linux-kernel - [PATCH 3.2 46/79] KVM: vmx: Inject #GP on invalid PAT CR

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Message-ID: <lsq.1518322806.748610451@decadent.org.uk>
Date:   Sun, 11 Feb 2018 04:20:06 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Paolo Bonzini" <pbonzini@...hat.com>,
        "Nadav Amit" <namit@...technion.ac.il>
Subject: [PATCH 3.2 46/79] KVM: vmx: Inject #GP on invalid PAT CR

3.2.99-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Nadav Amit <namit@...technion.ac.il>

commit 4566654bb9be9e8864df417bb72ceee5136b6a6a upstream.

Guest which sets the PAT CR to invalid value should get a #GP.  Currently, if
vmx supports loading PAT CR during entry, then the value is not checked.  This
patch makes the required check in that case.

Signed-off-by: Nadav Amit <namit@...technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/kvm/vmx.c | 2 ++
 arch/x86/kvm/x86.c | 5 +++--
 arch/x86/kvm/x86.h | 2 ++
 3 files changed, 7 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2204,6 +2204,8 @@ static int vmx_set_msr(struct kvm_vcpu *
 		break;
 	case MSR_IA32_CR_PAT:
 		if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
+			if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data))
+				return 1;
 			vmcs_write64(GUEST_IA32_PAT, data);
 			vcpu->arch.pat = data;
 			break;
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1274,7 +1274,7 @@ static bool valid_mtrr_type(unsigned t)
 	return t < 8 && (1 << t) & 0x73; /* 0, 1, 4, 5, 6 */
 }
 
-static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
+bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 {
 	int i;
 
@@ -1300,12 +1300,13 @@ static bool mtrr_valid(struct kvm_vcpu *
 	/* variable MTRRs */
 	return valid_mtrr_type(data & 0xff);
 }
+EXPORT_SYMBOL_GPL(kvm_mtrr_valid);
 
 static int set_msr_mtrr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 {
 	u64 *p = (u64 *)&vcpu->arch.mtrr_state.fixed_ranges;
 
-	if (!mtrr_valid(vcpu, msr, data))
+	if (!kvm_mtrr_valid(vcpu, msr, data))
 		return 1;
 
 	if (msr == MSR_MTRRdefType) {
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -135,6 +135,8 @@ int kvm_write_guest_virt_system(struct x
 	gva_t addr, void *val, unsigned int bytes,
 	struct x86_exception *exception);
 
+bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data);
+
 extern unsigned int min_timer_period_us;
 
 #endif