linux-kernel - [PATCH 1/8] KVM: x86: add SPEC_CTRL and IBPB

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180109120311.27565-2-pbonzini@redhat.com>
Date:   Tue,  9 Jan 2018 13:03:03 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     rkrcmar@...hat.com, liran.alon@...cle.com, jmattson@...gle.com,
        aliguori@...zon.com, thomas.lendacky@....com, dwmw@...zon.co.uk,
        bp@...en8.de, x86@...nel.org
Subject: [PATCH 1/8] KVM: x86: add SPEC_CTRL and IBPB_SUPPORT accessors

As an interim measure until SPEC_CTRL is supported by upstream
Linux in cpufeatures, add a function that lets vmx.c and svm.c
know whether to save/restore MSR_IA32_SPEC_CTRL.

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/cpuid.c |  3 ---
 arch/x86/kvm/cpuid.h | 22 ++++++++++++++++++++++
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 8e9a07c557f1..767af697c20c 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -67,9 +67,6 @@ u64 kvm_supported_xcr0(void)
 
 #define F(x) bit(X86_FEATURE_##x)
 
-/* These are scattered features in cpufeatures.h. */
-#define KVM_CPUID_BIT_AVX512_4VNNIW     2
-#define KVM_CPUID_BIT_AVX512_4FMAPS     3
 #define KF(x) bit(KVM_CPUID_BIT_##x)
 
 int kvm_update_cpuid(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index c2cea6651279..8d04ccf177ce 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -155,6 +155,28 @@ static inline int guest_cpuid_stepping(struct kvm_vcpu *vcpu)
 	return x86_stepping(best->eax);
 }
 
+/* These are scattered features in cpufeatures.h. */
+#define KVM_CPUID_BIT_AVX512_4VNNIW	2
+#define KVM_CPUID_BIT_AVX512_4FMAPS	3
+#define KVM_CPUID_BIT_SPEC_CTRL		26
+#define KVM_CPUID_BIT_STIBP		27
+
+/* CPUID[eax=0x80000008].ebx */
+#define KVM_CPUID_BIT_IBPB_SUPPORT	12
+
+static inline bool cpu_has_spec_ctrl(void)
+{
+	u32 eax, ebx, ecx, edx;
+	cpuid_count(7, 0, &eax, &ebx, &ecx, &edx);
+
+	return edx & bit(KVM_CPUID_BIT_SPEC_CTRL);
+}
+
+static inline bool cpu_has_ibpb_support(void)
+{
+	return cpuid_ebx(0x80000008) & bit(KVM_CPUID_BIT_IBPB_SUPPORT);
+}
+
 static inline bool supports_cpuid_fault(struct kvm_vcpu *vcpu)
 {
 	return vcpu->arch.msr_platform_info & MSR_PLATFORM_INFO_CPUID_FAULT;
-- 
1.8.3.1