On Thu, Oct 10, 2024 at 6:17 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > On Thu, Oct 10, 2024, Paolo Bonzini wrote: > > On 10/9/24 19:49, Sean Christopherson wrote: > > > Fix a (VMX only) bug reported by Maxim where KVM caches a stale SS.AR_BYTES > > > when involuntary preemption schedules out a vCPU during vmx_vcpu_rest(), and > > > ultimately clobbers the VMCS's SS.AR_BYTES if userspace does KVM_GET_SREGS > > > => KVM_SET_SREGS, i.e. if userspace writes the stale value back into KVM. > > > > > > v4, as this is a spiritual successor to Maxim's earlier series. > > > > > > Patch 1 fixes the underlying problem by avoiding the cache in kvm_sched_out(). > > > > I think we want this one in stable? > > If anything, we should send Maxim's patch to stable trees. While not a complete > fix, it resolves the only known scenario where caching SS.AR_BYTES is truly > problematic, it's as low risk as patches get, and it's much more likely to backport > cleanly to older kernels. Ok, this works for me. Paolo
