KVM: x86: add SPEC_CTRL to MSR and CPUID lists

Orabug: 27344012
CVE: CVE-2017-5715

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: John Haxby <john.haxby@oracle.com>
Signed-off-by: Kirtikar Kashyap <kirtikar.kashyap@oracle.com>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 479dd5eb13072ed8e8e430417c5d6e5aed71c5c3..b051031e899a694658a9e04315cf91ab73fb06e0 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -58,6 +58,12 @@ u64 kvm_supported_xcr0(void)
 
 #define F(x) bit(X86_FEATURE_##x)
 
+/* These are scattered features in cpufeatures.h. */
+#define KVM_CPUID_BIT_SPEC_CTRL                26
+#define KVM_CPUID_BIT_STIBP            27
+
+#define KF(x) bit(KVM_CPUID_BIT_##x)
+
 int kvm_update_cpuid(struct kvm_vcpu *vcpu)
 {
        struct kvm_cpuid_entry2 *best;
@@ -354,6 +360,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
        const u32 kvm_supported_word10_x86_features =
                F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | f_xsaves;
 
+       const u32 kvm_cpuid_7_0_edx_x86_features = KF(SPEC_CTRL) | KF(STIBP);
        /* all calls to cpuid_count() should be made on the same cpu */
        get_cpu();
 
@@ -425,11 +432,17 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
                        cpuid_mask(&entry->ebx, 9);
                        // TSC_ADJUST is emulated
                        entry->ebx |= F(TSC_ADJUST);
-               } else
+                       entry->edx &= kvm_cpuid_7_0_edx_x86_features;
+                       if ( !boot_cpu_has(X86_FEATURE_SPEC_CTRL) )
+                               entry->edx &= !(1u << KVM_CPUID_BIT_SPEC_CTRL);
+                       if ( !boot_cpu_has(X86_FEATURE_STIPB) )
+                               entry->edx &= !(1u << KVM_CPUID_BIT_STIBP);
+               } else {
                        entry->ebx = 0;
+                       entry->edx = 0;
+               }
                entry->eax = 0;
                entry->ecx = 0;
-               entry->edx = 0;
                break;
        }
        case 9:

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dd6b8ec121ef2da9478ad8a6bdc85413900e4bb5..a7c32750b4ceb55cb6ad102bde01a7f14264187c 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -941,7 +941,7 @@ static u32 msrs_to_save[] = {
        MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
 #endif
        MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
-       MSR_IA32_FEATURE_CONTROL, MSR_IA32_BNDCFGS
+       MSR_IA32_FEATURE_CONTROL, MSR_IA32_BNDCFGS, MSR_IA32_SPEC_CTRL,
 };
 
 static unsigned num_msrs_to_save;