On Sat, 10 Jun 2023 at 04:51, Akihiko Odaki <akihiko.odaki@xxxxxxxxxx> wrote: > > On 2022/12/01 20:00, Akihiko Odaki wrote: > > On 2022/12/01 19:40, Peter Maydell wrote: > >> On Thu, 1 Dec 2022 at 10:27, Akihiko Odaki <akihiko.odaki@xxxxxxxxxx> > >> wrote: > >>> > >>> A register access error typically means something seriously wrong > >>> happened so that anything bad can happen after that and recovery is > >>> impossible. > >>> Even failing one register access is catastorophic as > >>> architecture-specific code are not written so that it torelates such > >>> failures. > >>> > >>> Make sure the VM stop and nothing worse happens if such an error occurs. > >>> > >>> Signed-off-by: Akihiko Odaki <akihiko.odaki@xxxxxxxxxx> > >> > >> In a similar vein there was also > >> https://lore.kernel.org/all/20220617144857.34189-1-peterx@xxxxxxxxxx/ > >> back in June, which on the one hand was less comprehensive but on > >> the other does the plumbing to pass the error upwards rather than > >> reporting it immediately at point of failure. > >> > >> I'm in principle in favour but suspect we'll run into some corner > >> cases where we were happily ignoring not-very-important failures > >> (eg if you're running Linux as the host OS on a Mac M1 and your > >> host kernel doesn't have this fix: > >> https://lore.kernel.org/all/YnHz6Cw5ONR2e+KA@xxxxxxxxxx/T/ > >> then QEMU will go from "works by sheer luck" to "consistently > >> hits this error check"). So we should aim to land this extra > >> error checking early in the release cycle so we have plenty of > >> time to deal with any bug reports we get about it. > > Actually I found this problem when I tried to run QEMU with KVM on M2 > > MacBook Air and encountered a failure described and fixed at: > > https://lore.kernel.org/all/20221201104914.28944-2-akihiko.odaki@xxxxxxxxxx/ > > > > Although the affected register was not really important, QEMU couldn't > > run the guest well enough because kvm_arch_put_registers for ARM64 is > > written in a way that it fails early. I guess the situation is not so > > different for other architectures as well. > > > > I still agree that this should be postponed until a new release cycle > > starts as register saving/restoring is too important to fail. > Hi, > > QEMU 8.0 is already released so I think it's time to revisit this. Two months ago would have been a better time :-) We're heading up towards softfreeze for 8.1 in about three weeks from now. thanks -- PMM
