From 08c7517e5c5eb270ee068db6480def1fe35bddf1 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Tue, 15 Mar 2016 19:34:46 +0100 Subject: ivshmem: Implement shm=... with a memory backend ivshmem has its very own code to create and map shared memory. Replace that with an implicitly created memory backend. Reduces the number of ways we create BAR 2 from three to two. The memory-backend-file is currently available only with CONFIG_LINUX, so this adds a second Linuxism to ivshmem (the other one is eventfd). Should we ever need to make it portable to systems where memory-backend-file can't be made to serve, we could create a memory-backend-shmem that allocates memory with shm_open(). Bonus fix: shared memory files are now created with permissions 0655 instead of 0777. Signed-off-by: Markus Armbruster Reviewed-by: Paolo Bonzini Message-Id: <1458066895-20632-32-git-send-email-armbru@redhat.com> --- hw/misc/ivshmem.c | 79 ++++++++++++++++--------------------------------------- 1 file changed, 23 insertions(+), 56 deletions(-) (limited to 'hw/misc') diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c index 66c713e..138ae9d 100644 --- a/hw/misc/ivshmem.c +++ b/hw/misc/ivshmem.c @@ -26,6 +26,7 @@ #include "migration/migration.h" #include "qemu/error-report.h" #include "qemu/event_notifier.h" +#include "qom/object_interfaces.h" #include "sysemu/char.h" #include "sysemu/hostmem.h" #include "qapi/visitor.h" @@ -369,31 +370,6 @@ static int check_shm_size(IVShmemState *s, int fd, Error **errp) } } -/* create the shared memory BAR when we are not using the server, so we can - * create the BAR and map the memory immediately */ -static int create_shared_memory_BAR(IVShmemState *s, int fd, uint8_t attr, - Error **errp) -{ - void * ptr; - - ptr = mmap(0, s->ivshmem_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); - if (ptr == MAP_FAILED) { - error_setg_errno(errp, errno, "Failed to mmap shared memory"); - return -1; - } - - memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s), "ivshmem.bar2", - s->ivshmem_size, ptr); - qemu_set_ram_fd(memory_region_get_ram_addr(&s->ivshmem), fd); - vmstate_register_ram(&s->ivshmem, DEVICE(s)); - memory_region_add_subregion(&s->bar, 0, &s->ivshmem); - - /* region for shared memory */ - pci_register_bar(PCI_DEVICE(s), 2, attr, &s->bar); - - return 0; -} - static void ivshmem_add_eventfd(IVShmemState *s, int posn, int i) { memory_region_add_eventfd(&s->ivshmem_mmio, @@ -837,6 +813,23 @@ static void ivshmem_write_config(PCIDevice *pdev, uint32_t address, } } +static void desugar_shm(IVShmemState *s) +{ + Object *obj; + char *path; + + obj = object_new("memory-backend-file"); + path = g_strdup_printf("/dev/shm/%s", s->shmobj); + object_property_set_str(obj, path, "mem-path", &error_abort); + g_free(path); + object_property_set_int(obj, s->ivshmem_size, "size", &error_abort); + object_property_set_bool(obj, true, "share", &error_abort); + object_property_add_child(OBJECT(s), "internal-shm-backend", obj, + &error_abort); + user_creatable_complete(obj, &error_abort); + s->hostmem = MEMORY_BACKEND(obj); +} + static void pci_ivshmem_realize(PCIDevice *dev, Error **errp) { IVShmemState *s = IVSHMEM(dev); @@ -915,6 +908,10 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error **errp) attr |= PCI_BASE_ADDRESS_MEM_TYPE_64; } + if (s->shmobj) { + desugar_shm(s); + } + if (s->hostmem != NULL) { MemoryRegion *mr; @@ -925,7 +922,7 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error **errp) vmstate_register_ram(mr, DEVICE(s)); memory_region_add_subregion(&s->bar, 0, mr); pci_register_bar(PCI_DEVICE(s), 2, attr, &s->bar); - } else if (s->server_chr != NULL) { + } else { IVSHMEM_DPRINTF("using shared memory server (socket = %s)\n", s->server_chr->filename); @@ -952,36 +949,6 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error **errp) error_setg(errp, "failed to initialize interrupts"); return; } - } else { - /* just map the file immediately, we're not using a server */ - int fd; - - 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) { - error_report("could not truncate shared file"); - } - - } else if ((fd = shm_open(s->shmobj, O_CREAT|O_RDWR, - S_IRWXU|S_IRWXG|S_IRWXO)) < 0) { - error_setg(errp, "could not open shared file"); - return; - } - - if (check_shm_size(s, fd, errp) == -1) { - return; - } - - create_shared_memory_BAR(s, fd, attr, &err); - if (err) { - error_propagate(errp, err); - return; - } } if (s->role_val == IVSHMEM_PEER) { -- cgit v1.1