vhost: add vhost_has_free_slot() interface 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 <imammedo@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c index 72d1392..910d8e0 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> @@ -49,12 +50,30 @@ return idx - dev->vq_index; } +static int vhost_kernel_memslots_limit(struct vhost_dev *dev) +{ + int limit = 64; + char *s; + + if (g_file_get_contents("/sys/module/vhost/parameters/max_mem_regions", + &s, NULL, NULL)) { + uint64_t val = g_ascii_strtoull(s, NULL, 10); + if (!((val == G_MAXUINT64 || !val) && errno)) { + return val; + } + error_report("ignoring invalid max_mem_regions value in vhost module:" + " %s", s); + } + 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_get_vq_index = vhost_kernel_get_vq_index, + .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 b11c0d2..9585637 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c
@@ -440,6 +440,11 @@ return idx; } +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, @@ -447,4 +452,5 @@ .vhost_backend_cleanup = vhost_user_cleanup, .vhost_backend_get_vq_index = vhost_user_get_vq_index, .vhost_backend_set_vring_enable = vhost_user_set_vring_enable, + .vhost_backend_memslots_limit = vhost_user_memslots_limit, };
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index c0ed5b2..a3b4f9e 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c
@@ -26,6 +26,22 @@ static struct vhost_log *vhost_log; +static unsigned int used_memslots; +static QLIST_HEAD(, vhost_dev) vhost_devices = + QLIST_HEAD_INITIALIZER(vhost_devices); + +bool vhost_has_free_slot(void) +{ + unsigned int slots_limit = ~0U; + struct vhost_dev *hdev; + + QLIST_FOREACH(hdev, &vhost_devices, entry) { + unsigned int r = hdev->vhost_ops->vhost_backend_memslots_limit(hdev); + slots_limit = MIN(slots_limit, r); + } + return slots_limit > used_memslots; +} + static void vhost_dev_sync_region(struct vhost_dev *dev, MemoryRegionSection *section, uint64_t mfirst, uint64_t mlast, @@ -457,6 +473,7 @@ 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) @@ -916,6 +933,8 @@ return -errno; } + QLIST_INSERT_HEAD(&vhost_devices, hdev, entry); + r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_OWNER, NULL); if (r < 0) { goto fail; @@ -972,6 +991,7 @@ fail: r = -errno; hdev->vhost_ops->vhost_backend_cleanup(hdev); + QLIST_REMOVE(hdev, entry); return r; } @@ -989,6 +1009,7 @@ g_free(hdev->mem); g_free(hdev->mem_sections); hdev->vhost_ops->vhost_backend_cleanup(hdev); + QLIST_REMOVE(hdev, entry); } /* Stop processing guest IO notifications in qemu.
diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h index 3a0f6e2..7d4a8ad 100644 --- a/include/hw/virtio/vhost-backend.h +++ b/include/hw/virtio/vhost-backend.h
@@ -26,6 +26,7 @@ typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev); typedef int (*vhost_backend_get_vq_index)(struct vhost_dev *dev, int idx); typedef int (*vhost_backend_set_vring_enable)(struct vhost_dev *dev, int enable); +typedef int (*vhost_backend_memslots_limit)(struct vhost_dev *dev); typedef struct VhostOps { VhostBackendType backend_type; @@ -34,6 +35,7 @@ vhost_backend_cleanup vhost_backend_cleanup; vhost_backend_get_vq_index vhost_backend_get_vq_index; vhost_backend_set_vring_enable vhost_backend_set_vring_enable; + 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 c3758f3..080831e 100644 --- a/include/hw/virtio/vhost.h +++ b/include/hw/virtio/vhost.h
@@ -59,6 +59,7 @@ const VhostOps *vhost_ops; void *opaque; struct vhost_log *log; + QLIST_ENTRY(vhost_dev) entry; }; int vhost_dev_init(struct vhost_dev *hdev, void *opaque, @@ -83,4 +84,5 @@ 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 85e4e81..ce6ce11 100644 --- a/stubs/Makefile.objs +++ b/stubs/Makefile.objs
@@ -39,3 +39,4 @@ stub-obj-y += kvm.o stub-obj-y += qmp_pc_dimm_device_list.o stub-obj-y += target-monitor-defs.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; +}