[PATCH v1 09/22] vfio/common: check PASID alloc/free availability

[Liu Yi L]

VFIO exposes host IOMMU dual-stage DMA translation programming capability
to userspace by VFIO_TYPE1_NESTING_IOMMU type. However, userspace needs
more info on the nesting type. e.g. the supported stage 1 format and PASID
alloc/free request availability.

This patch gets the iommu nesting cap info from kernel by using IOCTL
VFIO_IOMMU_GET_INFO. And checks the HOST_IOMMU_PASID_REQUEST bit in the
nesting capabilities.

This patch referred some code from Shameer Kolothum.
https://lists.gnu.org/archive/html/qemu-devel/2018-05/msg03759.html

Cc: Kevin Tian <address@hidden>
Cc: Jacob Pan <address@hidden>
Cc: Peter Xu <address@hidden>
Cc: Eric Auger <address@hidden>
Cc: Yi Sun <address@hidden>
Cc: David Gibson <address@hidden>
Cc: Alex Williamson <address@hidden>
Signed-off-by: Shameer Kolothum <address@hidden>
Signed-off-by: Liu Yi L <address@hidden>
---
 hw/vfio/common.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 91 insertions(+), 5 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index e4f5f10..e0f2828 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -1223,6 +1223,84 @@ static int vfio_host_icx_pasid_free(HostIOMMUContext 
*host_icx,
     return 0;
 }
 
+/**
+ * Get iommu info from host. Caller of this funcion should free
+ * the memory pointed by the returned pointer stored in @info
+ * after a successful calling when finished its usage.
+ */
+static int vfio_get_iommu_info(VFIOContainer *container,
+                         struct vfio_iommu_type1_info **info)
+{
+
+    size_t argsz = sizeof(struct vfio_iommu_type1_info);
+
+    *info = g_malloc0(argsz);
+
+retry:
+    (*info)->argsz = argsz;
+
+    if (ioctl(container->fd, VFIO_IOMMU_GET_INFO, *info)) {
+        g_free(*info);
+        *info = NULL;
+        return -errno;
+    }
+
+    if (((*info)->argsz > argsz)) {
+        argsz = (*info)->argsz;
+        *info = g_realloc(*info, argsz);
+        goto retry;
+    }
+
+    return 0;
+}
+
+static struct vfio_info_cap_header *
+vfio_get_iommu_info_cap(struct vfio_iommu_type1_info *info, uint16_t id)
+{
+    struct vfio_info_cap_header *hdr;
+    void *ptr = info;
+
+    if (!(info->flags & VFIO_IOMMU_INFO_CAPS)) {
+        return NULL;
+    }
+
+    for (hdr = ptr + info->cap_offset; hdr != ptr; hdr = ptr + hdr->next) {
+        if (hdr->id == id) {
+            return hdr;
+        }
+    }
+
+    return NULL;
+}
+
+static int vfio_get_nesting_iommu_cap(VFIOContainer *container,
+                   struct vfio_iommu_type1_info_cap_nesting *cap_nesting)
+{
+    struct vfio_iommu_type1_info *info;
+    struct vfio_info_cap_header *hdr;
+    struct vfio_iommu_type1_info_cap_nesting *cap;
+    int ret;
+
+    ret = vfio_get_iommu_info(container, &info);
+    if (ret) {
+        return ret;
+    }
+
+    hdr = vfio_get_iommu_info_cap(info,
+                        VFIO_IOMMU_TYPE1_INFO_CAP_NESTING);
+    if (!hdr) {
+        g_free(info);
+        return -errno;
+    }
+
+    cap = container_of(hdr,
+                struct vfio_iommu_type1_info_cap_nesting, header);
+    *cap_nesting = *cap;
+
+    g_free(info);
+    return 0;
+}
+
 static int vfio_init_container(VFIOContainer *container, int group_fd,
                                Error **errp)
 {
@@ -1256,11 +1334,19 @@ static int vfio_init_container(VFIOContainer 
*container, int group_fd,
     }
 
     if (iommu_type == VFIO_TYPE1_NESTING_IOMMU) {
-        /*
-         * TODO: config flags per host IOMMU nesting capability
-         * e.g. check if VFIO_TYPE1_NESTING_IOMMU supports PASID
-         * alloc/free
-         */
+        struct vfio_iommu_type1_info_cap_nesting nesting = {
+                                         .nesting_capabilities = 0x0,
+                                         .stage1_formats = 0, };
+
+        ret = vfio_get_nesting_iommu_cap(container, &nesting);
+        if (ret) {
+            error_setg_errno(errp, -ret,
+                             "Failed to get nesting iommu cap");
+            return ret;
+        }
+
+        flags |= (nesting.nesting_capabilities & VFIO_IOMMU_PASID_REQS) ?
+                 HOST_IOMMU_PASID_REQUEST : 0;
         host_iommu_ctx_init(&container->host_icx,
                             sizeof(container->host_icx),
                             TYPE_VFIO_HOST_IOMMU_CONTEXT,
-- 
2.7.4