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Commit eb45fda4 authored by Marcelo Tosatti's avatar Marcelo Tosatti
Browse files

KVM: MMU: fix rmap_remove on non present sptes 



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: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Reported-by: default avatarLucas Meneghel Rodrigues <lmr@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent edde99ce

arch/x86/kvm/mmu.c

+5 −4
Original line number Diff line number Diff line
@@ -720,7 +720,7 @@ 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;
@@ -731,18 +731,19 @@ 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 (!shadow_dirty_mask || (old_spte & shadow_dirty_mask))

		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);

	if (set_spte_track_bits(sptep, new_spte))

		rmap_remove(kvm, sptep);

}