Patch "KVM/VMX: Emulate MSR_IA32_ARCH_CAPABILITIES" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

KVM/VMX: Emulate MSR_IA32_ARCH_CAPABILITIES

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
KVMVMX_Emulate_MSR_IA32_ARCH_CAPABILITIES.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Subject: KVM/VMX: Emulate MSR_IA32_ARCH_CAPABILITIES
From: KarimAllah Ahmed [email protected]
Date: Thu Feb 1 22:59:44 2018 +0100

From: KarimAllah Ahmed [email protected]

commit 28c1c9fabf48d6ad596273a11c46e0d0da3e14cd

Intel processors use MSR_IA32_ARCH_CAPABILITIES MSR to indicate RDCL_NO (bit 0) and IBRS_ALL (bit 1). This is a read-only MSR. By default the contents will come directly from the hardware, but user-space can still override it.

[dwmw2: The bit in kvm_cpuid_7_0_edx_x86_features can be unconditional]

---
 arch/x86/kvm/cpuid.c |    2 +-
 arch/x86/kvm/vmx.c   |   15 +++++++++++++++
 arch/x86/kvm/x86.c   |    1 +
 3 files changed, 17 insertions(+), 1 deletion(-)

@@ -394,7 +394,7 @@ static inline int __do_cpuid_ent(struct
 
 	/* cpuid 7.0.edx*/
 	const u32 kvm_cpuid_7_0_edx_x86_features =
-		F(AVX512_4VNNIW) | F(AVX512_4FMAPS);
+		F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(ARCH_CAPABILITIES);
 
 	/* all calls to cpuid_count() should be made on the same cpu */
 	get_cpu();

@@ -583,6 +583,8 @@ struct vcpu_vmx {
 	u64 		      msr_guest_kernel_gs_base;
 #endif
 
+	u64 		      arch_capabilities;
+
 	u32 vm_entry_controls_shadow;
 	u32 vm_exit_controls_shadow;
 	u32 secondary_exec_control;

@@ -3257,6 +3259,12 @@ static int vmx_get_msr(struct kvm_vcpu *
 	case MSR_IA32_TSC:
 		msr_info->data = guest_read_tsc(vcpu);
 		break;
+	case MSR_IA32_ARCH_CAPABILITIES:
+		if (!msr_info->host_initiated &&
+		    !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES))
+			return 1;
+		msr_info->data = to_vmx(vcpu)->arch_capabilities;
+		break;
 	case MSR_IA32_SYSENTER_CS:
 		msr_info->data = vmcs_read32(GUEST_SYSENTER_CS);
 		break;

@@ -3392,6 +3400,11 @@ static int vmx_set_msr(struct kvm_vcpu *
 		vmx_disable_intercept_for_msr(vmx->vmcs01.msr_bitmap, MSR_IA32_PRED_CMD,
 					      MSR_TYPE_W);
 		break;
+	case MSR_IA32_ARCH_CAPABILITIES:
+		if (!msr_info->host_initiated)
+			return 1;
+		vmx->arch_capabilities = data;
+		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))

@@ -5652,6 +5665,8 @@ static int vmx_vcpu_setup(struct vcpu_vm
 		++vmx->nmsrs;
 	}
 
+	if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES))
+		rdmsrl(MSR_IA32_ARCH_CAPABILITIES, vmx->arch_capabilities);
 
 	vm_exit_controls_init(vmx, vmcs_config.vmexit_ctrl);
 

@@ -1006,6 +1006,7 @@ static u32 msrs_to_save[] = {
 #endif
 	MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
 	MSR_IA32_FEATURE_CONTROL, MSR_IA32_BNDCFGS, MSR_TSC_AUX,
+	MSR_IA32_ARCH_CAPABILITIES
 };
 
 static unsigned num_msrs_to_save;

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/x86spectre_Simplify_spectre_v2_command_line_parsing.patch queue-4.14/x86pti_Do_not_enable_PTI_on_CPUs_which_are_not_vulnerable_to_Meltdown.patch queue-4.14/x86speculation_Use_Indirect_Branch_Prediction_Barrier_in_context_switch.patch queue-4.14/x86cpuid_Fix_up_virtual_IBRSIBPBSTIBP_feature_bits_on_Intel.patch queue-4.14/x86cpufeature_Blacklist_SPEC_CTRLPRED_CMD_on_early_Spectre_v2_microcodes.patch queue-4.14/x86cpufeatures_Add_Intel_feature_bits_for_Speculation_Control.patch queue-4.14/x86msr_Add_definitions_for_new_speculation_control_MSRs.patch queue-4.14/KVMVMX_Allow_direct_access_to_MSR_IA32_SPEC_CTRL.patch queue-4.14/x86cpufeatures_Add_CPUID_7_EDX_CPUID_leaf.patch queue-4.14/x86cpufeatures_Add_AMD_feature_bits_for_Speculation_Control.patch queue-4.14/KVMSVM_Allow_direct_access_to_MSR_IA32_SPEC_CTRL.patch queue-4.14/KVMx86_Add_IBPB_support.patch queue-4.14/KVMVMX_Emulate_MSR_IA32_ARCH_CAPABILITIES.patch queue-4.14/x86speculation_Add_basic_IBPB_(Indirect_Branch_Prediction_Barrier)_support.patch queue-4.14/x86speculation_Simplify_indirect_branch_prediction_barrier().patch queue-4.14/x86retpoline_Simplify_vmexit_fill_RSB().patch queue-4.14/x86cpufeatures_Clean_up_Spectre_v2_related_CPUID_flags.patch queue-4.14/KVMx86_Update_the_reverse_cpuid_list_to_include_CPUID_7_EDX.patch queue-4.14/x86retpoline_Avoid_retpolines_for_built-in___init_functions.patch