KVM/VMX: Emulate MSR_IA32_ARCH_CAPABILITIES

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]

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: kvm@vger.kernel.org
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Link: https://lkml.kernel.org/r/1517522386-18410-4-git-send-email-karahmed@amazon.de

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 033004de01e6f7e600a9b7723632a42503119926..1909635fe09c9f848d292fbbd138833c3c3da3b3 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -394,7 +394,7 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 
        /* 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();

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 73acdcf58c4cd7b796d0d94be8205fe7fdad3813..e5f75eb7c459c2d5971b17f9dec9e41df8e20271 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -594,6 +594,8 @@ 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;
@@ -3260,6 +3262,12 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
        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;
@@ -3395,6 +3403,11 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
                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))
@@ -5657,6 +5670,8 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
                ++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);
 

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c53298dfbf50a78c8f1e209e7f52614ec6c4ea36..4ec142e90a34eaec6b9a6669f1d7f258cfec86ee 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1009,6 +1009,7 @@ 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;