Patch-mainline: v5.6-rc1

Git-commit: 13c5183a4e643cc2b03a22d0e582c8e17bb7457d

From: Marios Pomonis <pomonis@google.com>

Date: Wed, 11 Dec 2019 12:47:48 -0800

Subject: [PATCH] KVM: x86: Protect MSR-based index computations in pmu.h from

 Spectre-v1/L1TF attacks

References: bsc#1164732

This fixes a Spectre-v1/L1TF vulnerability in the get_gp_pmc() and

get_fixed_pmc() functions.

They both contain index computations based on the (attacker-controlled)

MSR number.

Fixes: 25462f7f5295 ("KVM: x86/vPMU: Define kvm_pmu_ops to support vPMU function dispatch")

Signed-off-by: Nick Finco <nifi@google.com>

Signed-off-by: Marios Pomonis <pomonis@google.com>

Reviewed-by: Andrew Honig <ahonig@google.com>

Cc: stable@vger.kernel.org

Reviewed-by: Jim Mattson <jmattson@google.com>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Juergen Gross <jgross@suse.com>

---

 arch/x86/kvm/pmu.h | 18 ++++++++++++++----

 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h

index 7ebb62326c14..13332984b6d5 100644

--- a/arch/x86/kvm/pmu.h

+++ b/arch/x86/kvm/pmu.h

@@ -1,6 +1,8 @@

 #ifndef __KVM_X86_PMU_H

 #define __KVM_X86_PMU_H

+#include <linux/nospec.h>

+

 #define vcpu_to_pmu(vcpu) (&(vcpu)->arch.pmu)

 #define pmu_to_vcpu(pmu)  (container_of((pmu), struct kvm_vcpu, arch.pmu))

 #define pmc_to_pmu(pmc)   (&(pmc)->vcpu->arch.pmu)

@@ -80,8 +82,12 @@ static inline bool kvm_valid_perf_global_ctrl(struct kvm_pmu *pmu,

 static inline struct kvm_pmc *get_gp_pmc(struct kvm_pmu *pmu, u32 msr,

 					 u32 base)

 {

-	if (msr >= base && msr < base + pmu->nr_arch_gp_counters)

-		return &pmu->gp_counters[msr - base];

+	if (msr >= base && msr < base + pmu->nr_arch_gp_counters) {

+		u32 index = array_index_nospec(msr - base,

+					       pmu->nr_arch_gp_counters);

+

+		return &pmu->gp_counters[index];

+	}

 	return NULL;

 }

@@ -91,8 +97,12 @@ static inline struct kvm_pmc *get_fixed_pmc(struct kvm_pmu *pmu, u32 msr)

 {

 	int base = MSR_CORE_PERF_FIXED_CTR0;

-	if (msr >= base && msr < base + pmu->nr_arch_fixed_counters)

-		return &pmu->fixed_counters[msr - base];

+	if (msr >= base && msr < base + pmu->nr_arch_fixed_counters) {

+		u32 index = array_index_nospec(msr - base,

+					       pmu->nr_arch_fixed_counters);

+

+		return &pmu->fixed_counters[index];

+	}

 	return NULL;

 }

-- 

2.16.4