On Fri, 29 Dec 2017 10:35:11 +0800
Jay Zhou <jianjay.z...@huawei.com> wrote:
> Used_memslots is equal to dev->mem->nregions now, it is true for
> vhost kernel, but not for vhost user, which uses the memory regions
> that have file descriptor. In fact, not all of the memory regions
> have file descriptor.
> It is usefully in some scenarios, e.g. used_memslots is 8, and only
> 5 memory slots can be used by vhost user, it is failed to hotplug
> a new DIMM memory because vhost_has_free_slot just returned false,
> however we can hotplug it safely in fact.
>
> Meanwhile, instead of asserting in vhost_user_set_mem_table(),
> error number is used to gracefully prevent device to start. This
> fixed the VM crash issue.
below mostly style related comments,
otherwise patch looks good to me
>
> Suggested-by: Igor Mammedov <imamm...@redhat.com>
> Signed-off-by: Jay Zhou <jianjay.z...@huawei.com>
> Signed-off-by: Zhe Liu <gary.liu...@huawei.com>
> ---
> hw/virtio/vhost-backend.c | 14 +++++++
> hw/virtio/vhost-user.c | 84
> +++++++++++++++++++++++++++++----------
> hw/virtio/vhost.c | 16 ++++----
> include/hw/virtio/vhost-backend.h | 4 ++
> 4 files changed, 91 insertions(+), 27 deletions(-)
>
> diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
> index 7f09efa..866718c 100644
> --- a/hw/virtio/vhost-backend.c
> +++ b/hw/virtio/vhost-backend.c
> @@ -15,6 +15,8 @@
> #include "hw/virtio/vhost-backend.h"
> #include "qemu/error-report.h"
>
> +static unsigned int vhost_kernel_used_memslots;
> +
> static int vhost_kernel_call(struct vhost_dev *dev, unsigned long int
> request,
> void *arg)
> {
> @@ -233,6 +235,16 @@ static void vhost_kernel_set_iotlb_callback(struct
> vhost_dev *dev,
> qemu_set_fd_handler((uintptr_t)dev->opaque, NULL, NULL, NULL);
> }
>
> +static void vhost_kernel_set_used_memslots(struct vhost_dev *dev)
> +{
> + vhost_kernel_used_memslots = dev->mem->nregions;
> +}
> +
> +static unsigned int vhost_kernel_get_used_memslots(void)
> +{
> + return vhost_kernel_used_memslots;
> +}
> +
> static const VhostOps kernel_ops = {
> .backend_type = VHOST_BACKEND_TYPE_KERNEL,
> .vhost_backend_init = vhost_kernel_init,
> @@ -264,6 +276,8 @@ static const VhostOps kernel_ops = {
> #endif /* CONFIG_VHOST_VSOCK */
> .vhost_set_iotlb_callback = vhost_kernel_set_iotlb_callback,
> .vhost_send_device_iotlb_msg = vhost_kernel_send_device_iotlb_msg,
> + .vhost_set_used_memslots = vhost_kernel_set_used_memslots,
> + .vhost_get_used_memslots = vhost_kernel_get_used_memslots,
> };
>
> 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 093675e..0f913be 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -122,6 +122,8 @@ static VhostUserMsg m __attribute__ ((unused));
> /* The version of the protocol we support */
> #define VHOST_USER_VERSION (0x1)
>
> +static unsigned int vhost_user_used_memslots;
> +
> struct vhost_user {
> CharBackend *chr;
> int slave_fd;
> @@ -289,12 +291,53 @@ static int vhost_user_set_log_base(struct vhost_dev
> *dev, uint64_t base,
> return 0;
> }
>
> +static int vhost_user_prepare_msg(struct vhost_dev *dev, VhostUserMsg *msg,
> + int *fds)
> +{
> + int r = 0;
> + int i, fd;
> + size_t fd_num = 0;
fd_num is redundant
you can use msg->payload.memory.nregions as a counter
> +
> + for (i = 0; i < dev->mem->nregions; ++i) {
for (i = 0, msg->payload.memory.nregions = 0; ...
> + struct vhost_memory_region *reg = dev->mem->regions + i;
> + ram_addr_t offset;
> + MemoryRegion *mr;
> +
> + assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
> + mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
> + &offset);
> + fd = memory_region_get_fd(mr);
> + if (fd > 0) {
> + if (fd_num < VHOST_MEMORY_MAX_NREGIONS) {
instead of shifting below block to the right, I'd write it like this:
if (msg->payload.memory.nregions == VHOST_MEMORY_MAX_NREGIONS) {
return -1;
}
> + msg->payload.memory.nregions++;
> + msg->payload.memory.regions[fd_num].userspace_addr =
> + reg->userspace_addr;
> + msg->payload.memory.regions[fd_num].memory_size =
> + reg->memory_size;
> + msg->payload.memory.regions[fd_num].guest_phys_addr =
> + reg->guest_phys_addr;
> + msg->payload.memory.regions[fd_num].mmap_offset = offset;
> + fds[fd_num] = fd;
> + } else {
> + r = -1;
> + }
> + fd_num++;
> + }
> + }
> +
> + /* Save the number of memory slots available for vhost user,
> + * vhost_user_get_used_memslots() can use it next time
> + */
> + vhost_user_used_memslots = fd_num;
> +
> + return r;
> +}
> +
> static int vhost_user_set_mem_table(struct vhost_dev *dev,
> struct vhost_memory *mem)
> {
> int fds[VHOST_MEMORY_MAX_NREGIONS];
> - int i, fd;
> - size_t fd_num = 0;
> + size_t fd_num;
> bool reply_supported = virtio_has_feature(dev->protocol_features,
>
> VHOST_USER_PROTOCOL_F_REPLY_ACK);
>
> @@ -307,26 +350,12 @@ static int vhost_user_set_mem_table(struct vhost_dev
> *dev,
> msg.flags |= VHOST_USER_NEED_REPLY_MASK;
> }
>
> - for (i = 0; i < dev->mem->nregions; ++i) {
> - struct vhost_memory_region *reg = dev->mem->regions + i;
> - ram_addr_t offset;
> - MemoryRegion *mr;
> -
> - assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
> - mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
> - &offset);
> - fd = memory_region_get_fd(mr);
> - if (fd > 0) {
> - msg.payload.memory.regions[fd_num].userspace_addr =
> reg->userspace_addr;
> - msg.payload.memory.regions[fd_num].memory_size =
> reg->memory_size;
> - msg.payload.memory.regions[fd_num].guest_phys_addr =
> reg->guest_phys_addr;
> - msg.payload.memory.regions[fd_num].mmap_offset = offset;
> - assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
> - fds[fd_num++] = fd;
> - }
> + if (vhost_user_prepare_msg(dev, &msg, fds) < 0) {
> + error_report("Failed preparing vhost-user memory table msg");
> + return -1;
> }
>
> - msg.payload.memory.nregions = fd_num;
> + fd_num = msg.payload.memory.nregions;
>
> if (!fd_num) {
> error_report("Failed initializing vhost-user memory map, "
> @@ -922,6 +951,19 @@ static void vhost_user_set_iotlb_callback(struct
> vhost_dev *dev, int enabled)
> /* No-op as the receive channel is not dedicated to IOTLB messages. */
> }
>
> +static void vhost_user_set_used_memslots(struct vhost_dev *dev)
> +{
> + int fds[VHOST_MEMORY_MAX_NREGIONS];
> + VhostUserMsg msg;
> +
> + vhost_user_prepare_msg(dev, &msg, fds);
> +}
> +
> +static unsigned int vhost_user_get_used_memslots(void)
> +{
> + return vhost_user_used_memslots;
> +}
> +
> const VhostOps user_ops = {
> .backend_type = VHOST_BACKEND_TYPE_USER,
> .vhost_backend_init = vhost_user_init,
> @@ -948,4 +990,6 @@ const VhostOps user_ops = {
> .vhost_net_set_mtu = vhost_user_net_set_mtu,
> .vhost_set_iotlb_callback = vhost_user_set_iotlb_callback,
> .vhost_send_device_iotlb_msg = vhost_user_send_device_iotlb_msg,
> + .vhost_set_used_memslots = vhost_user_set_used_memslots,
> + .vhost_get_used_memslots = vhost_user_get_used_memslots,
> };
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index e4290ce..59a32e9 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -43,20 +43,21 @@
> static struct vhost_log *vhost_log;
> static struct vhost_log *vhost_log_shm;
>
> -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);
> + if (hdev->vhost_ops->vhost_get_used_memslots() >=
> + hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
> + return false;
> + }
> }
> - return slots_limit > used_memslots;
> +
> + return true;
> }
>
> static void vhost_dev_sync_region(struct vhost_dev *dev,
> @@ -606,7 +607,7 @@ 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;
> + dev->vhost_ops->vhost_set_used_memslots(dev);
> }
>
> static bool vhost_section(MemoryRegionSection *section)
> @@ -1251,7 +1252,8 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
> goto fail;
> }
>
> - if (used_memslots > hdev->vhost_ops->vhost_backend_memslots_limit(hdev))
> {
> + if (hdev->vhost_ops->vhost_get_used_memslots() >
> + hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
> error_report("vhost backend memory slots limit is less"
> " than current number of present memory slots");
> r = -1;
> diff --git a/include/hw/virtio/vhost-backend.h
> b/include/hw/virtio/vhost-backend.h
> index a7a5f22..19961b5 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -84,6 +84,8 @@ typedef void (*vhost_set_iotlb_callback_op)(struct
> vhost_dev *dev,
> int enabled);
> typedef int (*vhost_send_device_iotlb_msg_op)(struct vhost_dev *dev,
> struct vhost_iotlb_msg *imsg);
> +typedef void (*vhost_set_used_memslots_op)(struct vhost_dev *dev);
> +typedef unsigned int (*vhost_get_used_memslots_op)(void);
>
> typedef struct VhostOps {
> VhostBackendType backend_type;
> @@ -118,6 +120,8 @@ typedef struct VhostOps {
> vhost_vsock_set_running_op vhost_vsock_set_running;
> vhost_set_iotlb_callback_op vhost_set_iotlb_callback;
> vhost_send_device_iotlb_msg_op vhost_send_device_iotlb_msg;
> + vhost_set_used_memslots_op vhost_set_used_memslots;
> + vhost_get_used_memslots_op vhost_get_used_memslots;
> } VhostOps;
>
> extern const VhostOps user_ops;
