virtio-iommu : Retrieve page size mask on virtio_iommu_set_iommu_device()

Retrieve the Host IOMMU Device page size mask when this latter is set.
This allows to get the information much sooner than when relying on
IOMMU MR set_page_size_mask() call, whcih happens when the IOMMU MR
gets enabled. We introduce check_page_size_mask() helper whose code
is inherited from current virtio_iommu_set_page_size_mask()
implementation. This callback will be removed in a subsequent patch.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/trace-events

@@ -132,6 +132,7 @@ virtio_iommu_notify_map(const char *name, uint64_t virt_start, uint64_t virt_end
 virtio_iommu_notify_unmap(const char *name, uint64_t virt_start, uint64_t virt_end) "mr=%s virt_start=0x%"PRIx64" virt_end=0x%"PRIx64
 virtio_iommu_remap(const char *name, uint64_t virt_start, uint64_t virt_end, uint64_t phys_start) "mr=%s virt_start=0x%"PRIx64" virt_end=0x%"PRIx64" phys_start=0x%"PRIx64
 virtio_iommu_set_page_size_mask(const char *name, uint64_t old, uint64_t new) "mr=%s old_mask=0x%"PRIx64" new_mask=0x%"PRIx64
+virtio_iommu_update_page_size_mask(const char *name, uint64_t old, uint64_t new) "host iommu device=%s old_mask=0x%"PRIx64" new_mask=0x%"PRIx64
 virtio_iommu_notify_flag_add(const char *name) "add notifier to mr %s"
 virtio_iommu_notify_flag_del(const char *name) "del notifier from mr %s"
 virtio_iommu_switch_address_space(uint8_t bus, uint8_t slot, uint8_t fn, bool on) "Device %02x:%02x.%x switching address space (iommu enabled=%d)"

hw/virtio/virtio-iommu.c

@@ -618,9 +618,39 @@ out:
     return ret;
 }
 
+static bool check_page_size_mask(VirtIOIOMMU *viommu, uint64_t new_mask,
+                                 Error **errp)
+{
+    uint64_t cur_mask = viommu->config.page_size_mask;
+
+    if ((cur_mask & new_mask) == 0) {
+        error_setg(errp, "virtio-iommu reports a page size mask 0x%"PRIx64
+                   " incompatible with currently supported mask 0x%"PRIx64,
+                   new_mask, cur_mask);
+        return false;
+    }
+    /*
+     * Once the granule is frozen we can't change the mask anymore. If by
+     * chance the hotplugged device supports the same granule, we can still
+     * accept it.
+     */
+    if (viommu->granule_frozen) {
+        int cur_granule = ctz64(cur_mask);
+
+        if (!(BIT_ULL(cur_granule) & new_mask)) {
+            error_setg(errp,
+                       "virtio-iommu does not support frozen granule 0x%llx",
+                       BIT_ULL(cur_granule));
+            return false;
+        }
+    }
+    return true;
+}
+
 static bool virtio_iommu_set_iommu_device(PCIBus *bus, void *opaque, int devfn,
                                           HostIOMMUDevice *hiod, Error **errp)
 {
+    ERRP_GUARD();
     VirtIOIOMMU *viommu = opaque;
     HostIOMMUDeviceClass *hiodc = HOST_IOMMU_DEVICE_GET_CLASS(hiod);
     struct hiod_key *new_key;
@@ -643,8 +673,28 @@ static bool virtio_iommu_set_iommu_device(PCIBus *bus, void *opaque, int devfn,
                                                 hiod->aliased_devfn,
                                                 host_iova_ranges, errp);
         if (ret) {
-            g_list_free_full(host_iova_ranges, g_free);
-            return false;
+            goto error;
+        }
+    }
+    if (hiodc->get_page_size_mask) {
+        uint64_t new_mask = hiodc->get_page_size_mask(hiod);
+
+        if (check_page_size_mask(viommu, new_mask, errp)) {
+            /*
+             * The default mask depends on the "granule" property. For example,
+             * with 4k granule, it is -(4 * KiB). When an assigned device has
+             * page size restrictions due to the hardware IOMMU configuration,
+             * apply this restriction to the mask.
+             */
+            trace_virtio_iommu_update_page_size_mask(hiod->name,
+                                                     viommu->config.page_size_mask,
+                                                     new_mask);
+            if (!viommu->granule_frozen) {
+                viommu->config.page_size_mask &= new_mask;
+            }
+        } else {
+            error_prepend(errp, "%s: ", hiod->name);
+            goto error;
         }
     }
 
@@ -657,6 +707,9 @@ static bool virtio_iommu_set_iommu_device(PCIBus *bus, void *opaque, int devfn,
     g_list_free_full(host_iova_ranges, g_free);
 
     return true;
+error:
+    g_list_free_full(host_iova_ranges, g_free);
+    return false;
 }
 
 static void