Messages in this thread | | | From | Nick Desaulniers <> | Date | Fri, 11 Aug 2023 17:42:04 -0700 | Subject | Re: Hang when booting guest kernels compiled with clang after SRSO mitigations |
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On Fri, Aug 11, 2023 at 9:12 AM Borislav Petkov <bp@alien8.de> wrote: > > On Fri, Aug 11, 2023 at 09:03:18AM -0700, Sean Christopherson wrote: > > Might be the flags bug that borks KVM's fastop() emulation. If that fixes things, > > my guess is that bringing APs out of WFS somehow triggers emulation. > > I was just about to connect you two guys, thanks Sean! > > > https://lore.kernel.org/all/20230811155255.250835-1-seanjc@google.com > > Nathan, if you could test, that would be cool.
Nathan confirmed on IRC (since Sean isn't there; Sean what are you doing, you know we have corp IRCCloud accounts, yeah?):
<nathanchance> bpetkov: Seems like Sean bailed you out :P his patch appears to fix the issue on the Ryzen 3 box, about to test the Threadripper bpetkov: Will have results shortly assuming the machine boots :^) is it possible that clang is generating a code sequence that triggers this issue that gcc does not?
<bpetkov> yeah, something about rFLAGS gets clobbered in the clang variant while gcc doesn't dunno if this is a more serious code generation issue
I'm not familiar enough with the relevant code to make a call there, but perhaps Sean has more context and can help us deduce if that's the case?
> > Also, Nick has another patch for -mno-shared, it probably isn't fixing > yours but it would be good to test it too, just in case: > > https://github.com/ClangBuiltLinux/linux/issues/1911#issuecomment-1674993796
So far it looks like it's working for folks. Fixing that issue is the lowest priority issue of the three we found; I'll send it formally next week.
I literally just had my hard drive fail on my main dev box (that's two machines fail in one week; laptop wont power on anymore; down to one machine left). Going to see if fsck can help at all; worst case I may need Nathan to formally send it for me next week. Let's see if I can recover this machine first...what a way to end the week. SMH
> > Thx! > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette
-- Thanks, ~Nick Desaulniers
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