From c44d9b34701dc19792339ae3764ac7b763cb175c Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 29 Sep 2020 21:16:56 -0700 Subject: [PATCH] KVM: x86: Invoke vendor's vcpu_after_set_cpuid() after all common updates Move the call to kvm_x86_ops.vcpu_after_set_cpuid() to the very end of kvm_vcpu_after_set_cpuid() to allow the vendor implementation to react to changes made by the common code. In the near future, this will be used by VMX to update its CR4 guest/host masks to account for reserved bits. In the long term, SGX support will update the allowed XCR0 mask for enclaves based on the vCPU's allowed XCR0. vcpu_after_set_cpuid() (nee kvm_update_cpuid()) was originally added by commit 2acf923e38fb ("KVM: VMX: Enable XSAVE/XRSTOR for guest"), and was called separately after kvm_x86_ops.vcpu_after_set_cpuid() (nee kvm_x86_ops->cpuid_update()). There is no indication that the placement of the common code updates after the vendor updates was anything more than a "new function at the end" decision. Inspection of the current code reveals no dependency on kvm_x86_ops' vcpu_after_set_cpuid() in kvm_vcpu_after_set_cpuid() or any of its helpers. The bulk of the common code depends only on the guest's CPUID configuration, kvm_mmu_reset_context() does not consume dynamic vendor state, and there are no collisions between kvm_pmu_refresh() and VMX's update of PT state. Signed-off-by: Sean Christopherson Message-Id: <20200930041659.28181-3-sean.j.christopherson@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/cpuid.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 5a62fa4..35223eb 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -145,8 +145,6 @@ static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) struct kvm_lapic *apic = vcpu->arch.apic; struct kvm_cpuid_entry2 *best; - kvm_x86_ops.vcpu_after_set_cpuid(vcpu); - best = kvm_find_cpuid_entry(vcpu, 1, 0); if (best && apic) { if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER)) @@ -170,6 +168,9 @@ static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) kvm_pmu_refresh(vcpu); vcpu->arch.cr4_guest_rsvd_bits = __cr4_reserved_bits(guest_cpuid_has, vcpu); + + /* Invoke the vendor callback only after the above state is updated. */ + kvm_x86_ops.vcpu_after_set_cpuid(vcpu); kvm_x86_ops.update_exception_bitmap(vcpu); } -- 2.7.4