Re: [PATCH v28 14/17] vfio: Dirty page tracking when vIOMMU is enabled

[Yan Zhao]

Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>

On Fri, Oct 23, 2020 at 04:10:40PM +0530, Kirti Wankhede wrote:
> When vIOMMU is enabled, add MAP notifier from log_sync when all
> devices in container are in stop and copy phase of migration. Call replay
> and then from notifier callback, get dirty pages.
> 
> Suggested-by: Alex Williamson <alex.williamson@redhat.com>
> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> ---
>  hw/vfio/common.c     | 88 
> ++++++++++++++++++++++++++++++++++++++++++++++++----
>  hw/vfio/trace-events |  1 +
>  2 files changed, 83 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 2634387df948..c0b5b6245a47 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -442,8 +442,8 @@ static bool 
> vfio_listener_skipped_section(MemoryRegionSection *section)
>  }
>  
>  /* Called with rcu_read_lock held.  */
> -static bool vfio_get_vaddr(IOMMUTLBEntry *iotlb, void **vaddr,
> -                           bool *read_only)
> +static bool vfio_get_xlat_addr(IOMMUTLBEntry *iotlb, void **vaddr,
> +                               ram_addr_t *ram_addr, bool *read_only)
>  {
>      MemoryRegion *mr;
>      hwaddr xlat;
> @@ -474,8 +474,17 @@ static bool vfio_get_vaddr(IOMMUTLBEntry *iotlb, void 
> **vaddr,
>          return false;
>      }
>  
> -    *vaddr = memory_region_get_ram_ptr(mr) + xlat;
> -    *read_only = !writable || mr->readonly;
> +    if (vaddr) {
> +        *vaddr = memory_region_get_ram_ptr(mr) + xlat;
> +    }
> +
> +    if (ram_addr) {
> +        *ram_addr = memory_region_get_ram_addr(mr) + xlat;
> +    }
> +
> +    if (read_only) {
> +        *read_only = !writable || mr->readonly;
> +    }
>  
>      return true;
>  }
> @@ -485,7 +494,6 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, 
> IOMMUTLBEntry *iotlb)
>      VFIOGuestIOMMU *giommu = container_of(n, VFIOGuestIOMMU, n);
>      VFIOContainer *container = giommu->container;
>      hwaddr iova = iotlb->iova + giommu->iommu_offset;
> -    bool read_only;
>      void *vaddr;
>      int ret;
>  
> @@ -501,7 +509,9 @@ static void vfio_iommu_map_notify(IOMMUNotifier *n, 
> IOMMUTLBEntry *iotlb)
>      rcu_read_lock();
>  
>      if ((iotlb->perm & IOMMU_RW) != IOMMU_NONE) {
> -        if (!vfio_get_vaddr(iotlb, &vaddr, &read_only)) {
> +        bool read_only;
> +
> +        if (!vfio_get_xlat_addr(iotlb, &vaddr, NULL, &read_only)) {
>              goto out;
>          }
>          /*
> @@ -899,11 +909,77 @@ err_out:
>      return ret;
>  }
>  
> +typedef struct {
> +    IOMMUNotifier n;
> +    VFIOGuestIOMMU *giommu;
> +} vfio_giommu_dirty_notifier;
> +
> +static void vfio_iommu_map_dirty_notify(IOMMUNotifier *n, IOMMUTLBEntry 
> *iotlb)
> +{
> +    vfio_giommu_dirty_notifier *gdn = container_of(n,
> +                                                vfio_giommu_dirty_notifier, 
> n);
> +    VFIOGuestIOMMU *giommu = gdn->giommu;
> +    VFIOContainer *container = giommu->container;
> +    hwaddr iova = iotlb->iova + giommu->iommu_offset;
> +    ram_addr_t translated_addr;
> +
> +    trace_vfio_iommu_map_dirty_notify(iova, iova + iotlb->addr_mask);
> +
> +    if (iotlb->target_as != &address_space_memory) {
> +        error_report("Wrong target AS \"%s\", only system memory is allowed",
> +                     iotlb->target_as->name ? iotlb->target_as->name : 
> "none");
> +        return;
> +    }
> +
> +    rcu_read_lock();
> +    if (vfio_get_xlat_addr(iotlb, NULL, &translated_addr, NULL)) {
> +        int ret;
> +
> +        ret = vfio_get_dirty_bitmap(container, iova, iotlb->addr_mask + 1,
> +                                    translated_addr);
> +        if (ret) {
> +            error_report("vfio_iommu_map_dirty_notify(%p, 0x%"HWADDR_PRIx", "
> +                         "0x%"HWADDR_PRIx") = %d (%m)",
> +                         container, iova,
> +                         iotlb->addr_mask + 1, ret);
> +        }
> +    }
> +    rcu_read_unlock();
> +}
> +
>  static int vfio_sync_dirty_bitmap(VFIOContainer *container,
>                                    MemoryRegionSection *section)
>  {
>      ram_addr_t ram_addr;
>  
> +    if (memory_region_is_iommu(section->mr)) {
> +        VFIOGuestIOMMU *giommu;
> +
> +        QLIST_FOREACH(giommu, &container->giommu_list, giommu_next) {
> +            if (MEMORY_REGION(giommu->iommu) == section->mr &&
> +                giommu->n.start == section->offset_within_region) {
> +                Int128 llend;
> +                vfio_giommu_dirty_notifier gdn = { .giommu = giommu };
> +                int idx = memory_region_iommu_attrs_to_index(giommu->iommu,
> +                                                       
> MEMTXATTRS_UNSPECIFIED);
> +
> +                llend = 
> int128_add(int128_make64(section->offset_within_region),
> +                                   section->size);
> +                llend = int128_sub(llend, int128_one());
> +
> +                iommu_notifier_init(&gdn.n,
> +                                    vfio_iommu_map_dirty_notify,
> +                                    IOMMU_NOTIFIER_MAP,
> +                                    section->offset_within_region,
> +                                    int128_get64(llend),
> +                                    idx);
> +                memory_region_iommu_replay(giommu->iommu, &gdn.n);
> +                break;
> +            }
> +        }
> +        return 0;
> +    }
> +
>      ram_addr = memory_region_get_ram_addr(section->mr) +
>                 section->offset_within_region;
>  
> diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events
> index dd991bd8f265..c0e75f24b76d 100644
> --- a/hw/vfio/trace-events
> +++ b/hw/vfio/trace-events
> @@ -164,3 +164,4 @@ vfio_load_state(const char *name, uint64_t data) " (%s) 
> data 0x%"PRIx64
>  vfio_load_state_device_data(const char *name, uint64_t data_offset, uint64_t 
> data_size) " (%s) Offset 0x%"PRIx64" size 0x%"PRIx64
>  vfio_load_cleanup(const char *name) " (%s)"
>  vfio_get_dirty_bitmap(int fd, uint64_t iova, uint64_t size, uint64_t 
> bitmap_size, uint64_t start) "container fd=%d, iova=0x%"PRIx64" size= 
> 0x%"PRIx64" bitmap_size=0x%"PRIx64" start=0x%"PRIx64
> +vfio_iommu_map_dirty_notify(uint64_t iova_start, uint64_t iova_end) "iommu 
> dirty @ 0x%"PRIx64" - 0x%"PRIx64
> -- 
> 2.7.0
>