From: Marcelo Tosatti <mtosatti@redhat.com>
To: kvm <kvm@vger.kernel.org>
Cc: Avi Kivity <avi@redhat.com>
Subject: KVM: MMU: only write protect mappings at pagetable level
Date: Wed, 22 Dec 2010 09:01:57 -0200 [thread overview]
Message-ID: <20101222110157.GA4266@amt.cnet> (raw)
If a pagetable contains a writeable large spte, all of its sptes will be
write protected, including non-leaf ones, leading to endless pagefaults.
Do not write protect pages above PT_PAGE_TABLE_LEVEL, as the spte fault
paths assume non-leaf sptes are writable.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index c3853d5..c716ff8 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3442,6 +3442,9 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
if (!test_bit(slot, sp->slot_bitmap))
continue;
+ if (sp->role.level != PT_PAGE_TABLE_LEVEL)
+ continue;
+
pt = sp->spt;
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
/* avoid RMW */
next reply other threads:[~2010-12-22 11:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-22 11:01 Marcelo Tosatti [this message]
2010-12-22 11:07 ` KVM: MMU: only write protect mappings at pagetable level Avi Kivity
2010-12-22 11:12 ` Marcelo Tosatti
2010-12-22 13:01 ` Avi Kivity
2010-12-22 13:06 ` Marcelo Tosatti
2010-12-22 14:06 ` Avi Kivity
2010-12-22 17:48 ` Alex Williamson
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