[PATCH ats_vtd 03/22] intel_iommu: return page walk level even when the translation fails

[CLEMENT MATHIEU--DRIF]

We use this information in vtd_do_iommu_translate to populate the
IOMMUTLBEntry and indicate the correct page mask. This prevents ATS
devices from sending many useless translation requests when a megapage
or gigapage iova is not mapped to a physical address.

Signed-off-by: Clément Mathieu--Drif <clement.mathieu--d...@eviden.com>
---
 hw/i386/intel_iommu.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index fc8890f4e6..a2b275016c 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -2078,9 +2078,9 @@ static int vtd_iova_to_flpte(IntelIOMMUState *s, 
VTDContextEntry *ce,
                              uint32_t pasid)
 {
     dma_addr_t addr = vtd_get_iova_pgtbl_base(s, ce, pasid);
-    uint32_t level = vtd_get_iova_level(s, ce, pasid);
     uint32_t offset;
     uint64_t flpte;
+    *flpte_level = vtd_get_iova_level(s, ce, pasid);
 
     if (!vtd_iova_fl_check_canonical(s, iova, ce, pasid)) {
         error_report_once("%s: detected non canonical IOVA (iova=0x%" PRIx64 
","
@@ -2089,10 +2089,10 @@ static int vtd_iova_to_flpte(IntelIOMMUState *s, 
VTDContextEntry *ce,
     }
 
     while (true) {
-        offset = vtd_iova_fl_level_offset(iova, level);
+        offset = vtd_iova_fl_level_offset(iova, *flpte_level);
         flpte = vtd_get_flpte(addr, offset);
         if (flpte == (uint64_t)-1) {
-            if (level == vtd_get_iova_level(s, ce, pasid)) {
+            if (*flpte_level == vtd_get_iova_level(s, ce, pasid)) {
                 /* Invalid programming of context-entry */
                 return -VTD_FR_CONTEXT_ENTRY_INV;
             } else {
@@ -2117,19 +2117,18 @@ static int vtd_iova_to_flpte(IntelIOMMUState *s, 
VTDContextEntry *ce,
             return -VTD_FR_FS_BIT_UPDATE_FAILED;
         }
 
-        if (vtd_is_last_flpte(flpte, level)) {
+        if (vtd_is_last_flpte(flpte, *flpte_level)) {
             if (is_write &&
                 (vtd_set_flag_in_pte(addr, offset, flpte, VTD_FL_PTE_D) !=
                                                                     MEMTX_OK)) 
{
                     return -VTD_FR_FS_BIT_UPDATE_FAILED;
             }
             *flptep = flpte;
-            *flpte_level = level;
             return 0;
         }
 
         addr = vtd_get_flpte_addr(flpte, aw_bits);
-        level--;
+        (*flpte_level)--;
     }
 }
 
-- 
2.44.0