linux-kernel - [PATCH 3.16 02/25] KVM: x86: use Intel speculation bugs and features as derived in generic x86 code

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Message-ID: <lsq.1573602477.729591670@decadent.org.uk>
Date:   Tue, 12 Nov 2019 23:47:59 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Paolo Bonzini" <pbonzini@...hat.com>,
        "Jim Mattson" <jmattson@...gle.com>
Subject: [PATCH 3.16 02/25] KVM: x86: use Intel speculation bugs and
 features as  derived in generic x86 code

3.16.77-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Paolo Bonzini <pbonzini@...hat.com>

commit 0c54914d0c52a15db9954a76ce80fee32cf318f4 upstream.

Similar to AMD bits, set the Intel bits from the vendor-independent
feature and bug flags, because KVM_GET_SUPPORTED_CPUID does not care
about the vendor and they should be set on AMD processors as well.

Suggested-by: Jim Mattson <jmattson@...gle.com>
Reviewed-by: Jim Mattson <jmattson@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/kvm/cpuid.c | 7 +++++++
 arch/x86/kvm/x86.c   | 8 ++++++++
 2 files changed, 15 insertions(+)

--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -395,6 +395,13 @@ static inline int __do_cpuid_ent(struct
 			entry->ebx |= F(TSC_ADJUST);
 			entry->edx &= kvm_cpuid_7_0_edx_x86_features;
 			cpuid_mask(&entry->edx, 10);
+			if (boot_cpu_has(X86_FEATURE_IBPB) &&
+			    boot_cpu_has(X86_FEATURE_IBRS))
+				entry->edx |= F(SPEC_CTRL);
+			if (boot_cpu_has(X86_FEATURE_STIBP))
+				entry->edx |= F(INTEL_STIBP);
+			if (boot_cpu_has(X86_FEATURE_SSBD))
+				entry->edx |= F(SPEC_CTRL_SSBD);
 			/*
 			 * We emulate ARCH_CAPABILITIES in software even
 			 * if the host doesn't support it.
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -917,8 +917,16 @@ u64 kvm_get_arch_capabilities(void)
 
 	rdmsrl_safe(MSR_IA32_ARCH_CAPABILITIES, &data);
 
+	if (!boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
+		data |= ARCH_CAP_RDCL_NO;
+	if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS))
+		data |= ARCH_CAP_SSB_NO;
+	if (!boot_cpu_has_bug(X86_BUG_MDS))
+		data |= ARCH_CAP_MDS_NO;
+
 	return data;
 }
+
 EXPORT_SYMBOL_GPL(kvm_get_arch_capabilities);
 
 bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)