[PATCH 0/2] KVM: x86: Fastpath userspace exit fix and hardening

Sean Christopherson
2026-04-23T16:26:30Z

Fix a found-by-inspection bug where KVM could fail to flush the PML buffer
(VMX) or fail to grab the most recet CR0/CR3 (SVM) prior to exiting to
userspace, which could prove to be fatal if that exit is that last exit prior
to save/restore, e.g. the last exit before userspace commits to migrating the
VM.

Patch 2 is related hardening, i.e. isn't fixing any existing bugs (AFAIK).

Sean Christopherson (2):
KVM: x86: Ensure vendor's exit handler runs before fastpath userspace
exits
KVM: SVM: Refresh vcpu->arch.cr{0,3} prior to invoking fastpath
handler

arch/x86/kvm/svm/svm.c | 15 ++++++++-------
arch/x86/kvm/vmx/vmx.c | 3 +++
arch/x86/kvm/x86.c | 3 ---
3 files changed, 11 insertions(+), 10 deletions(-)

base-commit: 85f871f6ba46f20d7fbc0b016b4db648c33220dd
--
2.54.0.545.g6539524ca2-goog