On Wed, Aug 27, 2025 at 05:01:51PM -0700, Sean Christopherson wrote:
> Check for return to a lower VTL being cancelled separately from handling
> pending TIF-based work, as there is no need to immediately process pending
> work; the kernel will immediately exit to userspace (ignoring preemption)
> and handle the pending work at that time.
>
> Disentangling cancellation from the TIF-based work will allow switching to
> common virtualization APIs for detecting and processing pending work.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Thanks for this patch, Sean.
My current plan is to drop this driver from my tree (hence it will
disappear from linux-next soon) because Peter has an objection to the
ABI it introduces. I just have not gotten around to it yet.
I won't apply this patch, the next one and the last one. I have CC'ed
the owner of that driver to this patch here so that your suggestion can
be incorporated in future submissions.
CC Saurabh and Naman.
Thanks,
Wei
> ---
> drivers/hv/mshv_vtl_main.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
> index 12f5e77b7095..aa09a76f0eff 100644
> --- a/drivers/hv/mshv_vtl_main.c
> +++ b/drivers/hv/mshv_vtl_main.c
> @@ -731,19 +731,21 @@ static int mshv_vtl_ioctl_return_to_lower_vtl(void)
> _TIF_NOTIFY_RESUME | _TIF_NOTIFY_SIGNAL |
> _TIF_NEED_RESCHED_LAZY;
> unsigned long ti_work;
> - u32 cancel;
> unsigned long irq_flags;
> struct hv_vp_assist_page *hvp;
> int ret;
>
> local_irq_save(irq_flags);
> + if (READ_ONCE(mshv_vtl_this_run()->cancel)) {
> + local_irq_restore(irq_flags);
> + preempt_enable();
> + return -EINTR;
> + }
> +
> ti_work = READ_ONCE(current_thread_info()->flags);
> - cancel = READ_ONCE(mshv_vtl_this_run()->cancel);
> - if (unlikely((ti_work & VTL0_WORK) || cancel)) {
> + if (unlikely(ti_work & VTL0_WORK)) {
> local_irq_restore(irq_flags);
> preempt_enable();
> - if (cancel)
> - ti_work |= _TIF_SIGPENDING;
> ret = mshv_do_pre_guest_mode_work(ti_work);
> if (ret)
> return ret;
> --
> 2.51.0.268.g9569e192d0-goog
>
>