On Fri, May 12, 2023 at 9:51 PM Viktor Prutyanov <vik...@daynix.com> wrote:
>
> The guest can disable or never enable Device-TLB. In these cases,
> it can't be used even if enabled in QEMU. So, check Device-TLB state
> before registering IOMMU notifier and select unmap flag depending on
> that. Also, implement a way to change IOMMU notifier flag if Device-TLB
> state is changed.
>
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2001312
> Signed-off-by: Viktor Prutyanov <vik...@daynix.com>
> ---
> hw/virtio/vhost-backend.c | 6 ++++++
> hw/virtio/vhost.c | 30 ++++++++++++++++++------------
> include/hw/virtio/vhost-backend.h | 3 +++
> include/hw/virtio/vhost.h | 1 +
> 4 files changed, 28 insertions(+), 12 deletions(-)
>
> diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c
> index 8e581575c9..d39bfefd2d 100644
> --- a/hw/virtio/vhost-backend.c
> +++ b/hw/virtio/vhost-backend.c
> @@ -297,6 +297,11 @@ 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_toggle_device_iotlb(struct vhost_dev *dev)
> +{
> + vhost_toggle_device_iotlb(dev);
> +}
> +
> const VhostOps kernel_ops = {
> .backend_type = VHOST_BACKEND_TYPE_KERNEL,
> .vhost_backend_init = vhost_kernel_init,
> @@ -328,6 +333,7 @@ const VhostOps kernel_ops = {
> .vhost_vsock_set_running = vhost_kernel_vsock_set_running,
> .vhost_set_iotlb_callback = vhost_kernel_set_iotlb_callback,
> .vhost_send_device_iotlb_msg = vhost_kernel_send_device_iotlb_msg,
> + .vhost_toggle_device_iotlb = vhost_kernel_toggle_device_iotlb,
> };
> #endif
>
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 746d130c74..41c9fbf286 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -781,7 +781,6 @@ static void vhost_iommu_region_add(MemoryListener
> *listener,
> Int128 end;
> int iommu_idx;
> IOMMUMemoryRegion *iommu_mr;
> - int ret;
>
> if (!memory_region_is_iommu(section->mr)) {
> return;
> @@ -796,7 +795,9 @@ static void vhost_iommu_region_add(MemoryListener
> *listener,
> iommu_idx = memory_region_iommu_attrs_to_index(iommu_mr,
> MEMTXATTRS_UNSPECIFIED);
> iommu_notifier_init(&iommu->n, vhost_iommu_unmap_notify,
> - IOMMU_NOTIFIER_DEVIOTLB_UNMAP,
> + dev->vdev->device_iotlb_enabled ?
> + IOMMU_NOTIFIER_DEVIOTLB_UNMAP :
> + IOMMU_NOTIFIER_UNMAP,
> section->offset_within_region,
> int128_get64(end),
> iommu_idx);
> @@ -804,16 +805,8 @@ static void vhost_iommu_region_add(MemoryListener
> *listener,
> iommu->iommu_offset = section->offset_within_address_space -
> section->offset_within_region;
> iommu->hdev = dev;
> - ret = memory_region_register_iommu_notifier(section->mr, &iommu->n,
> NULL);
> - if (ret) {
> - /*
> - * Some vIOMMUs do not support dev-iotlb yet. If so, try to use the
> - * UNMAP legacy message
> - */
> - iommu->n.notifier_flags = IOMMU_NOTIFIER_UNMAP;
> - memory_region_register_iommu_notifier(section->mr, &iommu->n,
> - &error_fatal);
> - }
So we lose this fallback. Is this really intended?
E.g does it work if you are using virtio-iommu?
Thanks
> + memory_region_register_iommu_notifier(section->mr, &iommu->n,
> + &error_fatal);
> QLIST_INSERT_HEAD(&dev->iommu_list, iommu, iommu_next);
> /* TODO: can replay help performance here? */
> }
> @@ -841,6 +834,19 @@ static void vhost_iommu_region_del(MemoryListener
> *listener,
> }
> }
>
> +void vhost_toggle_device_iotlb(struct vhost_dev *dev)
> +{
> + struct vhost_iommu *iommu;
> +
> + QLIST_FOREACH(iommu, &dev->iommu_list, iommu_next) {
> + memory_region_unregister_iommu_notifier(iommu->mr, &iommu->n);
> + iommu->n.notifier_flags = dev->vdev->device_iotlb_enabled ?
> + IOMMU_NOTIFIER_DEVIOTLB_UNMAP : IOMMU_NOTIFIER_UNMAP;
> + memory_region_register_iommu_notifier(iommu->mr, &iommu->n,
> + &error_fatal);
> + }
> +}
> +
> static int vhost_virtqueue_set_addr(struct vhost_dev *dev,
> struct vhost_virtqueue *vq,
> unsigned idx, bool enable_log)
> diff --git a/include/hw/virtio/vhost-backend.h
> b/include/hw/virtio/vhost-backend.h
> index ec3fbae58d..10a3c36b4b 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -133,6 +133,8 @@ typedef int (*vhost_set_config_call_op)(struct vhost_dev
> *dev,
>
> typedef void (*vhost_reset_status_op)(struct vhost_dev *dev);
>
> +typedef void (*vhost_toggle_device_iotlb_op)(struct vhost_dev *dev);
> +
> typedef struct VhostOps {
> VhostBackendType backend_type;
> vhost_backend_init vhost_backend_init;
> @@ -181,6 +183,7 @@ typedef struct VhostOps {
> vhost_force_iommu_op vhost_force_iommu;
> vhost_set_config_call_op vhost_set_config_call;
> vhost_reset_status_op vhost_reset_status;
> + vhost_toggle_device_iotlb_op vhost_toggle_device_iotlb;
> } VhostOps;
>
> int vhost_backend_update_device_iotlb(struct vhost_dev *dev,
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index a52f273347..785832ed46 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -320,6 +320,7 @@ bool vhost_has_free_slot(void);
> int vhost_net_set_backend(struct vhost_dev *hdev,
> struct vhost_vring_file *file);
>
> +void vhost_toggle_device_iotlb(struct vhost_dev *dev);
> int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write);
>
> int vhost_virtqueue_start(struct vhost_dev *dev, struct VirtIODevice *vdev,
> --
> 2.35.1
>
