[Qemu-devel] [PATCH for-2.5 1/1] spapr: Handle failure of KVM_PPC_ALLOCATE_HTAB ioctl

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

KVM_PPC_ALLOCATE_HTAB ioctl can return -ENOMEM for KVM guests and QEMU
never handled this correctly. But this didn't cause any problems till
now as KVM_PPC_ALLOCATE_HTAB ioctl returned with smaller than requested
HTAB when enough contiguous memory wasn't available in the host.
After the proposed kernel change: https://patchwork.ozlabs.org/patch/530501/,
KVM_PPC_ALLOCATE_HTAB ioctl will not fallback to lower sized HTAB
allocation and will fail if requested HTAB size can't be met.

Check for such failures in QEMU and abort appropriately. This will
prevent guest kernel from hanging/freezing during early boot by doing
graceful exit when host is unable to allocate requested HTAB.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
 hw/ppc/spapr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index e1202ce..ec6e141 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1022,7 +1022,7 @@ static void spapr_alloc_htab(sPAPRMachineState *spapr)
 
     shift = kvmppc_reset_htab(spapr->htab_shift);
 
-    if (shift > 0) {
+    if (shift != 0) {
         /* Kernel handles htab, we don't need to allocate one */
         if (shift != spapr->htab_shift) {
             error_setg(&error_abort, "Failed to allocate HTAB of requested size, try with smaller maxmem");
@@ -1055,7 +1055,7 @@ static void spapr_reset_htab(sPAPRMachineState *spapr)
     int index;
 
     shift = kvmppc_reset_htab(spapr->htab_shift);
-    if (shift > 0) {
+    if (shift != 0) {
         if (shift != spapr->htab_shift) {
             error_setg(&error_abort, "Requested HTAB allocation failed during reset");
         }
-- 
2.1.0