When guest deletes PASID entries, QEMU will capture the pasid cache
invalidation request, walk through pasid_cache_list in each passthrough
device to find stale VTDACCELPASIDCacheEntry and delete them.

This happen before the PASID entry addition, because a new added entry
should never be removed.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
---
 hw/i386/intel_iommu_accel.c | 70 +++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/hw/i386/intel_iommu_accel.c b/hw/i386/intel_iommu_accel.c
index 57286f443e..2c17365a27 100644
--- a/hw/i386/intel_iommu_accel.c
+++ b/hw/i386/intel_iommu_accel.c
@@ -16,6 +16,28 @@
 #include "hw/pci/pci_bus.h"
 #include "trace.h"
 
+static inline int vtd_hiod_get_pe_from_pasid(VTDACCELPASIDCacheEntry *vtd_pce,
+                                             VTDPASIDEntry *pe)
+{
+    VTDHostIOMMUDevice *vtd_hiod = vtd_pce->vtd_hiod;
+    IntelIOMMUState *s = vtd_hiod->iommu_state;
+    uint32_t pasid = vtd_pce->pasid;
+    VTDContextEntry ce;
+    int ret;
+
+    if (!s->dmar_enabled || !s->root_scalable) {
+        return -VTD_FR_RTADDR_INV_TTM;
+    }
+
+    ret = vtd_dev_to_context_entry(s, pci_bus_num(vtd_hiod->bus),
+                                   vtd_hiod->devfn, &ce);
+    if (ret) {
+        return ret;
+    }
+
+    return vtd_ce_get_pasid_entry(s, &ce, pe, pasid);
+}
+
 bool vtd_check_hiod_accel(IntelIOMMUState *s, VTDHostIOMMUDevice *vtd_hiod,
                           Error **errp)
 {
@@ -253,6 +275,52 @@ void vtd_flush_host_piotlb_all_locked(IntelIOMMUState *s, uint16_t domain_id,
                          vtd_flush_host_piotlb_locked, &piotlb_info);
 }
 
+static void vtd_pasid_cache_invalidate_one(VTDACCELPASIDCacheEntry *vtd_pce,
+                                           VTDPASIDCacheInfo *pc_info)
+{
+    VTDPASIDEntry pe;
+    uint16_t did;
+
+    /*
+     * VTD_INV_DESC_PASIDC_G_DSI and VTD_INV_DESC_PASIDC_G_PASID_SI require
+     * DID check. If DID doesn't match the value in cache or memory, then
+     * it's not a pasid entry we want to invalidate.
+     */
+    switch (pc_info->type) {
+    case VTD_INV_DESC_PASIDC_G_PASID_SI:
+        if (pc_info->pasid != vtd_pce->pasid) {
+            return;
+        }
+        /* Fall through */
+    case VTD_INV_DESC_PASIDC_G_DSI:
+        did = VTD_SM_PASID_ENTRY_DID(&vtd_pce->pe);
+        if (pc_info->did != did) {
+            return;
+        }
+    }
+
+    if (vtd_hiod_get_pe_from_pasid(vtd_pce, &pe)) {
+        /*
+         * No valid pasid entry in guest memory. e.g. pasid entry was modified
+         * to be either all-zero or non-present. Either case means existing
+         * pasid cache should be invalidated.
+         */
+        QLIST_REMOVE(vtd_pce, next);
+        g_free(vtd_pce);
+    }
+}
+
+/* Delete invalid pasid cache entry from pasid_cache_list */
+static void vtd_pasid_cache_invalidate(VTDHostIOMMUDevice *vtd_hiod,
+                                       VTDPASIDCacheInfo *pc_info)
+{
+    VTDACCELPASIDCacheEntry *vtd_pce, *next;
+
+    QLIST_FOREACH_SAFE(vtd_pce, &vtd_hiod->pasid_cache_list, next, next) {
+        vtd_pasid_cache_invalidate_one(vtd_pce, pc_info);
+    }
+}
+
 static void vtd_find_add_pc(VTDHostIOMMUDevice *vtd_hiod, uint32_t pasid,
                             VTDPASIDEntry *pe)
 {
@@ -419,6 +487,8 @@ void vtd_pasid_cache_sync_accel(IntelIOMMUState *s, VTDPASIDCacheInfo *pc_info)
                                  TYPE_HOST_IOMMU_DEVICE_IOMMUFD)) {
             continue;
         }
+
+        vtd_pasid_cache_invalidate(vtd_hiod, pc_info);
         vtd_replay_pasid_bind_for_dev(vtd_hiod, start, end, pc_info);
     }
 }
-- 
2.47.3