linux-kernel - [PATCH 4.19 52/71] kvm: x86: Toggling CR4.SMAP does not load PDPTEs in PAE mode

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Date:   Mon, 24 Aug 2020 10:31:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Xiao Guangrong <guangrong.xiao@...ux.intel.com>,
        Jim Mattson <jmattson@...gle.com>,
        Peter Shier <pshier@...gle.com>,
        Oliver Upton <oupton@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 52/71] kvm: x86: Toggling CR4.SMAP does not load PDPTEs in PAE mode

From: Jim Mattson <jmattson@...gle.com>

[ Upstream commit 427890aff8558eb4326e723835e0eae0e6fe3102 ]

See the SDM, volume 3, section 4.4.1:

If PAE paging would be in use following an execution of MOV to CR0 or
MOV to CR4 (see Section 4.1.1) and the instruction is modifying any of
CR0.CD, CR0.NW, CR0.PG, CR4.PAE, CR4.PGE, CR4.PSE, or CR4.SMEP; then
the PDPTEs are loaded from the address in CR3.

Fixes: 0be0226f07d14 ("KVM: MMU: fix SMAP virtualization")
Cc: Xiao Guangrong <guangrong.xiao@...ux.intel.com>
Signed-off-by: Jim Mattson <jmattson@...gle.com>
Reviewed-by: Peter Shier <pshier@...gle.com>
Reviewed-by: Oliver Upton <oupton@...gle.com>
Message-Id: <20200817181655.3716509-2-jmattson@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5b2440e591fc1..ff1f764c4709a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -857,7 +857,7 @@ int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 {
 	unsigned long old_cr4 = kvm_read_cr4(vcpu);
 	unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE |
-				   X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_PKE;
+				   X86_CR4_SMEP | X86_CR4_PKE;
 
 	if (kvm_valid_cr4(vcpu, cr4))
 		return 1;
-- 
2.25.1