Patch against 2.6.36 attached.
commit 9621afb2eb9a1f06d4afcf435175b5323a2b5cc6
Author: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Date: Mon Oct 25 11:58:22 2010 -0200
KVM: MMU: fix rmap_remove on non present sptes
commit eb45fda45f915c7ca3e81e005e853cb770da2642 upstream.
drop_spte should not attempt to rmap_remove a non present shadow pte.
This fixes a BUG_ON seen on kvm-autotest.
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Reported-by: Lucas Meneghel Rodrigues <lmr@xxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 7fed5b7..cc1bada 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -675,7 +675,7 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
}
}
-static void set_spte_track_bits(u64 *sptep, u64 new_spte)
+static int set_spte_track_bits(u64 *sptep, u64 new_spte)
{
pfn_t pfn;
u64 old_spte = *sptep;
@@ -687,18 +687,20 @@ static void set_spte_track_bits(u64 *sptep, u64 new_spte)
old_spte = __xchg_spte(sptep, new_spte);
if (!is_rmap_spte(old_spte))
- return;
+ return 0;
+
pfn = spte_to_pfn(old_spte);
if (!shadow_accessed_mask || old_spte & shadow_accessed_mask)
kvm_set_pfn_accessed(pfn);
if (is_writable_pte(old_spte))
kvm_set_pfn_dirty(pfn);
+ return 1;
}
static void drop_spte(struct kvm *kvm, u64 *sptep, u64 new_spte)
{
- set_spte_track_bits(sptep, new_spte);
- rmap_remove(kvm, sptep);
+ if (set_spte_track_bits(sptep, new_spte))
+ rmap_remove(kvm, sptep);
}
static u64 *rmap_next(struct kvm *kvm, unsigned long *rmapp, u64 *spte)
