTF("My fd is %d\n", s->eventfds[s->eventfd_posn]);
+
+            /* presume all eventfds are live, we will be notified of dead ones */
+            s->eventfd_bitvec = (1 << (s->num_eventfds)) - 1;
+            s->eventfd_bitvec &= ~1; /* posn 0 is not an eventfd, it's the shared memory fd */
+
+            if (check_shm_size(s, s->eventfds[0]) == -1) {
+                exit(-1);
+            }
+
+            if (mmap(s->ivshmem_ptr, ivshmem_desc.size, PROT_READ|PROT_WRITE,
+                        MAP_SHARED|MAP_FIXED, s->eventfds[0], 0) == MAP_FAILED)
+            {
+                fprintf(stderr, "kvm_ivshmem: could not mmap shared file\n");
+                exit(-1);
+            }
+
+
+            // initialize char device for callback on my eventfd
+            s->eventfd_chr = create_eventfd_chr_device(s, s->eventfds[s->eventfd_posn]);
+
+            return;
+        }
+
+        // at this point we know this is an update
+        // the param is then the position of a new fd
+        if (param >= s->num_eventfds) {
+            s->eventfds = realloc(s->eventfds, sizeof(int) * (param + 1));
+        }
+
+        msg_size = sizeof(int);
+
+        // copy the new fd into its posn
+        memcpy(&(s->eventfds[param]), CMSG_DATA(cmptr), msg_size);
+
+        s->num_eventfds = param + 1;
+        s->eventfd_bitvec |= 1 << param;
+
+        IVSHMEM_DPRINTF("[update] new bitvec is %d\n", s->eventfd_bitvec);
+        IVSHMEM_DPRINTF("[update] s->eventfds[%ld] is %d\n", param,s->eventfds[param]);
+
+    }
+
+    // notification of a dead guest
+    // a negative number indicates a kill
+
+    if (param < 0) {
+        int index = -param;
+
+        IVSHMEM_DPRINTF("%d < %d || %d > 0\n", index, s->eventfds[index], s->num_eventfds);
+        if ((index < s->num_eventfds) || (s->eventfds[index] > 0)) {
+            s->eventfds[index] = -1;
+            // turn off the bit in the bit vector
+            s->eventfd_bitvec &= ~(1 << index);
+            IVSHMEM_DPRINTF("[kill] s->eventfds[%d] is %d\n", index,s->eventfds[index]);
+        }
+
+        return;
+
+    }
+
+}
+#endif
+
+int pci_ivshmem_init(PCIBus *bus)
+{
+    PCI_IVShmemState *d;
+    IVShmemState *s;
+    uint8_t *pci_conf;
+
+    IVSHMEM_DPRINTF("shared file is %s\n", ivshmem_desc.name);
+    d = (PCI_IVShmemState *)pci_register_device(bus, "kvm_ivshmem",
+                                           sizeof(PCI_IVShmemState),
+                                           -1, NULL, NULL);
+    if (!d) {
+        return -1;
+    }
+
+    s = &d->ivshmem_state;
+
+    /* allocate shared memory RAM */
+    s->ivshmem_offset = qemu_ram_alloc(ivshmem_desc.size);
+    IVSHMEM_DPRINTF("size is = %d\n", ivshmem_desc.size);
+    IVSHMEM_DPRINTF("ivshmem ram offset = %ld\n", s->ivshmem_offset);
+
+    s->ivshmem_ptr = qemu_get_ram_ptr(s->ivshmem_offset);
+
+    s->pci_dev = &d->dev;
+    s->ivshmem_size = ivshmem_desc.size;
+
+    pci_conf = d->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_IOACCESS | PCI_COMMAND_MEMACCESS;
+    pci_conf[0x0a] = 0x00; // RAM controller
+    pci_conf[0x0b] = 0x05;
+    pci_conf[0x0e] = 0x00; // header_type
+
+    pci_conf[PCI_INTERRUPT_PIN] = 1; // we are going to support interrupts
+
+    /* XXX: ivshmem_desc.size must be a power of two */
+
+    s->ivshmem_mmio_io_addr = cpu_register_io_memory(ivshmem_mmio_read,
+                                    ivshmem_mmio_write, s);
+
+    /* region for registers*/
+    pci_register_bar(&d->dev, 0, 0x100,
+                           PCI_BASE_ADDRESS_SPACE_MEMORY, ivshmem_mmio_map);
+
+    /* region for shared memory */
+    pci_register_bar(&d->dev, 1, ivshmem_desc.size,
+                           PCI_BASE_ADDRESS_SPACE_MEMORY, ivshmem_map);
+
+    if (ivshmem_desc.chrdev != NULL) {
+        if (strncmp(ivshmem_desc.chrdev, "unix:", 5) == 0) {
+
+            /* if we get a UNIX socket as the parameter we will talk
+             * to the ivshmem server*/
+            char label[32];
+
+            s->eventfd_posn = -1;
+
+            snprintf(label, 32, "ivshmem_chardev");
+            s->chr = qemu_chr_open(label, ivshmem_desc.chrdev, NULL);
+            if (s->chr == NULL) {
+                fprintf(stderr, "No server listening on %s\n",
+                                                        ivshmem_desc.chrdev);
+                exit(-1);
+            }
+
+//            tcp_switch_to_recvmsg_handlers(s->chr);
+
+            qemu_chr_add_handlers(s->chr, ivshmem_can_receive, ivshmem_read,
+                              ivshmem_event, s);
+        } else {
+            /* just map the file, we're not using a server */
+            int shmem_fd;
+
+            if ((shmem_fd=shm_open(ivshmem_desc.chrdev, O_CREAT|O_RDWR,
+                            S_IRWXU|S_IRWXG|S_IRWXO)) < 0) {
+                fprintf(stderr, "kvm_shmem: could not open shared file\n");
+                exit(-1);
+            }
+
+            /* mmap onto PCI device's memory */
+            if (ftruncate(shmem_fd, ivshmem_desc.size) != 0) {
+                fprintf(stderr, "kvm_ivshmem: could not truncate shared file\n");
+            }
+            if (mmap(s->ivshmem_ptr, ivshmem_desc.size, PROT_READ|PROT_WRITE,
+                        MAP_SHARED|MAP_FIXED, shmem_fd, 0)  == MAP_FAILED) {
+                fprintf(stderr, "kvm_ivshmem: could not mmap shared file\n");
+                exit(-1);
+            }
+        }
+    }
+
+    return 0;
+}
+
diff --git a/hw/pc.c b/hw/pc.c
index dc935a8..5dacc77 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -74,6 +74,8 @@  static PCII440FXState *i440fx_state;
 
 qemu_irq *ioapic_irq_hack;
 
+extern int ivshmem_enabled;
+
 typedef struct isa_irq_state {
     qemu_irq *i8259;
     qemu_irq *ioapic;
@@ -938,6 +940,10 @@  static void pc_init1(ram_addr_t ram_size,
         }
     }
 
+    if (pci_enabled && ivshmem_enabled) {
+        pci_ivshmem_init(pci_bus);
+    }
+
     rtc_state = rtc_init(2000);
 
     qemu_register_boot_set(pc_boot_set, rtc_state);
diff --git a/hw/pc.h b/hw/pc.h
index e9da683..4a75c96 100644
--- a/hw/pc.h
+++ b/hw/pc.h
@@ -167,6 +167,9 @@  void isa_ne2000_init(int base, int irq, NICInfo *nd);
 
 void extboot_init(BlockDriverState *bs);
 
+/* ivshmem.c */
+int pci_ivshmem_init(PCIBus *bus);
+
 int cpu_is_bsp(CPUState *env);
 
 #endif
diff --git a/qemu-char.c b/qemu-char.c
index 75dbf66..6e957b7 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -1706,6 +1706,7 @@  static CharDriverState *qemu_chr_open_win_pipe(QemuOpts *opts)
     WinCharState *s;
 
     chr = qemu_mallocz(sizeof(CharDriverState));
+
     s = qemu_mallocz(sizeof(WinCharState));
     chr->opaque = s;
     chr->chr_write = win_chr_write;
@@ -2049,6 +2050,12 @@  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 bcc0766..9a0d2c0 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-options.hx b/qemu-options.hx
index 9683d09..6a37083 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1679,6 +1679,18 @@  STEXI
 Setup monitor on chardev @var{name}.
 ETEXI
 
+DEF("ivshmem", HAS_ARG, QEMU_OPTION_ivshmem, \
+    "-ivshmem size,unix:file connects to shared memory PCI card server \
+    listening on unix domain socket 'path' of at least 'size' (in MB) and \
+    exposes  as a PCI device in the guest\n")
+STEXI
+@item -ivshmem @var{size},unix:@var{file}
+Connects to a shared memory PCI server at UDS @var{file} that shares a POSIX
+shared object of size @var{size} and creates a PCI device of the same size that
+maps the shared object (received from the server) into the device for guests to
+access.  The servers also sends eventfds to the guest to support interrupts.
+ETEXI
+
 DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \
     "-debugcon dev   redirect the debug console to char device 'dev'\n")
 STEXI
diff --git a/sysemu.h b/sysemu.h
index ff97786..9bf15b1 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -237,6 +237,14 @@  extern CharDriverState *serial_hds[MAX_SERIAL_PORTS];
 
 extern CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
 
+/* inter-VM shared memory devices */
+
+#define MAX_IVSHMEM_DEVICES 1
+
+extern CharDriverState * ivshmem_chardev;
+void ivshmem_init(const char * optarg);
+int ivshmem_get_size(void);
+
 #define TFR(expr) do { if ((expr) != -1) break; } while (errno == EINTR)
 
 #ifdef HAS_AUDIO
diff --git a/vl.c b/vl.c
index f7f388f..c7f6cf7 100644
--- a/vl.c
+++ b/vl.c
@@ -195,6 +195,7 @@  int autostart;
 static int rtc_utc = 1;
 static int rtc_date_offset = -1; /* -1 means no change */
 QEMUClock *rtc_clock;
+int ivshmem_enabled = 0;
 int vga_interface_type = VGA_NONE;
 #ifdef TARGET_SPARC
 int graphic_width = 1024;
@@ -213,6 +214,8 @@  int no_quit = 0;
 CharDriverState *serial_hds[MAX_SERIAL_PORTS];
 CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
 CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
+CharDriverState *ivshmem_chardev;
+const char * ivshmem_device;
 #ifdef TARGET_I386
 int win2k_install_hack = 0;
 int rtc_td_hack = 0;
@@ -4885,6 +4888,8 @@  int main(int argc, char **argv, char **envp)
     kernel_cmdline = "";
     cyls = heads = secs = 0;
     translation = BIOS_ATA_TRANSLATION_AUTO;
+    ivshmem_device = NULL;
+    ivshmem_chardev = NULL;
 
     for (i = 0; i < MAX_NODES; i++) {
         node_mem[i] = 0;
@@ -5366,6 +5371,10 @@  int main(int argc, char **argv, char **envp)
                 add_device_config(DEV_PARALLEL, optarg);
                 default_parallel = 0;
                 break;
+            case QEMU_OPTION_ivshmem:
+                ivshmem_device = optarg;
+                ivshmem_enabled = 1;
+                break;
             case QEMU_OPTION_debugcon:
                 add_device_config(DEV_DEBUGCON, optarg);
                 break;
@@ -5883,6 +5892,10 @@  int main(int argc, char **argv, char **envp)
     if (ram_size == 0)
         ram_size = DEFAULT_RAM_SIZE * 1024 * 1024;
 
+    if (ivshmem_enabled) {
+        ivshmem_init(ivshmem_device);
+    }
+
     /* init the dynamic translator */
     cpu_exec_init_all(tb_size * 1024 * 1024);