On Tue, Oct 06, 2020 at 05:24:54PM +0200, Vitaly Kuznetsov wrote: > Vivek Goyal <vgoyal@xxxxxxxxxx> writes: > > So you will have to report token (along with -EFAULT) to user space. So this > > is basically the 3rd proposal which is extension of kvm API and will > > report say HVA/GFN also to user space along with -EFAULT. > > Right, I meant to say that guest kernel has full register state of the > userspace process which caused APF to get queued and instead of trying > to extract it in KVM and pass to userspace in case of a (later) failure > we limit KVM api change to contain token or GFN only and somehow keep > the rest in the guest. This should help with TDX/SEV-ES. Whatever gets reported to userspace should be identical with and without async page faults, i.e. it definitely shouldn't have token information. Note, TDX doesn't allow injection exceptions, so reflecting a #PF back into the guest is not an option. Nor do I think that's "correct" behavior (see everyone's objections to using #PF for APF fixed). I.e. the event should probably be an IRQ.
