From fd65d3142f734bc4376053c8d75670041903134d Mon Sep 17 00:00:00 2001 From: Jim Mattson Date: Tue, 22 May 2018 09:54:20 -0700 Subject: [PATCH] kvm: svm: Ensure an IBPB on all affected CPUs when freeing a vmcb Previously, we only called indirect_branch_prediction_barrier on the logical CPU that freed a vmcb. This function should be called on all logical CPUs that last loaded the vmcb in question. Fixes: 15d45071523d ("KVM/x86: Add IBPB support") Reported-by: Neel Natu Signed-off-by: Jim Mattson Reviewed-by: Konrad Rzeszutek Wilk Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index a24733aade4c..cc6467b35a85 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -2193,21 +2193,31 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id) return ERR_PTR(err); } +static void svm_clear_current_vmcb(struct vmcb *vmcb) +{ + int i; + + for_each_online_cpu(i) + cmpxchg(&per_cpu(svm_data, i)->current_vmcb, vmcb, NULL); +} + static void svm_free_vcpu(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); + /* + * The vmcb page can be recycled, causing a false negative in + * svm_vcpu_load(). So, ensure that no logical CPU has this + * vmcb page recorded as its current vmcb. + */ + svm_clear_current_vmcb(svm->vmcb); + __free_page(pfn_to_page(__sme_clr(svm->vmcb_pa) >> PAGE_SHIFT)); __free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER); __free_page(virt_to_page(svm->nested.hsave)); __free_pages(virt_to_page(svm->nested.msrpm), MSRPM_ALLOC_ORDER); kvm_vcpu_uninit(vcpu); kmem_cache_free(kvm_vcpu_cache, svm); - /* - * The vmcb page can be recycled, causing a false negative in - * svm_vcpu_load(). So do a full IBPB now. - */ - indirect_branch_prediction_barrier(); } static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)