linux-kernel - [PATCH 4/4] KVM: x86: simplify kvm_mwait_in

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Date:   Wed,  3 May 2017 21:37:33 +0200
From:   Radim Krčmář <rkrcmar@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Alexander Graf <agraf@...e.de>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        "Gabriel L. Somlo" <gsomlo@...il.com>
Subject: [PATCH 4/4] KVM: x86: simplify kvm_mwait_in_guest()

If Intel/AMD implements MWAIT, we expect that it works well and only
reject known bugs;  no reason to do it the other way around for minor
vendors.  (Not that they are relevant ATM.)

This allows further simplification of kvm_mwait_in_guest().

Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
---
 arch/x86/kvm/x86.h | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 8ea4e80c24d1..b49add75ea35 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -216,17 +216,9 @@ static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec)
 
 static inline bool kvm_mwait_in_guest(void)
 {
-	if (!cpu_has(&boot_cpu_data, X86_FEATURE_MWAIT))
-		return false;
-
-	switch (boot_cpu_data.x86_vendor) {
-	case X86_VENDOR_AMD:
-		return !boot_cpu_has_bug(X86_BUG_AMD_E400);
-	case X86_VENDOR_INTEL:
-		return !boot_cpu_has_bug(X86_BUG_MONITOR);
-	default:
-		return false;
-	}
+	return boot_cpu_has(X86_FEATURE_MWAIT) &&
+		!boot_cpu_has_bug(X86_BUG_AMD_E400) &&
+		!boot_cpu_has_bug(X86_BUG_MONITOR);
 }
 
 #endif
-- 
2.12.2