Commit 7fa2a347 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Return old SPTE from mmu_spte_clear_track_bits() 



Return the old SPTE when clearing a SPTE and push the "old SPTE present"
check to the caller.  Private shadow page support will use the old SPTE
in rmap_remove() to determine whether or not there is a linked private
shadow page.

Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarIsaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <b16bac1fd1357aaf39e425aab2177d3f89ee8318.1625186503.git.isaku.yamahata@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 03fffc54

arch/x86/kvm/mmu/mmu.c

+7 −5
Original line number Diff line number Diff line
@@ -592,9 +592,9 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte) 
 * Rules for using mmu_spte_clear_track_bits:

 * It sets the sptep from present to nonpresent, and track the

 * state bits, it is used to clear the last level sptep.

 * Returns non-zero if the PTE was previously valid.

 * Returns the old PTE.

 */

static int mmu_spte_clear_track_bits(u64 *sptep)

static u64 mmu_spte_clear_track_bits(u64 *sptep)

{

	kvm_pfn_t pfn;

	u64 old_spte = *sptep;
@@ -605,7 +605,7 @@ static int mmu_spte_clear_track_bits(u64 *sptep) 
		old_spte = __update_clear_spte_slow(sptep, 0ull);



	if (!is_shadow_present_pte(old_spte))

		return 0;

		return old_spte;



	pfn = spte_to_pfn(old_spte);
@@ -622,7 +622,7 @@ static int mmu_spte_clear_track_bits(u64 *sptep) 
	if (is_dirty_spte(old_spte))

		kvm_set_pfn_dirty(pfn);



	return 1;

	return old_spte;

}



/*
@@ -1119,7 +1119,9 @@ static u64 *rmap_get_next(struct rmap_iterator *iter) 


static void drop_spte(struct kvm *kvm, u64 *sptep)

{

	if (mmu_spte_clear_track_bits(sptep))

	u64 old_spte = mmu_spte_clear_track_bits(sptep);



	if (is_shadow_present_pte(old_spte))

		rmap_remove(kvm, sptep);

}