Messages in this thread | | | From | Adam Novak <> | Date | Sun, 5 Aug 2018 14:35:14 -0700 | Subject | Re: Problems with Zen under Xen and recent Linux kernel improvements |
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OK, I pulled that commit, 74899d92e66663dc7671a8017b3146dcd4735f3b, in to the Ubuntu kernel and it seems to solve the problem. Now I just need to get Ubuntu to ship it.
Thanks!
On Sun, Aug 5, 2018 at 12:27 PM, Adam Novak <interfect@gmail.com> wrote: > Sorry, I am using Xen version 4.9.2, specifically 4.9.2-0ubuntu1. > > I am seeing the bug with *kernel* version 4.15.0, and specifically > Ubuntu's tag Ubuntu-4.15.0-23.25. That appears to have the "x86/cpu: > Re-apply forced caps every time CPU caps are re-read" patch, but not > "x86/xen: Add call of speculative_store_bypass_ht_init() to PV paths". > > I can try cherry-picking that commit. Are there other commits in > particular that might need to be pulled into the Ubuntu kernel to get > it to work? > > On Tue, Jul 31, 2018 at 4:58 AM, Juergen Gross <jgross@suse.com> wrote: >> 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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