Re: [PATCH RFCv2 5/8] vfio/iommufd: Implement VFIOIOMMUClass::query_dirty_bitmap support

[Avihai Horon]

Hi Joao,

On 12/02/2024 15:56, Joao Martins wrote:
> External email: Use caution opening links or attachments
>
>
> 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>
> ---
>   backends/iommufd.c       | 24 ++++++++++++++++++++++++
>   backends/trace-events    |  1 +
>   hw/vfio/iommufd.c        | 30 ++++++++++++++++++++++++++++++
>   include/sysemu/iommufd.h |  3 +++
>   4 files changed, 58 insertions(+)
>
> diff --git a/backends/iommufd.c b/backends/iommufd.c
> index 954de61c2da0..dd676d493c37 100644
> --- a/backends/iommufd.c
> +++ b/backends/iommufd.c
> @@ -259,6 +259,30 @@ int iommufd_backend_set_dirty_tracking(IOMMUFDBackend *be, 
> uint32_t hwpt_id,
>       return !ret ? 0 : -errno;
>   }
>
> +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,

Member per line for readability?

> +    };
> +
> +    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;
> +}
> +
>   static const TypeInfo iommufd_backend_info = {
>       .name = TYPE_IOMMUFD_BACKEND,
>       .parent = TYPE_OBJECT,
> diff --git a/backends/trace-events b/backends/trace-events
> index feba2baca5f7..11a27cb114b6 100644
> --- a/backends/trace-events
> +++ b/backends/trace-events
> @@ -17,3 +17,4 @@ iommufd_backend_alloc_hwpt(int iommufd, uint32_t dev_id, 
> uint32_t pt_id, uint32_
>   iommufd_backend_alloc_ioas(int iommufd, uint32_t ioas, int ret) " iommufd=%d 
> ioas=%d (%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=%d 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=%d iova=0x%"PRIx64" size=0x%"PRIx64" page_size=0x%"PRIx64" 
> (%d)"

s/hwpt=%d/hwpt=%u

> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
> index 361e659288fd..79b13bd262cc 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"
>   #include "migration/migration.h"
>
>   static int iommufd_cdev_map(const VFIOContainerBase *bcontainer, hwaddr iova,
> @@ -142,6 +143,34 @@ err:
>       return ret;
>   }
>
> +static int iommufd_query_dirty_bitmap(const VFIOContainerBase *bcontainer,
> +                                      VFIOBitmap *vbmap, uint64_t iova,
> +                                      uint64_t size)
> +{
> +    VFIOIOMMUFDContainer *container = container_of(bcontainer,
> +                                                   VFIOIOMMUFDContainer,
> +                                                   bcontainer);
> +    int ret;
> +    VFIOIOASHwpt *hwpt;
> +    unsigned long page_size;
> +
> +    if (!bcontainer->dirty_pages_supported) {

Do we need this check?
IIUC, if we got to iommufd_query_dirty_bitmap(), it means 
bcontainer->dirty_pages_supported is already true.

Thanks.

> +        return 0;
> +    }
> +
> +    page_size = qemu_real_host_page_size();
> +    QLIST_FOREACH(hwpt, &container->hwpt_list, next) {
> +        ret = iommufd_backend_get_dirty_bitmap(container->be, hwpt->hwpt_id,
> +                                               iova, size, page_size,
> +                                               vbmap->bitmap);
> +        if (ret) {
> +            break;
> +        }
> +    }
> +
> +    return ret;
> +}
> +
>   static int iommufd_cdev_getfd(const char *sysfs_path, Error **errp)
>   {
>       long int ret = -ENOTTY;
> @@ -765,6 +794,7 @@ static void vfio_iommu_iommufd_class_init(ObjectClass 
> *klass, void *data)
>       vioc->pci_hot_reset = iommufd_cdev_pci_hot_reset;
>       vioc->host_iommu_device_init = vfio_cdev_host_iommu_device_init;
>       vioc->set_dirty_page_tracking = iommufd_set_dirty_page_tracking;
> +    vioc->query_dirty_bitmap = iommufd_query_dirty_bitmap;
>   };
>
>   static const TypeInfo types[] = {
> diff --git a/include/sysemu/iommufd.h b/include/sysemu/iommufd.h
> index 562c189dd92c..ba19b7ea4c19 100644
> --- a/include/sysemu/iommufd.h
> +++ b/include/sysemu/iommufd.h
> @@ -55,5 +55,8 @@ int iommufd_backend_alloc_hwpt(int iommufd, 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);
>
>   #endif
> --
> 2.39.3