diff options
| -rw-r--r-- | Makefile.target | 3 | ||||
| -rw-r--r-- | hw/ivshmem.c | 828 | ||||
| -rw-r--r-- | qemu-char.c | 6 | ||||
| -rw-r--r-- | qemu-char.h | 3 | ||||
| -rw-r--r-- | qemu-doc.texi | 43 |
5 files changed, 883 insertions, 0 deletions
diff --git a/Makefile.target b/Makefile.target index 8a9c427b55..b791492897 100644 --- a/Makefile.target +++ b/Makefile.target @@ -190,6 +190,9 @@ 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 0000000000..bbb5cbaa16 --- /dev/null +++ b/hw/ivshmem.c @@ -0,0 +1,828 @@ +/* + * Inter-VM Shared Memory PCI device. + * + * Author: + * Cam Macdonell <cam@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) { + 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)) { + if (kvm_set_ioeventfd_mmio_long(incoming_fd, s->mmio_addr + DOORBELL, + (incoming_posn << 16) | guest_max_eventfd, 1) < 0) { + fprintf(stderr, "ivshmem: ioeventfd not available\n"); + } + } + + 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); + } + + /* allocate Qemu char devices for receiving interrupts */ + 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 9b69d928ef..6a3952ccdf 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 e3a07838a4..6ea01ba179 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 e67bf44ff3..55a966fe71 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 |