From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 18 Oct 2023 12:41:04 -0700 Subject: [PATCH] KVM: nSVM: Advertise support for flush-by-ASID Advertise support for FLUSHBYASID when nested SVM is enabled, as KVM can always emulate flushing TLB entries for a vmcb12 ASID, e.g. by running L2 with a new, fresh ASID in vmcb02. Some modern hypervisors, e.g. VMWare Workstation 17, require FLUSHBYASID support and will refuse to run if it's not present. Punt on proper support, as "Honor L1's request to flush an ASID on nested VMRUN" is one of the TODO items in the (incomplete) list of issues that need to be addressed in order for KVM to NOT do a full TLB flush on every nested SVM transition (see nested_svm_transition_tlb_flush()). Reported-by: Stefan Sterz Closes: https://lkml.kernel.org/r/b9915c9c-4cf6-051a-2d91-44cc6380f455%40proxmox.com Signed-off-by: Sean Christopherson Signed-off-by: Stefan Sterz --- arch/x86/kvm/svm/svm.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index fb9cde86930d..db8028864094 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4921,6 +4921,7 @@ static __init void svm_set_cpu_caps(void) if (nested) { kvm_cpu_cap_set(X86_FEATURE_SVM); kvm_cpu_cap_set(X86_FEATURE_VMCBCLEAN); + kvm_cpu_cap_set(X86_FEATURE_FLUSHBYASID); if (nrips) kvm_cpu_cap_set(X86_FEATURE_NRIPS);