Re: [PATCH v3 07/10] vfio/iommufd: Implement VFIOIOMMUClass::query_dirty_bitmap support

["Cédric Le Goater" <clg@redhat.com>]

On 7/8/24 4:34 PM, Joao Martins wrote:
> ioctl(iommufd, IOMMU_HWPT_GET_DIRTY_BITMAP, arg) is the UAPI
> that fetches the bitmap that tells what was dirty in an IOVA
> range.
> 
> A single bitmap is allocated and used across all the hwpts
> sharing an IOAS which is then used in log_sync() to set Qemu
> global bitmaps.
> 
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> ---
>   include/sysemu/iommufd.h |  3 +++
>   backends/iommufd.c       | 26 ++++++++++++++++++++++++++
>   hw/vfio/iommufd.c        | 34 ++++++++++++++++++++++++++++++++++
>   backends/trace-events    |  1 +
>   4 files changed, 64 insertions(+)
> 
> diff --git a/include/sysemu/iommufd.h b/include/sysemu/iommufd.h
> index 1470377f55ba..223f1ea14e84 100644
> --- a/include/sysemu/iommufd.h
> +++ b/include/sysemu/iommufd.h
> @@ -56,6 +56,9 @@ int iommufd_backend_alloc_hwpt(IOMMUFDBackend *be, uint32_t dev_id,
>                                  void *data_ptr, uint32_t *out_hwpt);
>   int iommufd_backend_set_dirty_tracking(IOMMUFDBackend *be, uint32_t hwpt_id,
>                                          bool start);
> +int iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, uint32_t hwpt_id,
> +                                     uint64_t iova, ram_addr_t size,
> +                                     uint64_t page_size, uint64_t *data);
>   
>   #define TYPE_HOST_IOMMU_DEVICE_IOMMUFD TYPE_HOST_IOMMU_DEVICE "-iommufd"
>   
> diff --git a/backends/iommufd.c b/backends/iommufd.c
> index 69daabc27473..b2d3bbd7c31b 100644
> --- a/backends/iommufd.c
> +++ b/backends/iommufd.c
> @@ -257,6 +257,32 @@ int iommufd_backend_set_dirty_tracking(IOMMUFDBackend *be, uint32_t hwpt_id,
>       return ret;
>   }
>   
> +int iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, uint32_t hwpt_id,
> +                                     uint64_t iova, ram_addr_t size,
> +                                     uint64_t page_size, uint64_t *data)
> +{
> +    int ret;
> +    struct iommu_hwpt_get_dirty_bitmap get_dirty_bitmap = {
> +        .size = sizeof(get_dirty_bitmap),
> +        .hwpt_id = hwpt_id,
> +        .iova = iova,
> +        .length = size,
> +        .page_size = page_size,
> +        .data = (uintptr_t)data,
> +    };
> +
> +    ret = ioctl(be->fd, IOMMU_HWPT_GET_DIRTY_BITMAP, &get_dirty_bitmap);
> +    trace_iommufd_backend_get_dirty_bitmap(be->fd, hwpt_id, iova, size,
> +                                           page_size, ret);
> +    if (ret) {
> +        error_report("IOMMU_HWPT_GET_DIRTY_BITMAP (iova: 0x%"PRIx64
> +                     " size: 0x%"PRIx64") failed: %s", iova,
> +                     size, strerror(errno));
> +    }
> +
> +    return !ret ? 0 : -errno;
> +}
> +
>   bool iommufd_backend_get_device_info(IOMMUFDBackend *be, uint32_t devid,
>                                        uint32_t *type, void *data, uint32_t len,
>                                        uint64_t *caps, Error **errp)
> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
> index 158a98cb3b12..9fad47baed9e 100644
> --- a/hw/vfio/iommufd.c
> +++ b/hw/vfio/iommufd.c
> @@ -25,6 +25,7 @@
>   #include "qemu/cutils.h"
>   #include "qemu/chardev_open.h"
>   #include "pci.h"
> +#include "exec/ram_addr.h"
>   
>   static int iommufd_cdev_map(const VFIOContainerBase *bcontainer, hwaddr iova,
>                               ram_addr_t size, void *vaddr, bool readonly)
> @@ -152,6 +153,38 @@ err:
>       return ret;
>   }
>   
> +static int iommufd_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
> +                                      VFIOBitmap *vbmap, hwaddr iova,
> +                                      hwaddr size, Error **errp)
> +{
> +    VFIOIOMMUFDContainer *container = container_of(bcontainer,
> +                                                   VFIOIOMMUFDContainer,
> +                                                   bcontainer);
> +    int ret;
> +    VFIOIOASHwpt *hwpt;
> +    unsigned long page_size;
> +
> +    page_size = qemu_real_host_page_size();
> +    QLIST_FOREACH(hwpt, &container->hwpt_list, next) {
> +        if (!iommufd_hwpt_dirty_tracking(hwpt)) {
> +            continue;
> +        }
> +
> +        ret = iommufd_backend_get_dirty_bitmap(container->be, hwpt->hwpt_id,
> +                                               iova, size, page_size,
> +                                               vbmap->bitmap);
> +        if (ret) {
> +            error_setg_errno(errp, ret,
> +                             "Failed to get dirty bitmap report, hwpt_id %u, iova: "
> +                             "0x%" HWADDR_PRIx ", size: 0x%" HWADDR_PRIx,
> +                             hwpt->hwpt_id, iova, size);

This error looks redundant with the one printed out in
iommufd_backend_get_dirty_bitmap(). Couldn't we add an 'Error **'
parameter and simply return a bool ?


Thanks,

C.



> +            return ret;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
>   static int iommufd_cdev_getfd(const char *sysfs_path, Error **errp)
>   {
>       ERRP_GUARD();
> @@ -777,6 +810,7 @@ static void vfio_iommu_iommufd_class_init(ObjectClass *klass, void *data)
>       vioc->detach_device = iommufd_cdev_detach;
>       vioc->pci_hot_reset = iommufd_cdev_pci_hot_reset;
>       vioc->set_dirty_page_tracking = iommufd_set_dirty_page_tracking;
> +    vioc->query_dirty_bitmap = iommufd_query_dirty_bitmap;
>   };
>   
>   static bool hiod_iommufd_vfio_realize(HostIOMMUDevice *hiod, void *opaque,
> diff --git a/backends/trace-events b/backends/trace-events
> index 28aca3b859d4..40811a316215 100644
> --- a/backends/trace-events
> +++ b/backends/trace-events
> @@ -17,3 +17,4 @@ iommufd_backend_alloc_ioas(int iommufd, uint32_t ioas) " iommufd=%d ioas=%d"
>   iommufd_backend_alloc_hwpt(int iommufd, uint32_t dev_id, uint32_t pt_id, uint32_t flags, uint32_t hwpt_type, uint32_t len, uint64_t data_ptr, uint32_t out_hwpt_id, int ret) " iommufd=%d dev_id=%u pt_id=%u flags=0x%x hwpt_type=%u len=%u data_ptr=0x%"PRIx64" out_hwpt=%u (%d)"
>   iommufd_backend_free_id(int iommufd, uint32_t id, int ret) " iommufd=%d id=%d (%d)"
>   iommufd_backend_set_dirty(int iommufd, uint32_t hwpt_id, bool start, int ret) " iommufd=%d hwpt=%u enable=%d (%d)"
> +iommufd_backend_get_dirty_bitmap(int iommufd, uint32_t hwpt_id, uint64_t iova, uint64_t size, uint64_t page_size, int ret) " iommufd=%d hwpt=%u iova=0x%"PRIx64" size=0x%"PRIx64" page_size=0x%"PRIx64" (%d)"