We already have vtd_find_add_as() to find an AS from BDF+pasid, but this
pasid is passed from PCI subsystem. PCI device supports two request types,
Requests-without-PASID and Requests-with-PASID. Requests-without-PASID
doesn't include a PASID TLP prefix, IOMMU fetches rid_pasid from context
entry and use it as IOMMU's pasid to index pasid table.

So we need to translate between PCI's pasid and IOMMU's pasid specially
for Requests-without-PASID, e.g., PCI_NO_PASID(-1) <-> rid_pasid.
For Requests-with-PASID, PCI's pasid and IOMMU's pasid are same value.

vtd_as_from_iommu_pasid_locked() translates from BDF+iommu_pasid to vtd_as
which contains PCI's pasid vtd_as->pasid.

vtd_as_to_iommu_pasid_locked() translates from BDF+vtd_as->pasid to iommu_pasid.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
---
 hw/i386/intel_iommu.c | 50 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index b2ea109c7c..a9c0bd5021 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -1617,6 +1617,56 @@ static int vtd_as_to_context_entry(VTDAddressSpace *vtd_as, VTDContextEntry *ce)
     }
 }
 
+static inline int vtd_as_to_iommu_pasid_locked(VTDAddressSpace *vtd_as,
+                                               uint32_t *pasid)
+{
+    VTDContextEntry ce;
+    int ret;
+
+    ret = vtd_as_to_context_entry(vtd_as, &ce);
+    if (ret) {
+        return ret;
+    }
+
+    /* Translate to iommu pasid if PCI_NO_PASID */
+    if (vtd_as->pasid == PCI_NO_PASID) {
+        *pasid = VTD_CE_GET_RID2PASID(&ce);
+    } else {
+        *pasid = vtd_as->pasid;
+    }
+
+    return 0;
+}
+
+static gboolean vtd_find_as_by_sid_and_iommu_pasid(gpointer key, gpointer value,
+                                                   gpointer user_data)
+{
+    VTDAddressSpace *vtd_as = (VTDAddressSpace *)value;
+    struct vtd_as_raw_key *target = (struct vtd_as_raw_key *)user_data;
+    uint16_t sid = PCI_BUILD_BDF(pci_bus_num(vtd_as->bus), vtd_as->devfn);
+    uint32_t pasid;
+
+    if (vtd_as_to_iommu_pasid_locked(vtd_as, &pasid)) {
+        return false;
+    }
+
+    return (pasid == target->pasid) && (sid == target->sid);
+}
+
+/* Translate iommu pasid to vtd_as */
+static inline
+VTDAddressSpace *vtd_as_from_iommu_pasid_locked(IntelIOMMUState *s,
+                                                uint16_t sid, uint32_t pasid)
+{
+    struct vtd_as_raw_key key = {
+        .sid = sid,
+        .pasid = pasid
+    };
+
+    return g_hash_table_find(s->vtd_address_spaces,
+                             vtd_find_as_by_sid_and_iommu_pasid, &key);
+}
+
 static int vtd_sync_shadow_page_hook(const IOMMUTLBEvent *event,
                                      void *private)
 {
-- 
2.34.1