On Thu, Oct 01, 2020 at 03:12:47AM +0200, Marek Marczykowski-Górecki wrote: > Hi, > > After patching the previous issue ("x86/S3: Fix Shadow Stack resume > path") I still encounter issues resume from S3. > Since I had it working on Xen 4.13 on this particular hardware (Thinkpad > P52), I bisected it and got this: > > commit 4304ff420e51b973ec9eb9dafd64a917dd9c0fb1 > Author: Andrew Cooper <andrew.coop...@citrix.com> > Date: Wed Dec 11 20:59:19 2019 +0000 > > x86/S3: Drop {save,restore}_rest_processor_state() completely > > There is no need to save/restore FS/GS/XCR0 state. It will be handled > suitably on the context switch away from the idle. > > The CR4 restoration in restore_rest_processor_state() was actually > fighting > later code in enter_state() which tried to keep CR4.MCE clear until > everything > was set up. Delete the intermediate restoration, and defer final > restoration > until after MCE is reconfigured. > > Restoring PAT can be done earlier, and ideally before paging is enabled. > By > moving it into the trampoline during the setup for 64bit, the call can be > dropped from cpu_init(). The EFI path boot path doesn't disable paging, > so > make the adjustment when switching onto Xen's pagetables. > > The only remaing piece of restoration is load_system_tables(), so > suspend.c > can be deleted in its entirety. > > Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com> > Reviewed-by: Jan Beulich <jbeul...@suse.com> > > Parent of this commit suspends and resumes just fine. With this commit > applied, it (I think) it panics, at least I get reboot after 5s. Sadly, I > don't have serial console there.
Reading the patch and discussion about it, I think the important details is this uses EFI boot. That may also explain why I haven't see it while bisecting the other S3 issue, where I use legacy boot path. > I tried also master and stable-4.14 with this commit reverted (and also > the other fix applied), but it doesn't work. In this case I get a hang on > resume (power led still flashing, but fan woke up). There are probably > some other dependencies. > > Any idea? > > PS This is different than "Xen crash after S3 suspend - Xen 4.13" > thread, as this one broke with 4.13 -> 4.14 update. > -- Best Regards, Marek Marczykowski-Górecki Invisible Things Lab A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing?
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