linux-kernel - [PATCH v2 35/50] KVM: VMX: Use current CPU's info to perform "disabled by BIOS?" checks

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Message-ID: <20221130230934.1014142-36-seanjc@google.com>
Date:   Wed, 30 Nov 2022 23:09:19 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>,
        Huacai Chen <chenhuacai@...nel.org>,
        Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
        Anup Patel <anup@...infault.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Eric Farman <farman@...ux.ibm.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Paul Durrant <paul@....org>
Cc:     James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Oliver Upton <oliver.upton@...ux.dev>,
        Atish Patra <atishp@...shpatra.org>,
        David Hildenbrand <david@...hat.com>, kvm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        kvmarm@...ts.cs.columbia.edu, linux-mips@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, Yuan Yao <yuan.yao@...el.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Isaku Yamahata <isaku.yamahata@...el.com>,
        "Philippe Mathieu-Daudé" <philmd@...aro.org>,
        Fabiano Rosas <farosas@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Kai Huang <kai.huang@...el.com>, Chao Gao <chao.gao@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH v2 35/50] KVM: VMX: Use current CPU's info to perform
 "disabled by BIOS?" checks

Use this_cpu_has() instead of boot_cpu_has() to perform the effective
"disabled by BIOS?" checks for VMX.  This will allow consolidating code
between vmx_disabled_by_bios() and vmx_check_processor_compat().

Checking the boot CPU isn't a strict requirement as any divergence in VMX
enabling between the boot CPU and other CPUs will result in KVM refusing
to load thanks to the aforementioned vmx_check_processor_compat().

Furthermore, using the boot CPU was an unintentional change introduced by
commit a4d0b2fdbcf7 ("KVM: VMX: Use VMX feature flag to query BIOS
enabling").  Prior to using the feature flags, KVM checked the raw MSR
value from the current CPU.

Reported-by: Kai Huang <kai.huang@...el.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/vmx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index e859d2b7daa4..3f7d9f88b314 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2492,8 +2492,8 @@ static __init int cpu_has_kvm_support(void)
 
 static __init int vmx_disabled_by_bios(void)
 {
-	return !boot_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
-	       !boot_cpu_has(X86_FEATURE_VMX);
+	return !this_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
+	       !this_cpu_has(X86_FEATURE_VMX);
 }
 
 static int kvm_cpu_vmxon(u64 vmxon_pointer)
-- 
2.38.1.584.g0f3c55d4c2-goog