linux-kernel - [PATCH v2 42/66] KVM: x86: Add a helper to check kernel support when setting cpu cap

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Date:   Mon,  2 Mar 2020 15:56:45 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Xiaoyao Li <xiaoyao.li@...el.com>
Subject: [PATCH v2 42/66] KVM: x86: Add a helper to check kernel support when setting cpu cap

Add a helper, kvm_cpu_cap_check_and_set(), to query boot_cpu_has() as
part of setting a KVM cpu capability.  VMX in particular has a number of
features that are dependent on both a VMCS capability and kernel
support.

No functional change intended.

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/cpuid.h   |  6 ++++++
 arch/x86/kvm/svm.c     |  3 +--
 arch/x86/kvm/vmx/vmx.c | 18 ++++++++----------
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index b899ba4bc918..b5155b8b4897 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -273,4 +273,10 @@ static __always_inline void kvm_cpu_cap_set(unsigned int x86_feature)
 	kvm_cpu_caps[x86_leaf] |= __feature_bit(x86_feature);
 }
 
+static __always_inline void kvm_cpu_cap_check_and_set(unsigned int x86_feature)
+{
+	if (boot_cpu_has(x86_feature))
+		kvm_cpu_cap_set(x86_feature);
+}
+
 #endif
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a1317e72824d..d2516283f7db 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1379,8 +1379,7 @@ static __init void svm_set_cpu_caps(void)
 
 	/* CPUID 0x8000000A */
 	/* Support next_rip if host supports it */
-	if (boot_cpu_has(X86_FEATURE_NRIPS))
-		kvm_cpu_cap_set(X86_FEATURE_NRIPS);
+	kvm_cpu_cap_check_and_set(X86_FEATURE_NRIPS);
 
 	if (npt_enabled)
 		kvm_cpu_cap_set(X86_FEATURE_NPT);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 208a40e89a3f..a65b977f30d3 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7143,18 +7143,16 @@ static __init void vmx_set_cpu_caps(void)
 		kvm_cpu_cap_set(X86_FEATURE_VMX);
 
 	/* CPUID 0x7 */
-	if (boot_cpu_has(X86_FEATURE_MPX) && kvm_mpx_supported())
-		kvm_cpu_cap_set(X86_FEATURE_MPX);
-	if (boot_cpu_has(X86_FEATURE_INVPCID) && cpu_has_vmx_invpcid())
-		kvm_cpu_cap_set(X86_FEATURE_INVPCID);
-	if (boot_cpu_has(X86_FEATURE_INTEL_PT) &&
-	    vmx_pt_mode_is_host_guest())
-		kvm_cpu_cap_set(X86_FEATURE_INTEL_PT);
+	if (kvm_mpx_supported())
+		kvm_cpu_cap_check_and_set(X86_FEATURE_MPX);
+	if (cpu_has_vmx_invpcid())
+		kvm_cpu_cap_check_and_set(X86_FEATURE_INVPCID);
+	if (vmx_pt_mode_is_host_guest())
+		kvm_cpu_cap_check_and_set(X86_FEATURE_INTEL_PT);
 
 	/* PKU is not yet implemented for shadow paging. */
-	if (enable_ept && boot_cpu_has(X86_FEATURE_PKU) &&
-	    boot_cpu_has(X86_FEATURE_OSPKE))
-		kvm_cpu_cap_set(X86_FEATURE_PKU);
+	if (enable_ept && boot_cpu_has(X86_FEATURE_OSPKE))
+		kvm_cpu_cap_check_and_set(X86_FEATURE_PKU);
 
 	/* CPUID 0xD.1 */
 	if (!vmx_xsaves_supported())
-- 
2.24.1