From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 03/12] KVM: VMX: Recompute "XSAVES enabled" only after CPUID update
Date: Fri, 17 Feb 2023 15:10:13 -0800 [thread overview]
Message-ID: <20230217231022.816138-4-seanjc@google.com> (raw)
In-Reply-To: <20230217231022.816138-1-seanjc@google.com>
Recompute whether or not XSAVES is enabled for the guest only if the
guest's CPUID model changes instead of redoing the computation every time
KVM generates vmcs01's secondary execution controls. The boot_cpu_has()
and cpu_has_vmx_xsaves() checks should never change after KVM is loaded,
and if they do the kernel/KVM is hosed.
Opportunistically add a comment explaining _why_ XSAVES is effectively
exposed to the guest if and only if XSAVE is also exposed to the guest.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/vmx.c | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 47abd9101e68..b6fdb311a7d8 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4620,19 +4620,10 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
if (!enable_pml || !atomic_read(&vcpu->kvm->nr_memslots_dirty_logging))
exec_control &= ~SECONDARY_EXEC_ENABLE_PML;
- if (cpu_has_vmx_xsaves()) {
- /* Exposing XSAVES only when XSAVE is exposed */
- bool xsaves_enabled =
- boot_cpu_has(X86_FEATURE_XSAVE) &&
- guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) &&
- guest_cpuid_has(vcpu, X86_FEATURE_XSAVES);
-
- vcpu->arch.xsaves_enabled = xsaves_enabled;
-
+ if (cpu_has_vmx_xsaves())
vmx_adjust_secondary_exec_control(vmx, &exec_control,
SECONDARY_EXEC_XSAVES,
- xsaves_enabled, false);
- }
+ vcpu->arch.xsaves_enabled, false);
/*
* RDPID is also gated by ENABLE_RDTSCP, turn on the control if either
@@ -7709,8 +7700,15 @@ static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- /* xsaves_enabled is recomputed in vmx_compute_secondary_exec_control(). */
- vcpu->arch.xsaves_enabled = false;
+ /*
+ * XSAVES is effectively enabled if and only if XSAVE is also exposed
+ * to the guest. XSAVES depends on CR4.OSXSAVE, and CR4.OSXSAVE can be
+ * set if and only if XSAVE is supported.
+ */
+ vcpu->arch.xsaves_enabled = cpu_has_vmx_xsaves() &&
+ boot_cpu_has(X86_FEATURE_XSAVE) &&
+ guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) &&
+ guest_cpuid_has(vcpu, X86_FEATURE_XSAVES);
vmx_setup_uret_msrs(vmx);
--
2.39.2.637.g21b0678d19-goog
next prev parent reply other threads:[~2023-02-17 23:10 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-17 23:10 [PATCH 00/12] KVM: x86: Add "governed" X86_FEATURE framework Sean Christopherson
2023-02-17 23:10 ` [PATCH 01/12] KVM: x86: Add a framework for enabling KVM-governed x86 features Sean Christopherson
2023-02-21 17:12 ` Vitaly Kuznetsov
2023-06-29 2:40 ` Binbin Wu
2023-06-29 16:26 ` Sean Christopherson
2023-06-30 8:01 ` Chao Gao
2023-06-30 15:31 ` Sean Christopherson
2023-02-17 23:10 ` [PATCH 02/12] KVM: x86/mmu: Use KVM-governed feature framework to track "GBPAGES enabled" Sean Christopherson
2023-02-17 23:10 ` Sean Christopherson [this message]
2023-02-17 23:10 ` [PATCH 04/12] KVM: VMX: Rename XSAVES control to follow KVM's preferred "ENABLE_XYZ" Sean Christopherson
2023-02-17 23:10 ` [PATCH 05/12] KVM: x86: Use KVM-governed feature framework to track "XSAVES enabled" Sean Christopherson
2023-02-21 14:56 ` Yu Zhang
2023-02-22 18:56 ` Sean Christopherson
2023-02-24 9:54 ` Yu Zhang
2023-02-17 23:10 ` [PATCH 06/12] KVM: nSVM: Use KVM-governed feature framework to track "NRIPS enabled" Sean Christopherson
2023-02-17 23:10 ` [PATCH 07/12] KVM: nSVM: Use KVM-governed feature framework to track "TSC scaling enabled" Sean Christopherson
2023-02-17 23:10 ` [PATCH 08/12] KVM: nSVM: Use KVM-governed feature framework to track "vVM{SAVE,LOAD} enabled" Sean Christopherson
2023-02-21 15:23 ` Yu Zhang
2023-02-21 15:33 ` Yu Zhang
2023-02-21 23:48 ` Sean Christopherson
2023-02-22 6:49 ` Yu Zhang
2023-02-22 16:39 ` Sean Christopherson
2023-02-24 9:25 ` Yu Zhang
2023-02-24 16:16 ` Sean Christopherson
2023-06-29 16:50 ` Sean Christopherson
2023-06-30 10:00 ` Yu Zhang
2023-02-17 23:10 ` [PATCH 09/12] KVM: nSVM: Use KVM-governed feature framework to track "LBRv enabled" Sean Christopherson
2023-02-17 23:10 ` [PATCH 10/12] KVM: nSVM: Use KVM-governed feature framework to track "Pause Filter enabled" Sean Christopherson
2023-02-17 23:10 ` [PATCH 11/12] KVM: nSVM: Use KVM-governed feature framework to track "vGIF enabled" Sean Christopherson
2023-02-17 23:10 ` [PATCH 12/12] KVM: x86: Disallow guest CPUID lookups when IRQs are disabled Sean Christopherson
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