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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: 15d4507152 ("KVM/x86: Add IBPB support")
Reported-by: Neel Natu <neelnatu@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jim Mattson 2018-05-22 09:54:20 -07:00 committed by Paolo Bonzini
parent 0e0fee5c53
commit fd65d3142f
1 changed files with 15 additions and 5 deletions
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20
arch/x86/kvm/svm.c
View File

@ -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)