[Qemu-devel] [PATCH V2 3/3] spapr: Fix stale HTAB during live migration (TCG)

[Samuel Mendoza-Jonas]

If a TCG guest reboots during a running migration HTAB entries are not
marked dirty, and the destination boots with an invalid HTAB.

When a reboot occurs, explicitly mark the current HTAB dirty after
clearing it.

Signed-off-by: Samuel Mendoza-Jonas <address@hidden>
---
 hw/ppc/spapr.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 10b7b00..c2efbcd 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -819,9 +819,16 @@ static void emulate_spapr_hypercall(PowerPCCPU *cpu)
     }
 }
 
+#define HPTE(_table, _i)   (void *)(((uint64_t *)(_table)) + ((_i) * 2))
+#define HPTE_VALID(_hpte)  (tswap64(*((uint64_t *)(_hpte))) & HPTE64_V_VALID)
+#define HPTE_DIRTY(_hpte)  (tswap64(*((uint64_t *)(_hpte))) & 
HPTE64_V_HPTE_DIRTY)
+#define CLEAN_HPTE(_hpte)  ((*(uint64_t *)(_hpte)) &= 
tswap64(~HPTE64_V_HPTE_DIRTY))
+#define DIRTY_HPTE(_hpte)  ((*(uint64_t *)(_hpte)) |= 
tswap64(HPTE64_V_HPTE_DIRTY))
+
 static void spapr_reset_htab(sPAPREnvironment *spapr)
 {
     long shift;
+    int index;
 
     /* allocate hash page table.  For now we always make this 16mb,
      * later we should probably make it scale to the size of guest
@@ -846,6 +853,10 @@ static void spapr_reset_htab(sPAPREnvironment *spapr)
 
         /* And clear it */
         memset(spapr->htab, 0, HTAB_SIZE(spapr));
+
+        for (index = 0; index < HTAB_SIZE(spapr) / HASH_PTE_SIZE_64; index++) {
+            DIRTY_HPTE(HPTE(spapr->htab, index));
+        }
     }
 
     /* Update the RMA size if necessary */
@@ -993,11 +1004,6 @@ static const VMStateDescription vmstate_spapr = {
     },
 };
 
-#define HPTE(_table, _i)   (void *)(((uint64_t *)(_table)) + ((_i) * 2))
-#define HPTE_VALID(_hpte)  (tswap64(*((uint64_t *)(_hpte))) & HPTE64_V_VALID)
-#define HPTE_DIRTY(_hpte)  (tswap64(*((uint64_t *)(_hpte))) & 
HPTE64_V_HPTE_DIRTY)
-#define CLEAN_HPTE(_hpte)  ((*(uint64_t *)(_hpte)) &= 
tswap64(~HPTE64_V_HPTE_DIRTY))
-
 static int htab_save_setup(QEMUFile *f, void *opaque)
 {
     sPAPREnvironment *spapr = opaque;
-- 
1.9.3