intel_iommu: Set address mask when a translation fails and adjust W permission

Implements the behavior defined in section 10.2.3.5 of PCIe spec rev 5.
This is needed by devices that support ATS.

Signed-off-by: Clement Mathieu--Drif <clement.mathieu--drif@eviden.com>
Message-Id: <20250628180226.133285-10-clement.mathieu--drif@eviden.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index bff307b9bc..1b1b0b5632 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -2091,7 +2091,8 @@ static bool vtd_do_iommu_translate(VTDAddressSpace *vtd_as, PCIBus *bus,
     uint8_t bus_num = pci_bus_num(bus);
     VTDContextCacheEntry *cc_entry;
     uint64_t pte, page_mask;
-    uint32_t level, pasid = vtd_as->pasid;
+    uint32_t level = UINT32_MAX;
+    uint32_t pasid = vtd_as->pasid;
     uint16_t source_id = PCI_BUILD_BDF(bus_num, devfn);
     int ret_fr;
     bool is_fpd_set = false;
@@ -2250,14 +2251,19 @@ out:
     entry->iova = addr & page_mask;
     entry->translated_addr = vtd_get_pte_addr(pte, s->aw_bits) & page_mask;
     entry->addr_mask = ~page_mask;
-    entry->perm = access_flags;
+    entry->perm = (is_write ? access_flags : (access_flags & (~IOMMU_WO)));
     return true;
 
 error:
     vtd_iommu_unlock(s);
     entry->iova = 0;
     entry->translated_addr = 0;
-    entry->addr_mask = 0;
+    /*
+     * Set the mask for ATS (the range must be present even when the
+     * translation fails : PCIe rev 5 10.2.3.5)
+     */
+    entry->addr_mask = (level != UINT32_MAX) ?
+                       (~vtd_pt_level_page_mask(level)) : (~VTD_PAGE_MASK_4K);
     entry->perm = IOMMU_NONE;
     return false;
 }