[PATCH v4 05/11] vfio: Query and store the maximum number of possible DMA mappings

[David Hildenbrand <david@redhat.com>]

Let's query the maximum number of possible DMA mappings by querying the
available mappings when creating the container (before any mappings are
created). We'll use this informaton soon to perform some sanity checks
and warn the user.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Auger Eric <eric.auger@redhat.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: teawater <teawaterz@linux.alibaba.com>
Cc: Marek Kedzierski <mkedzier@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/vfio/common.c              | 4 ++++
 include/hw/vfio/vfio-common.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 2bd219cf1d..1babb6bb99 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1934,6 +1934,7 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
     container->fd = fd;
     container->error = NULL;
     container->dirty_pages_supported = false;
+    container->dma_max_mappings = 0;
     QLIST_INIT(&container->giommu_list);
     QLIST_INIT(&container->hostwin_list);
     QLIST_INIT(&container->vrdl_list);
@@ -1965,7 +1966,10 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
         vfio_host_win_add(container, 0, (hwaddr)-1, info->iova_pgsizes);
         container->pgsizes = info->iova_pgsizes;
 
+        /* The default in the kernel ("dma_entry_limit") is 65535. */
+        container->dma_max_mappings = 65535;
         if (!ret) {
+            vfio_get_info_dma_avail(info, &container->dma_max_mappings);
             vfio_get_iommu_info_migration(container, info);
         }
         g_free(info);
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index af6f8d1b22..4b28c6e8ac 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -88,6 +88,7 @@ typedef struct VFIOContainer {
     uint64_t dirty_pgsizes;
     uint64_t max_dirty_bitmap_size;
     unsigned long pgsizes;
+    unsigned int dma_max_mappings;
     QLIST_HEAD(, VFIOGuestIOMMU) giommu_list;
     QLIST_HEAD(, VFIOHostDMAWindow) hostwin_list;
     QLIST_HEAD(, VFIOGroup) group_list;
-- 
2.29.2