it will allow for other parts of QEMU check if it's safe to map memory region during hotplug/runtime. That way hotplug path will have a chance to cancel hotplug operation instead of crashing in vhost_commit().
Signed-off-by: Igor Mammedov <imamm...@redhat.com> --- hw/virtio/vhost-backend.c | 23 ++++++++++++++++++++++- hw/virtio/vhost-user.c | 8 +++++++- hw/virtio/vhost.c | 21 +++++++++++++++++++++ include/hw/virtio/vhost-backend.h | 2 ++ include/hw/virtio/vhost.h | 1 + stubs/Makefile.objs | 1 + stubs/vhost.c | 6 ++++++ 7 files changed, 60 insertions(+), 2 deletions(-) create mode 100644 stubs/vhost.c diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c index 4d68a27..46fa707 100644 --- a/hw/virtio/vhost-backend.c +++ b/hw/virtio/vhost-backend.c @@ -11,6 +11,7 @@ #include "hw/virtio/vhost.h" #include "hw/virtio/vhost-backend.h" #include "qemu/error-report.h" +#include "linux/vhost.h" #include <sys/ioctl.h> @@ -42,11 +43,31 @@ static int vhost_kernel_cleanup(struct vhost_dev *dev) return close(fd); } +static int vhost_kernel_memslots_limit(struct vhost_dev *dev) +{ + int limit; + int s = offsetof(struct vhost_memory, regions); + struct vhost_memory *mem = g_malloc0(s); + + assert(dev->mem->nregions); + do { + s += sizeof mem->regions[0]; + mem = g_realloc(mem, s); + mem->regions[mem->nregions] = dev->mem->regions[0]; + mem->nregions++; + } while (vhost_kernel_call(dev, VHOST_SET_MEM_TABLE, mem) != -1); + limit = mem->nregions - 1 > 0 ? mem->nregions - 1 : 0; + g_free(mem); + + return limit; +} + static const VhostOps kernel_ops = { .backend_type = VHOST_BACKEND_TYPE_KERNEL, .vhost_call = vhost_kernel_call, .vhost_backend_init = vhost_kernel_init, - .vhost_backend_cleanup = vhost_kernel_cleanup + .vhost_backend_cleanup = vhost_kernel_cleanup, + .vhost_backend_memslots_limit = vhost_kernel_memslots_limit }; int vhost_set_backend_type(struct vhost_dev *dev, VhostBackendType backend_type) diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index d6f2163..0487809 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -352,9 +352,15 @@ static int vhost_user_cleanup(struct vhost_dev *dev) return 0; } +static int vhost_user_memslots_limit(struct vhost_dev *dev) +{ + return VHOST_MEMORY_MAX_NREGIONS; +} + const VhostOps user_ops = { .backend_type = VHOST_BACKEND_TYPE_USER, .vhost_call = vhost_user_call, .vhost_backend_init = vhost_user_init, - .vhost_backend_cleanup = vhost_user_cleanup + .vhost_backend_cleanup = vhost_user_cleanup, + .vhost_backend_memslots_limit = vhost_user_memslots_limit }; diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index 2712c6f..e964004 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -26,6 +26,18 @@ static struct vhost_log *vhost_log; +static int used_memslots; +static int memslots_limit = -1; + +bool vhost_has_free_slot(void) +{ + if (memslots_limit >= 0) { + return memslots_limit > used_memslots; + } + + return true; +} + static void vhost_dev_sync_region(struct vhost_dev *dev, MemoryRegionSection *section, uint64_t mfirst, uint64_t mlast, @@ -457,6 +469,7 @@ static void vhost_set_memory(MemoryListener *listener, dev->mem_changed_start_addr = MIN(dev->mem_changed_start_addr, start_addr); dev->mem_changed_end_addr = MAX(dev->mem_changed_end_addr, start_addr + size - 1); dev->memory_changed = true; + used_memslots = dev->mem->nregions; } static bool vhost_section(MemoryRegionSection *section) @@ -1119,6 +1132,14 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev) if (r < 0) { goto fail_features; } + + r = hdev->vhost_ops->vhost_backend_memslots_limit(hdev); + if (memslots_limit > 0) { + memslots_limit = MIN(memslots_limit, r); + } else { + memslots_limit = r; + } + r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_MEM_TABLE, hdev->mem); if (r < 0) { r = -errno; diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h index e472f29..28b6714 100644 --- a/include/hw/virtio/vhost-backend.h +++ b/include/hw/virtio/vhost-backend.h @@ -24,12 +24,14 @@ typedef int (*vhost_call)(struct vhost_dev *dev, unsigned long int request, void *arg); typedef int (*vhost_backend_init)(struct vhost_dev *dev, void *opaque); typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev); +typedef int (*vhost_backend_memslots_limit)(struct vhost_dev *dev); typedef struct VhostOps { VhostBackendType backend_type; vhost_call vhost_call; vhost_backend_init vhost_backend_init; vhost_backend_cleanup vhost_backend_cleanup; + vhost_backend_memslots_limit vhost_backend_memslots_limit; } VhostOps; extern const VhostOps user_ops; diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h index dd51050..17ff7b6 100644 --- a/include/hw/virtio/vhost.h +++ b/include/hw/virtio/vhost.h @@ -81,4 +81,5 @@ uint64_t vhost_get_features(struct vhost_dev *hdev, const int *feature_bits, uint64_t features); void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits, uint64_t features); +bool vhost_has_free_slot(void); #endif diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs index 9937a12..d2f1b21 100644 --- a/stubs/Makefile.objs +++ b/stubs/Makefile.objs @@ -38,3 +38,4 @@ stub-obj-$(CONFIG_WIN32) += fd-register.o stub-obj-y += cpus.o stub-obj-y += kvm.o stub-obj-y += qmp_pc_dimm_device_list.o +stub-obj-y += vhost.o diff --git a/stubs/vhost.c b/stubs/vhost.c new file mode 100644 index 0000000..d346b85 --- /dev/null +++ b/stubs/vhost.c @@ -0,0 +1,6 @@ +#include "hw/virtio/vhost.h" + +bool vhost_has_free_slot(void) +{ + return true; +} -- 1.8.3.1