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Subject[PATCH v2 4/4] x86: vmx: Allow direct access to MSR_IA32_ARCH_CAPABILITIES
Date
Add direct access to MSR_IA32_SPEC_CTRL for guests. Future intel processors
will use this MSR to indicate RDCL_NO (bit 0) and IBRS_ALL (bit 1).

Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
---
arch/x86/kvm/cpuid.c | 4 +++-
arch/x86/kvm/vmx.c | 2 ++
2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 32c0c14..2339b1a 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -71,6 +71,7 @@ u64 kvm_supported_xcr0(void)
#define KVM_CPUID_BIT_AVX512_4VNNIW 2
#define KVM_CPUID_BIT_AVX512_4FMAPS 3
#define KVM_CPUID_BIT_IBRS 26
+#define KVM_CPUID_BIT_ARCH_CAPABILITIES 29
#define KF(x) bit(KVM_CPUID_BIT_##x)

int kvm_update_cpuid(struct kvm_vcpu *vcpu)
@@ -394,7 +395,8 @@ 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 =
KF(AVX512_4VNNIW) | KF(AVX512_4FMAPS) | \
- (boot_cpu_has(X86_FEATURE_IBRS) ? KF(IBRS) : 0);
+ (boot_cpu_has(X86_FEATURE_IBRS) ? KF(IBRS) : 0) | \
+ (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES) ? KF(ARCH_CAPABILITIES) : 0);

/* 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 f82a44c..99cb761 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -9617,6 +9617,8 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)

if (boot_cpu_has(X86_FEATURE_IBPB))
vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_PRED_CMD, MSR_TYPE_RW);
+ if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES))
+ vmx_disable_intercept_for_msr(msr_bitmap, MSR_IA32_ARCH_CAPABILITIES, MSR_TYPE_R);
vmx_disable_intercept_for_msr(msr_bitmap, MSR_FS_BASE, MSR_TYPE_RW);
vmx_disable_intercept_for_msr(msr_bitmap, MSR_GS_BASE, MSR_TYPE_RW);
vmx_disable_intercept_for_msr(msr_bitmap, MSR_KERNEL_GS_BASE, MSR_TYPE_RW);
--
2.7.4
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