linux-kernel - [PATCH v3 1/2] KVM: VMX: enable X86_FEATURE

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Message-Id: <20200527140425.3484-2-mlevitsk@redhat.com>
Date:   Wed, 27 May 2020 17:04:24 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Jingqi Liu <jingqi.liu@...el.com>, Tao Xu <tao3.xu@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Joerg Roedel <joro@...tes.org>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Maxim Levitsky <mlevitsk@...hat.com>,
        Krish Sadhukhan <krish.sadhukhan@...cle.com>
Subject: [PATCH v3 1/2] KVM: VMX: enable X86_FEATURE_WAITPKG in KVM capabilities

Even though we might not allow the guest to use WAITPKG's new instructions,
we should tell KVM that the feature is supported by the host CPU.

Note that vmx_waitpkg_supported checks that WAITPKG _can_ be set in the
secondary execution controls as specified by VMX capability MSR,
rather that indicate that we actually enable it for a guest.

Fixes: e69e72faa3a07 (KVM: x86: Add support for user wait instructions)

Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@...el.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@...cle.com>
---
 arch/x86/kvm/vmx/vmx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 55712dd86bafa..fca493d4517c5 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7298,6 +7298,9 @@ static __init void vmx_set_cpu_caps(void)
 	/* CPUID 0x80000001 */
 	if (!cpu_has_vmx_rdtscp())
 		kvm_cpu_cap_clear(X86_FEATURE_RDTSCP);
+
+	if (vmx_waitpkg_supported())
+		kvm_cpu_cap_check_and_set(X86_FEATURE_WAITPKG);
 }
 
 static void vmx_request_immediate_exit(struct kvm_vcpu *vcpu)
-- 
2.26.2