On Thu, 11 Mar 2021 12:31:48 +0000, Shenming Lu <lushenming@xxxxxxxxxx> wrote: > > On 2021/3/11 17:09, Marc Zyngier wrote: > > I have asked that question in the past: is it actually safe to remap > > the vPEs and expect them to be runnable > > In my opinion, logically it can work, but there might be problems like the > one below that I didn't notice... One thing is that you will have lost interrupts in the meantime (assuming your devices are still alive). How will you make up for that? > > > > > Also, the current code assumes that VMAPP.PTZ can be advertised if a > > VPT is mapped for the first time. Clearly, it is unlikely that the VPT > > will be only populated with 0s, so you'll end up with state corruption > > on the first remap. > > Oh, thanks for pointing it out. > And if we always signal PTZ when alloc = 1, does it mean that we > can't remap the vPE when the VPT is not empty, thus there is no > chance to get the VLPI state? Could we just assume that the VPT is > not empty when first mapping the vPE? I think we should drop the setting of PTZ altogether. It is a silly micro-optimisation, and if the HW can't parse the VPT efficiently when it is empty, then the HW is pretty bad, PTZ or not. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
