KVM: SVM: Implement VIRT_SPEC_CTRL support for SSBD

commit bc226f07dcd3c9ef0b7f6236fe356ea4a9cb4769 upstream.

Expose the new virtualized architectural mechanism, VIRT_SSBD, for using
speculative store bypass disable (SSBD) under SVM.  This will allow guests
to use SSBD on hardware that uses non-architectural mechanisms for enabling
SSBD.

[ tglx: Folded the migration fixup from Paolo Bonzini ]

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16:
 - There is no SMM support or cpu_has_high_real_mode_segbase operation
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4af016445a0530ed9a458b585940b8218762beae..f695719a41bda01997c13662e552f162a4566349 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -671,6 +671,7 @@ struct kvm_x86_ops {
        int (*hardware_setup)(void);               /* __init */
        void (*hardware_unsetup)(void);            /* __exit */
        bool (*cpu_has_accelerated_tpr)(void);
+       bool (*has_emulated_msr)(int index);
        void (*cpuid_update)(struct kvm_vcpu *vcpu);
 
        /* Create, but do not attach this VCPU */

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index aaebf24e494672cb919b681b21ba785ea446ccd1..7ab56efa6ed16497766c0bb535e744f13e2a0484 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -700,7 +700,8 @@ static void init_speculation_control(struct cpuinfo_x86 *c)
        if (cpu_has(c, X86_FEATURE_INTEL_STIBP))
                set_cpu_cap(c, X86_FEATURE_STIBP);
 
-       if (cpu_has(c, X86_FEATURE_SPEC_CTRL_SSBD))
+       if (cpu_has(c, X86_FEATURE_SPEC_CTRL_SSBD) ||
+           cpu_has(c, X86_FEATURE_VIRT_SSBD))
                set_cpu_cap(c, X86_FEATURE_SSBD);
 
        if (cpu_has(c, X86_FEATURE_AMD_IBRS)) {

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index a655fe39b6bc6c0574932fededad893c97d79db0..deaedb943249b78426b0917444e949affe25b11d 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -302,7 +302,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 
        /* cpuid 0x80000008.ebx */
        const u32 kvm_cpuid_8000_0008_ebx_x86_features =
-               F(AMD_IBPB) | F(AMD_IBRS);
+               F(AMD_IBPB) | F(AMD_IBRS) | F(VIRT_SSBD);
 
        /* cpuid 0xC0000001.edx */
        const u32 kvm_supported_word5_x86_features =
@@ -524,13 +524,20 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
                        g_phys_as = phys_as;
                entry->eax = g_phys_as | (virt_as << 8);
                entry->edx = 0;
-               /* IBRS and IBPB aren't necessarily present in hardware cpuid */
+               /*
+                * IBRS, IBPB and VIRT_SSBD aren't necessarily present in
+                * hardware cpuid
+                */
                if (boot_cpu_has(X86_FEATURE_AMD_IBPB))
                        entry->ebx |= F(AMD_IBPB);
                if (boot_cpu_has(X86_FEATURE_AMD_IBRS))
                        entry->ebx |= F(AMD_IBRS);
+               if (boot_cpu_has(X86_FEATURE_VIRT_SSBD))
+                       entry->ebx |= F(VIRT_SSBD);
                entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
                cpuid_mask(&entry->ebx, 11);
+               if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD))
+                       entry->ebx |= F(VIRT_SSBD);
                break;
        }
        case 0x80000019:

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index 872ecda3070d492a542378c0df066b7654681927..89f9041e0d6e0ca335aa97547b1e91d5381d1e6c 100644 (file)
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -134,5 +134,13 @@ static inline bool guest_cpuid_has_arch_capabilities(struct kvm_vcpu *vcpu)
        return best && (best->edx & bit(X86_FEATURE_ARCH_CAPABILITIES));
 }
 
+static inline bool guest_cpuid_has_virt_ssbd(struct kvm_vcpu *vcpu)
+{
+       struct kvm_cpuid_entry2 *best;
+
+       best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
+       return best && (best->ebx & bit(X86_FEATURE_VIRT_SSBD));
+}
+
 
 #endif

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index ea3b63fd158c9d758c5b86272acccd4a1882b083..9ac4402cd5933e296a435bd3e169fe293cd9387d 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3151,6 +3151,13 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 
                msr_info->data = svm->spec_ctrl;
                break;
+       case MSR_AMD64_VIRT_SPEC_CTRL:
+               if (!msr_info->host_initiated &&
+                   !guest_cpuid_has_virt_ssbd(vcpu))
+                       return 1;
+
+               msr_info->data = svm->virt_spec_ctrl;
+               break;
        case MSR_IA32_UCODE_REV:
                msr_info->data = 0x01000065;
                break;
@@ -3266,6 +3273,16 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
                        break;
                set_msr_interception(svm->msrpm, MSR_IA32_PRED_CMD, 0, 1);
                break;
+       case MSR_AMD64_VIRT_SPEC_CTRL:
+               if (!msr->host_initiated &&
+                   !guest_cpuid_has_virt_ssbd(vcpu))
+                       return 1;
+
+               if (data & ~SPEC_CTRL_SSBD)
+                       return 1;
+
+               svm->virt_spec_ctrl = data;
+               break;
        case MSR_STAR:
                svm->vmcb->save.star = data;
                break;
@@ -4202,6 +4219,11 @@ static bool svm_cpu_has_accelerated_tpr(void)
        return false;
 }
 
+static bool svm_has_emulated_msr(int index)
+{
+       return true;
+}
+
 static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
 {
        return 0;
@@ -4468,6 +4490,7 @@ static struct kvm_x86_ops svm_x86_ops = {
        .hardware_enable = svm_hardware_enable,
        .hardware_disable = svm_hardware_disable,
        .cpu_has_accelerated_tpr = svm_cpu_has_accelerated_tpr,
+       .has_emulated_msr = svm_has_emulated_msr,
 
        .vcpu_create = svm_create_vcpu,
        .vcpu_free = svm_free_vcpu,

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e64d4621b9cad5358848e394a44764a04c673f67..f931787e067b784cb10aeee1b42054fffccae87c 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7356,6 +7356,17 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu)
                local_irq_enable();
 }
 
+static bool vmx_has_emulated_msr(int index)
+{
+       switch (index) {
+       case MSR_AMD64_VIRT_SPEC_CTRL:
+               /* This is AMD only.  */
+               return false;
+       default:
+               return true;
+       }
+}
+
 static bool vmx_mpx_supported(void)
 {
        return (vmcs_config.vmexit_ctrl & VM_EXIT_CLEAR_BNDCFGS) &&
@@ -9034,6 +9045,7 @@ static struct kvm_x86_ops vmx_x86_ops = {
        .hardware_enable = hardware_enable,
        .hardware_disable = hardware_disable,
        .cpu_has_accelerated_tpr = report_flexpriority,
+       .has_emulated_msr = vmx_has_emulated_msr,
 
        .vcpu_create = vmx_create_vcpu,
        .vcpu_free = vmx_free_vcpu,

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8fddaf37ff4f5e0c179fe738d8c6e9149afb7803..6f38c8385aa9a623267406ba65ec5908213a80fb 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -906,6 +906,7 @@ static u32 emulated_msrs[] = {
        MSR_IA32_MISC_ENABLE,
        MSR_IA32_MCG_STATUS,
        MSR_IA32_MCG_CTL,
+       MSR_AMD64_VIRT_SPEC_CTRL,
 };
 
 static unsigned num_emulated_msrs;
@@ -4039,10 +4040,8 @@ static void kvm_init_msr_list(void)
        num_msrs_to_save = j;
 
        for (i = j = 0; i < ARRAY_SIZE(emulated_msrs); i++) {
-               switch (emulated_msrs[i]) {
-               default:
-                       break;
-               }
+               if (!kvm_x86_ops->has_emulated_msr(emulated_msrs[i]))
+                       continue;
 
                if (j < i)
                        emulated_msrs[j] = emulated_msrs[i];