From 12c1f6e03f944e399bd2c88441dca5dc702b95a5 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:20 -0700 Subject: [PATCH] KVM: SEV: Free have_run_cpus during VM destruction even if VM is no longer SEV Unconditionally free SEV's "have run CPUs" cpumask in the VM destroy path, i.e. even for what appear to be non-SEV VMs, as an SEV VM becomes a non-SEV VM if its state is intra-host migrated. Alternatively, the mask could be freed in sev_migrate_from() when "converting" the source VM, but that gets annoying because ideally KVM would nullify the mask to guard against UAF, and nullifying the mask would need be conditioned on CPUMASK_OFFSTACK=y. Freeing the mask during sev_migrate_from() is also not robust against other KVM bugs, though that's kind of a moot point since any such bugs would show up even if sev->active is never set. I.e. KVM must get that side of things correct. But, that's not a great reason to add more code just to make things marginally less robust. Fixes: 6f38f8c57464 ("KVM: SVM: Flush cache only on CPUs running SEV guest") Cc: stable@vger.kernel.org Reported-by: Stefan Teodorescu Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-2-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 5705723f1f41..cdc1c04f60da 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2980,13 +2980,17 @@ void sev_vm_destroy(struct kvm *kvm) struct list_head *head = &sev->regions_list; struct list_head *pos, *q; + /* + * Free the mask even if the VM is not *currently* an SEV VM, as it may + * have been an SEV VM prior to intra-host migration. + */ + free_cpumask_var(sev->have_run_cpus); + if (!sev_guest(kvm)) return; WARN_ON(!list_empty(&sev->mirror_vms)); - free_cpumask_var(sev->have_run_cpus); - /* * If this is a mirror VM, remove it from the owner's list of a mirrors * and skip ASID cleanup (the ASID is tied to the lifetime of the owner).