Messages in this thread | | | Subject | Re: Problems with Zen under Xen and recent Linux kernel improvements | From | Juergen Gross <> | Date | Tue, 31 Jul 2018 13:58:27 +0200 |
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On 31/07/18 03:14, Adam Novak wrote: > Hello, > > I was advised to take this here, and to Boris Ostrovsky and Juergen > Gross, by Thomas Gleixner. > > I am having some trouble with the new speculation control code that > has been added to the Linux kernel, for AMD Zen CPUs. I am running an > AMD Ryzen 7 1700, and I am running Linux as a Xen dom0 (which is part > of the problem; the code seems to work fine running outside of Xen). > > I started having trouble on Ubuntu's commit > 3f6a3b035f91a22c0d3bd27630bf61eac9c8cf6c, "x86/speculation: Handle HT > correctly on AMD", which appears to be cherry-picked from > 1f50ddb4f4189243c05926b842dc1a0332195f31. Since that commit, my system > hangs during the boot process; it starts starting stuff up and trying > to mount things and printing "[OK]" messages, but then fairly early in > the boot process the kernel complains that it is "unable to handle > kernel NULL pointer deference at 000...0008" > > On my Ubuntu bug: > > https://bugs.launchpad.net/bugs/1777338 > > I have a "Screenshot of the null pointer dereference message". It is > running into trouble during a spin lock in the new > speculative_store_bypass_update(). > > Has anyone else seen this behavior on these CPUs under Xen (I am using 4.9)?
You want at least 4.9.112, especially due to the missing patches "x86/xen: Add call of speculative_store_bypass_ht_init() to PV paths", "x86/cpu: Re-apply forced caps every time CPU caps are re-read"
Juergen
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