Commit e49146dc authored Dec 22, 2010 by Marcelo Tosatti Committed by Avi Kivity Jan 12, 2011

KVM: MMU: only write protect mappings at pagetable level



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.

Tested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

parent 16d8f72f

arch/x86/kvm/mmu.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -3445,6 +3445,9 @@ 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 */

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