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Re: [Qemu-devel] [PATCH 29/38] ivshmem: Implement shm=... with a memory
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 29/38] ivshmem: Implement shm=... with a memory backend |
Date: |
Tue, 1 Mar 2016 12:37:59 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0 |
On 29/02/2016 19:40, Markus Armbruster 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 <address@hidden>
Very appreciated, but do not use user_creatable_add_opts. Instead,
create the object with object_initialize, object_property_set_* and
user_creatable_complete. After the object_initialize, add it with
object_property_add_child *under the ivshmem device itself*, giving it a
name like "internal-shm-backend".
This matches what virtio-blk dataplane used to do for x-dataplane (now
removed).
Thanks,
Paolo
> +static HostMemoryBackend *desugar_shm(const char *shm, size_t size)
> +{
> + /* TODO avoid the detour through QemuOpts */
> + static int counter;
> + QemuOpts *opts = qemu_opts_create(qemu_find_opts("object"),
> + NULL, 0, &error_abort);
> + char *path;
> + Object *obj;
> +
> + qemu_opt_set(opts, "qom-type", "memory-backend-file",
> + &error_abort);
> + /* FIXME need a better way to make up an ID */
> + qemu_opts_set_id(opts, g_strdup_printf("ivshmem-backend-%d", counter++));
> + path = g_strdup_printf("/dev/shm/%s", shm);
> + qemu_opt_set(opts, "mem-path", path, &error_abort);
> + qemu_opt_set_number(opts, "size", size, &error_abort);
> + qemu_opt_set_bool(opts, "share", true, &error_abort);
> + g_free(path);
> +
> + obj = user_creatable_add_opts(opts, &error_abort);
> + qemu_opts_del(opts);
> +
> + user_creatable_complete(obj, &error_abort);
> +
> + return MEMORY_BACKEND(obj);
> +}
> +
> static void pci_ivshmem_realize(PCIDevice *dev, Error **errp)
> {
> IVShmemState *s = IVSHMEM(dev);
> @@ -911,6 +914,10 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error
> **errp)
> attr |= PCI_BASE_ADDRESS_MEM_TYPE_64;
> }
>
> + if (s->shmobj) {
> + s->hostmem = desugar_shm(s->shmobj, s->ivshmem_size);
> + }
> +
> if (s->hostmem != NULL) {
> MemoryRegion *mr;
>
> @@ -921,7 +928,7 @@ 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 +955,6 @@ 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) {
>
- Re: [Qemu-devel] [PATCH 29/38] ivshmem: Implement shm=... with a memory backend,
Paolo Bonzini <=