linux-kernel - [PATCH 5.7 046/163] KVM: VMX: enable X86_FEATURE

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Date:   Tue, 16 Jun 2020 17:33:40 +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, Paolo Bonzini <pbonzini@...hat.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: [PATCH 5.7 046/163] KVM: VMX: enable X86_FEATURE_WAITPKG in KVM capabilities

From: Maxim Levitsky <mlevitsk@...hat.com>

commit 0abcc8f65cc23b65bc8d1614cc64b02b1641ed7c upstream.

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
secondary execution controls as specified by VMX capability MSR, rather
that we actually enable it for a guest.

Cc: stable@...r.kernel.org
Fixes: e69e72faa3a0 ("KVM: x86: Add support for user wait instructions")
Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
Message-Id: <20200523161455.3940-2-mlevitsk@...hat.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/kvm/vmx/vmx.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7138,6 +7138,9 @@ 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)