Messages in this thread Patch in this message | | | Date | Wed, 2 Mar 2022 21:39:04 +0100 | Subject | Re: [PATCH v2 4/7] KVM: x86/mmu: Zap only obsolete roots if a root shadow page is zapped | From | Paolo Bonzini <> |
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On 3/2/22 20:45, Sean Christopherson wrote: > AMD NPT is hosed because KVM's awful ASID scheme doesn't assign an ASID per root > and doesn't force a new ASID. IMO, this is an SVM mess and not a TDP MMU bug.
I agree.
> In the short term, I think something like the following would suffice. Long term, > we really need to redo SVM ASID management so that ASIDs are tied to a KVM root.
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index c5e3f219803e..7899ca4748c7 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3857,6 +3857,9 @@ static void svm_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, unsigned long cr3;
if (npt_enabled) { + if (is_tdp_mmu_root(root_hpa)) + svm->current_vmcb->asid_generation = 0; + svm->vmcb->control.nested_cr3 = __sme_set(root_hpa); vmcb_mark_dirty(svm->vmcb, VMCB_NPT);
Why not just new_asid (even unconditionally, who cares)? BTW yeah, the smoke test worked but the actual one failed horribly.
Paolo
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