linux-kernel - [PATCH 4.4 227/266] kvm: x86: Report STIBP on GET_SUPPORTED

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Date:   Wed, 15 May 2019 12:55:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eduardo Habkost <ehabkost@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ben Hutchings <ben@...adent.org.uk>
Subject: [PATCH 4.4 227/266] kvm: x86: Report STIBP on GET_SUPPORTED_CPUID

From: Eduardo Habkost <ehabkost@...hat.com>

commit d7b09c827a6cf291f66637a36f46928dd1423184 upstream.

Months ago, we have added code to allow direct access to MSR_IA32_SPEC_CTRL
to the guest, which makes STIBP available to guests.  This was implemented
by commits d28b387fb74d ("KVM/VMX: Allow direct access to
MSR_IA32_SPEC_CTRL") and b2ac58f90540 ("KVM/SVM: Allow direct access to
MSR_IA32_SPEC_CTRL").

However, we never updated GET_SUPPORTED_CPUID to let userspace know that
STIBP can be enabled in CPUID.  Fix that by updating
kvm_cpuid_8000_0008_ebx_x86_features and kvm_cpuid_7_0_edx_x86_features.

Signed-off-by: Eduardo Habkost <ehabkost@...hat.com>
Reviewed-by: Jim Mattson <jmattson@...gle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
[bwh: Backported to 4.4: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kvm/cpuid.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -344,7 +344,7 @@ static inline int __do_cpuid_ent(struct
 	/* cpuid 0x80000008.ebx */
 	const u32 kvm_cpuid_8000_0008_ebx_x86_features =
 		F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) |
-		F(AMD_SSB_NO);
+		F(AMD_SSB_NO) | F(AMD_STIBP);
 
 	/* cpuid 0xC0000001.edx */
 	const u32 kvm_supported_word5_x86_features =
@@ -365,7 +365,8 @@ static inline int __do_cpuid_ent(struct
 
 	/* cpuid 7.0.edx*/
 	const u32 kvm_cpuid_7_0_edx_x86_features =
-		F(SPEC_CTRL) | F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES);
+		F(SPEC_CTRL) | F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) |
+		F(INTEL_STIBP);
 
 	/* all calls to cpuid_count() should be made on the same cpu */
 	get_cpu();