linux-kernel - [PATCH 16/16] KVM: x86/mmu: WARN if root_hpa is invalid when handling a page fault

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Message-Id: <20191206235729.29263-17-sean.j.christopherson@intel.com>
Date:   Fri,  6 Dec 2019 15:57:29 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 16/16] KVM: x86/mmu: WARN if root_hpa is invalid when handling a page fault

WARN if root_hpa is invalid when handling a page fault.  The check on
root_hpa exists for historical reasons that no longer apply to the
current KVM code base.

Remove an equivalent debug-only warning in direct_page_fault(), whose
existence more or less confirms that root_hpa should always be valid
when handling a page fault.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/mmu/mmu.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 88fd1022731f..32534ea1efd0 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4168,8 +4168,6 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 	kvm_pfn_t pfn;
 	int level, r;
 
-	MMU_WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa));
-
 	if (page_fault_handle_page_track(vcpu, error_code, gfn))
 		return RET_PF_EMULATE;
 
@@ -5459,7 +5457,7 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
 	int r, emulation_type = 0;
 	bool direct = vcpu->arch.mmu->direct_map;
 
-	if (!VALID_PAGE(vcpu->arch.mmu->root_hpa))
+	if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa)))
 		return RET_PF_RETRY;
 
 	/* With shadow page tables, fault_address contains a GVA or nGPA.  */
-- 
2.24.0