linux-kernel - [PATCH v2 4/4] x86: vmx: Allow direct access to MSR_IA32_ARCH

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Message-Id: <1517187532-32286-5-git-send-email-karahmed@amazon.de>
Date:   Mon, 29 Jan 2018 01:58:52 +0100
From:   KarimAllah Ahmed <karahmed@...zon.de>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     KarimAllah Ahmed <karahmed@...zon.de>,
        Asit Mallick <asit.k.mallick@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Arjan Van De Ven <arjan.van.de.ven@...el.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dan Williams <dan.j.williams@...el.com>,
        Jun Nakajima <jun.nakajima@...el.com>,
        Andy Lutomirski <luto@...nel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ashok Raj <ashok.raj@...el.com>
Subject: [PATCH v2 4/4] x86: vmx: Allow direct access to MSR_IA32_ARCH_CAPABILITIES

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@...el.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Arjan Van De Ven <arjan.van.de.ven@...el.com>
Cc: Tim Chen <tim.c.chen@...ux.intel.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Jun Nakajima <jun.nakajima@...el.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Greg KH <gregkh@...uxfoundation.org>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Ashok Raj <ashok.raj@...el.com>
Signed-off-by: KarimAllah Ahmed <karahmed@...zon.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