Re: [PATCH v2 35/50] KVM: VMX: Use current CPU's info to perform "disabled by BIOS?" checks
From: Huang, Kai <hidden>
Date: 2022-12-02 12:19:29
Also in:
kvm, kvm-riscv, kvmarm, linux-arm-kernel, linux-mips, linux-riscv, linux-s390, lkml
On Wed, 2022-11-30 at 23:09 +0000, Sean Christopherson wrote:
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 <redacted>
Signed-off-by: Sean Christopherson <seanjc@google.com>Reviewed-by: Kai Huang <redacted>
quoted hunk ↗ jump to hunk
--- 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)