Re: [Qemu-devel] [PATCH qemu v16 16/19] vfio: Add host side DMA window capabilities

[Alex Williamson]

On Wed,  4 May 2016 16:52:28 +1000
Alexey Kardashevskiy <address@hidden> wrote:

> There are going to be multiple IOMMUs per a container. This moves
> the single host IOMMU parameter set to a list of VFIOHostDMAWindow.
> 
> This should cause no behavioral change and will be used later by
> the SPAPR TCE IOMMU v2 which will also add a vfio_host_win_del() helper.
> 
> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> Reviewed-by: David Gibson <address@hidden>
> ---
> Changes:
> v16:
> * adjusted commit log with changes from v15
> 
> v15:
> * s/vfio_host_iommu_add/vfio_host_win_add/
> * s/VFIOHostIOMMU/VFIOHostDMAWindow/
> ---
>  hw/vfio/common.c              | 65 
> +++++++++++++++++++++++++++++++++----------
>  include/hw/vfio/vfio-common.h |  9 ++++--
>  2 files changed, 57 insertions(+), 17 deletions(-)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 496eb82..3f2fb23 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -29,6 +29,7 @@
>  #include "exec/memory.h"
>  #include "hw/hw.h"
>  #include "qemu/error-report.h"
> +#include "qemu/range.h"
>  #include "sysemu/kvm.h"
>  #include "trace.h"
>  
> @@ -239,6 +240,45 @@ static int vfio_dma_map(VFIOContainer *container, hwaddr 
> iova,
>      return -errno;
>  }
>  
> +static VFIOHostDMAWindow *vfio_host_win_lookup(VFIOContainer *container,
> +                                               hwaddr min_iova, hwaddr 
> max_iova)
> +{
> +    VFIOHostDMAWindow *hostwin;
> +
> +    QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) {
> +        if (hostwin->min_iova <= min_iova && max_iova <= hostwin->max_iova) {
> +            return hostwin;
> +        }
> +    }
> +
> +    return NULL;
> +}
> +
> +static int vfio_host_win_add(VFIOContainer *container,
> +                             hwaddr min_iova, hwaddr max_iova,
> +                             uint64_t iova_pgsizes)
> +{
> +    VFIOHostDMAWindow *hostwin;
> +
> +    QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) {
> +        if (ranges_overlap(min_iova, max_iova - min_iova + 1,
> +                           hostwin->min_iova,
> +                           hostwin->max_iova - hostwin->min_iova + 1)) {

Why does vfio_host_win_lookup() not also use ranges_overlap()?  In
fact, why don't we call vfio_host_win_lookup here to find the conflict?

> +            error_report("%s: Overlapped IOMMU are not enabled", __func__);
> +            return -1;

Nobody here tests the return value, shouldn't this be fatal?

> +        }
> +    }
> +
> +    hostwin = g_malloc0(sizeof(*hostwin));
> +
> +    hostwin->min_iova = min_iova;
> +    hostwin->max_iova = max_iova;
> +    hostwin->iova_pgsizes = iova_pgsizes;
> +    QLIST_INSERT_HEAD(&container->hostwin_list, hostwin, hostwin_next);
> +
> +    return 0;
> +}
> +
>  static bool vfio_listener_skipped_section(MemoryRegionSection *section)
>  {
>      return (!memory_region_is_ram(section->mr) &&
> @@ -352,7 +392,7 @@ static void vfio_listener_region_add(MemoryListener 
> *listener,
>      }
>      end = int128_get64(int128_sub(llend, int128_one()));
>  
> -    if ((iova < container->min_iova) || (end > container->max_iova)) {
> +    if (!vfio_host_win_lookup(container, iova, end)) {
>          error_report("vfio: IOMMU container %p can't map guest IOVA region"
>                       " 0x%"HWADDR_PRIx"..0x%"HWADDR_PRIx,
>                       container, iova, end);
> @@ -367,10 +407,6 @@ static void vfio_listener_region_add(MemoryListener 
> *listener,
>  
>          trace_vfio_listener_region_add_iommu(iova, end);
>          /*
> -         * FIXME: We should do some checking to see if the
> -         * capabilities of the host VFIO IOMMU are adequate to model
> -         * the guest IOMMU
> -         *
>           * FIXME: For VFIO iommu types which have KVM acceleration to
>           * avoid bouncing all map/unmaps through qemu this way, this
>           * would be the right place to wire that up (tell the KVM
> @@ -826,16 +862,14 @@ static int vfio_connect_container(VFIOGroup *group, 
> AddressSpace *as)
>           * existing Type1 IOMMUs generally support any IOVA we're
>           * going to actually try in practice.
>           */
> -        container->min_iova = 0;
> -        container->max_iova = (hwaddr)-1;
> -
> -        /* Assume just 4K IOVA page size */
> -        container->iova_pgsizes = 0x1000;
>          info.argsz = sizeof(info);
>          ret = ioctl(fd, VFIO_IOMMU_GET_INFO, &info);
>          /* Ignore errors */
>          if ((ret == 0) && (info.flags & VFIO_IOMMU_INFO_PGSIZES)) {

if (ret || !(info.flags && VFIO_IOMMU_INFO_PGSIZES)) {
    /* Assume 4k IOVA page size */
    info.iova_pgsizes = 4096;
}

vfio_host_win_add(container, 0, (hwaddr)-1, info.iova_pgsizes);

> -            container->iova_pgsizes = info.iova_pgsizes;
> +            vfio_host_win_add(container, 0, (hwaddr)-1, info.iova_pgsizes);
> +        } else {
> +            /* Assume just 4K IOVA page size */
> +            vfio_host_win_add(container, 0, (hwaddr)-1, 0x1000);
>          }
>      } else if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_IOMMU) ||
>                 ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_v2_IOMMU)) {
> @@ -892,11 +926,12 @@ static int vfio_connect_container(VFIOGroup *group, 
> AddressSpace *as)
>              ret = -errno;
>              goto listener_release_exit;
>          }
> -        container->min_iova = info.dma32_window_start;
> -        container->max_iova = container->min_iova + info.dma32_window_size - 
> 1;
>  
> -        /* Assume just 4K IOVA pages for now */
> -        container->iova_pgsizes = 0x1000;
> +        /* The default table uses 4K pages */
> +        vfio_host_win_add(container, info.dma32_window_start,
> +                          info.dma32_window_start +
> +                          info.dma32_window_size - 1,
> +                          0x1000);
>      } else {
>          error_report("vfio: No available IOMMU models");
>          ret = -EINVAL;
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index c72e45a..808263b 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -82,9 +82,8 @@ typedef struct VFIOContainer {
>       * contiguous IOVA window.  We may need to generalize that in
>       * future
>       */
> -    hwaddr min_iova, max_iova;
> -    uint64_t iova_pgsizes;
>      QLIST_HEAD(, VFIOGuestIOMMU) giommu_list;
> +    QLIST_HEAD(, VFIOHostDMAWindow) hostwin_list;
>      QLIST_HEAD(, VFIOGroup) group_list;
>      QLIST_ENTRY(VFIOContainer) next;
>  } VFIOContainer;
> @@ -97,6 +96,12 @@ typedef struct VFIOGuestIOMMU {
>      QLIST_ENTRY(VFIOGuestIOMMU) giommu_next;
>  } VFIOGuestIOMMU;
>  
> +typedef struct VFIOHostDMAWindow {
> +    hwaddr min_iova, max_iova;
> +    uint64_t iova_pgsizes;
> +    QLIST_ENTRY(VFIOHostDMAWindow) hostwin_next;
> +} VFIOHostDMAWindow;
> +
>  typedef struct VFIODeviceOps VFIODeviceOps;
>  
>  typedef struct VFIODevice {