Hi On Mon, Mar 7, 2016 at 8:25 PM, Markus Armbruster <arm...@redhat.com> wrote: > 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. > > Signed-off-by: Markus Armbruster <arm...@redhat.com> > --- > hw/misc/ivshmem.c | 79 > ++++++++++++++++--------------------------------------- > 1 file changed, 23 insertions(+), 56 deletions(-) > > diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c > index 1c25621..747f9c3 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(s->ivshmem.ram_addr, 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, > @@ -833,6 +809,23 @@ 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); > @@ -911,6 +904,10 @@ 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; > > @@ -921,7 +918,7 @@ 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); > > @@ -948,36 +945,6 @@ 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) {
Nice patch, but it's worth pointing out that qemu file_ram_alloc() creates file with open O_CREAT. Here you rely on the fact that /dev/shm is present and file inside maps to POSIX shared memory object names. That's a lot more restrictive than using shm_open(). Furthermore, the permissions are not the same. The current code uses 777 for some reasons, while qemu file_ram_alloc() is 644. I am not convinced the cleanup is worth these braking changes, especially the restriction to Linux only. > - /* 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) { > -- > 2.4.3 > > -- Marc-André Lureau