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authorSean Christopherson <seanjc@google.com>2021-09-01 13:30:26 -0700
committerPaolo Bonzini <pbonzini@redhat.com>2021-09-22 10:24:01 -0400
commit8646e53633f314e4d746a988240d3b951a92f94a (patch)
tree5815881b9c3784a7e4bfebec986b20f0840d59ea /kernel/entry
parente4e737bb5c170df6135a127739a9e6148ee3da82 (diff)
KVM: rseq: Update rseq when processing NOTIFY_RESUME on xfer to KVM guest
Invoke rseq's NOTIFY_RESUME handler when processing the flag prior to transferring to a KVM guest, which is roughly equivalent to an exit to userspace and processes many of the same pending actions. While the task cannot be in an rseq critical section as the KVM path is reachable only by via ioctl(KVM_RUN), the side effects that apply to rseq outside of a critical section still apply, e.g. the current CPU needs to be updated if the task is migrated. Clearing TIF_NOTIFY_RESUME without informing rseq can lead to segfaults and other badness in userspace VMMs that use rseq in combination with KVM, e.g. due to the CPU ID being stale after task migration. Fixes: 72c3c0fe54a3 ("x86/kvm: Use generic xfer to guest work function") Reported-by: Peter Foley <pefoley@google.com> Bisected-by: Doug Evans <dje@google.com> Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210901203030.1292304-2-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'kernel/entry')
-rw-r--r--kernel/entry/kvm.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/entry/kvm.c b/kernel/entry/kvm.c
index 49972ee99aff..049fd06b4c3d 100644
--- a/kernel/entry/kvm.c
+++ b/kernel/entry/kvm.c
@@ -19,8 +19,10 @@ static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work)
if (ti_work & _TIF_NEED_RESCHED)
schedule();
- if (ti_work & _TIF_NOTIFY_RESUME)
+ if (ti_work & _TIF_NOTIFY_RESUME) {
tracehook_notify_resume(NULL);
+ rseq_handle_notify_resume(NULL, NULL);
+ }
ret = arch_xfer_to_guest_mode_handle_work(vcpu, ti_work);
if (ret)