Commit 479a1efc authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Drop the intermediate "transient" __kvm_sync_page() 



Nove the kvm_unlink_unsync_page() call out of kvm_sync_page() and into
it's sole caller, and fold __kvm_sync_page() into kvm_sync_page() since
the latter becomes a pure pass-through.  There really should be no reason
for code to do a complete sync of a shadow page outside of the full
kvm_mmu_sync_roots(), e.g. the one use case that creeped in turned out to
be flawed and counter-productive.

Drop the stale comment about @sp->gfn needing to be write-protected, as
it directly contradicts the kvm_mmu_get_page() usage.

No functional change intended.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210622175739.3610207-13-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 07dc4f35

arch/x86/kvm/mmu/mmu.c

+5 −12
Original line number Diff line number Diff line
@@ -1780,8 +1780,7 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, 
	  &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)])	\

		if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else



/* @sp->gfn should be write-protected at the call site */

static bool __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,

static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,

			 struct list_head *invalid_list)

{

	if (vcpu->arch.mmu->sync_page(vcpu, sp) == 0) {
@@ -1830,13 +1829,6 @@ static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp) 
	       unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen);

}



static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,

			 struct list_head *invalid_list)

{

	kvm_unlink_unsync_page(vcpu->kvm, sp);

	return __kvm_sync_page(vcpu, sp, invalid_list);

}



struct mmu_page_path {

	struct kvm_mmu_page *parent[PT64_ROOT_MAX_LEVEL];

	unsigned int idx[PT64_ROOT_MAX_LEVEL];
@@ -1931,6 +1923,7 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu, 
		}



		for_each_sp(pages, sp, parents, i) {

			kvm_unlink_unsync_page(vcpu->kvm, sp);

			flush |= kvm_sync_page(vcpu, sp, &invalid_list);

			mmu_pages_clear_parents(&parents);

		}
@@ -2009,7 +2002,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, 


		if (sp->unsync) {

			/*

			 * The page is good, but is stale.  __kvm_sync_page does

			 * The page is good, but is stale.  kvm_sync_page does

			 * get the latest guest state, but (unlike mmu_unsync_children)

			 * it doesn't write-protect the page or mark it synchronized!

			 * This way the validity of the mapping is ensured, but the
@@ -2020,7 +2013,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, 
			 * If the sync fails, the page is zapped.  If so, break

			 * in order to rebuild it.

			 */

			if (!__kvm_sync_page(vcpu, sp, &invalid_list))

			if (!kvm_sync_page(vcpu, sp, &invalid_list))

				break;



			WARN_ON(!list_empty(&invalid_list));