linux-kernel - [RFC PATCH v2 04/10] KVM: x86: mmu: tweak fast path for emulation of access to nested NPT pages

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Date:   Thu, 21 Apr 2022 08:12:38 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        intel-gfx@...ts.freedesktop.org,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Zhi Wang <zhi.a.wang@...el.com>,
        Daniel Vetter <daniel@...ll.ch>,
        intel-gvt-dev@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, x86@...nel.org,
        David Airlie <airlied@...ux.ie>,
        Sean Christopherson <seanjc@...gle.com>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <joro@...tes.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [RFC PATCH v2 04/10] KVM: x86: mmu: tweak fast path for emulation of access to nested NPT pages

---
 arch/x86/kvm/mmu/mmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 23f895d439cf5..b63398dfdac3b 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5315,8 +5315,8 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
 	 */
 	if (vcpu->arch.mmu->root_role.direct &&
 	    (error_code & PFERR_NESTED_GUEST_PAGE) == PFERR_NESTED_GUEST_PAGE) {
-		kvm_mmu_unprotect_page(vcpu->kvm, gpa_to_gfn(cr2_or_gpa));
-		return 1;
+		if (kvm_mmu_unprotect_page(vcpu->kvm, gpa_to_gfn(cr2_or_gpa)))
+			return 1;
 	}
 
 	/*
-- 
2.26.3