Commit 4d75f14f authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: MIPS: Mark "struct page" pfns accessed only in "slow" page fault path 



Mark pages accessed only in the slow page fault path in order to remove
an unnecessary user of kvm_pfn_to_refcounted_page().  Marking pages
accessed in the primary MMU during KVM page fault handling isn't harmful,
but it's largely pointless and likely a waste of a cycles since the
primary MMU will call into KVM via mmu_notifiers when aging pages.  I.e.
KVM participates in a "pull" model, so there's no need to also "push"
updates.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Tested-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-ID: <20241010182427.1434605-71-seanjc@google.com>
parent d8f4cda7

arch/mips/kvm/mmu.c

+2 −10
Original line number Diff line number Diff line
@@ -484,8 +484,6 @@ static int _kvm_mips_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, 
	struct kvm *kvm = vcpu->kvm;

	gfn_t gfn = gpa >> PAGE_SHIFT;

	pte_t *ptep;

	kvm_pfn_t pfn = 0;	/* silence bogus GCC warning */

	bool pfn_valid = false;

	int ret = 0;



	spin_lock(&kvm->mmu_lock);
@@ -498,12 +496,9 @@ static int _kvm_mips_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, 
	}



	/* Track access to pages marked old */

	if (!pte_young(*ptep)) {

	if (!pte_young(*ptep))

		set_pte(ptep, pte_mkyoung(*ptep));

		pfn = pte_pfn(*ptep);

		pfn_valid = true;

		/* call kvm_set_pfn_accessed() after unlock */

	}



	if (write_fault && !pte_dirty(*ptep)) {

		if (!pte_write(*ptep)) {

			ret = -EFAULT;
@@ -512,7 +507,6 @@ static int _kvm_mips_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, 


		/* Track dirtying of writeable pages */

		set_pte(ptep, pte_mkdirty(*ptep));

		pfn = pte_pfn(*ptep);

		mark_page_dirty(kvm, gfn);

	}
@@ -523,8 +517,6 @@ static int _kvm_mips_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, 


out:

	spin_unlock(&kvm->mmu_lock);

	if (pfn_valid)

		kvm_set_pfn_accessed(pfn);

	return ret;

}