[PATCH v2 06/20] amd_iommu: Return an error when unable to read PTE from guest memory

[Alejandro Jimenez]

Make amdvi_get_pte_entry() return an error value (-1) in cases where the
memory read fails, versus the current return of 0 to indicate failure.
The reason is that 0 is also a valid PTE value, and it is useful to know
when a PTE points to memory that is zero i.e. the guest unmapped the
page.

Signed-off-by: Alejandro Jimenez <alejandro.j.jime...@oracle.com>
---
 hw/i386/amd_iommu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
index 5322a614f5d6..698967cc1a88 100644
--- a/hw/i386/amd_iommu.c
+++ b/hw/i386/amd_iommu.c
@@ -496,7 +496,7 @@ static inline uint64_t amdvi_get_pte_entry(AMDVIState *s, 
uint64_t pte_addr,
                         &pte, sizeof(pte), MEMTXATTRS_UNSPECIFIED)) {
         trace_amdvi_get_pte_hwerror(pte_addr);
         amdvi_log_pagetab_error(s, devid, pte_addr, 0);
-        pte = 0;
+        pte = (uint64_t)-1;
         return pte;
     }
 
@@ -1024,7 +1024,7 @@ static void amdvi_page_walk(AMDVIAddressSpace *as, 
uint64_t *dte,
             /* add offset and load pte */
             pte_addr += ((addr >> (3 + 9 * level)) & 0x1FF) << 3;
             pte = amdvi_get_pte_entry(as->iommu_state, pte_addr, as->devfn);
-            if (!pte) {
+            if (!pte || (pte == (uint64_t)-1)) {
                 return;
             }
             oldlevel = level;
-- 
2.43.5