linux-kernel - [PATCH 5.4 088/107] kvm: x86: Toggling CR4.PKE does not load PDPTEs in PAE mode

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Date:   Mon, 24 Aug 2020 10:30:54 +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, Huaitong Han <huaitong.han@...el.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 5.4 088/107] kvm: x86: Toggling CR4.PKE does not load PDPTEs in PAE mode

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

[ Upstream commit cb957adb4ea422bd758568df5b2478ea3bb34f35 ]

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: b9baba8614890 ("KVM, pkeys: expose CPUID/CR4 to guest")
Cc: Huaitong Han <huaitong.han@...el.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: <20200817181655.3716509-1-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 1721a8c8eb26c..8920ee7b28811 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -972,7 +972,7 @@ 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_PKE;
+				   X86_CR4_SMEP;
 
 	if (kvm_valid_cr4(vcpu, cr4))
 		return 1;
-- 
2.25.1