linux-kernel - [PATCH 4.19 079/114] KVM: nVMX: Fix consistency check on injected exception error code

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Date:   Thu, 10 Oct 2019 10:36:26 +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, Nadav Amit <namit@...are.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Jim Mattson <jmattson@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 079/114] KVM: nVMX: Fix consistency check on injected exception error code

From: Sean Christopherson <sean.j.christopherson@...el.com>

[ Upstream commit 567926cca99ba1750be8aae9c4178796bf9bb90b ]

Current versions of Intel's SDM incorrectly state that "bits 31:15 of
the VM-Entry exception error-code field" must be zero.  In reality, bits
31:16 must be zero, i.e. error codes are 16-bit values.

The bogus error code check manifests as an unexpected VM-Entry failure
due to an invalid code field (error number 7) in L1, e.g. when injecting
a #GP with error_code=0x9f00.

Nadav previously reported the bug[*], both to KVM and Intel, and fixed
the associated kvm-unit-test.

[*] https://patchwork.kernel.org/patch/11124749/

Reported-by: Nadav Amit <namit@...are.com>
Cc: stable@...r.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Reviewed-by: Jim Mattson <jmattson@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/kvm/vmx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index d3a900a4fa0e7..6f7b3acdab263 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -12574,7 +12574,7 @@ static int check_vmentry_prereqs(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 
 		/* VM-entry exception error code */
 		if (has_error_code &&
-		    vmcs12->vm_entry_exception_error_code & GENMASK(31, 15))
+		    vmcs12->vm_entry_exception_error_code & GENMASK(31, 16))
 			return VMXERR_ENTRY_INVALID_CONTROL_FIELD;
 
 		/* VM-entry interruption-info field: reserved bits */
-- 
2.20.1