On 05/07/18 12:19, Juergen Gross wrote: > On 04/07/18 20:16, Karl Johnson wrote: >> Hello, >> >> I'm building dom0 kernel RPMs for the CentOS Xen project >> (https://github.com/CentOS-virt7/xen-kernel) and it seems that the 4.9 >> branch isn't booting anymore as dom0. I recently built 4.9.110 and >> 4.9.111, both give black screen and reboot while booting dom0. Our last >> successful version is 4.9.105 therefore something must be wrong between >> 4.9.106 and 4.9.110. >> >> I checked the OSSTEST for linux-4.9 and the last working flight was >> 4.9.101. Is there a known issue with Xen and Linux 4.9? > > I think I've found the reason. Testing a patch right now.
It worked. I have already sent it to stable. In case you want to try it I'm attaching it for reference. Juergen
>From cc2872574d060fb3d35fd28c81327ee887f540ef Mon Sep 17 00:00:00 2001 From: Juergen Gross <jgr...@suse.com> Date: Thu, 5 Jul 2018 12:29:48 +0200 Subject: [PATCH-for-4.9-stable] x86/cpu: Re-apply forced caps every time CPU caps are re-read Calling get_cpu_cap() will reset a bunch of CPU features. This will cause the system to lose track of force-set and force-cleared features in the words that are reset until the end of CPU initialization. This can cause X86_FEATURE_FPU, for example, to change back and forth during boot and potentially confuse CPU setup. To minimize the chance of confusion, re-apply forced caps every time get_cpu_cap() is called. Signed-off-by: Andy Lutomirski <l...@kernel.org> Reviewed-by: Borislav Petkov <b...@suse.de> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Dave Hansen <dave.han...@linux.intel.com> Cc: Fenghua Yu <fenghua...@intel.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Matthew Whitehead <tedheads...@gmail.com> Cc: Oleg Nesterov <o...@redhat.com> Cc: One Thousand Gnomes <gno...@lxorguk.ukuu.org.uk> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Rik van Riel <r...@redhat.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Yu-cheng Yu <yu-cheng...@intel.com> Link: http://lkml.kernel.org/r/c817eb373d2c67c2c81413a70fc9b845fa34a37e.1484705016.git.l...@kernel.org Signed-off-by: Ingo Molnar <mi...@kernel.org> Signed-off-by: Juergen Gross <jgr...@suse.com> --- upstream commit: 60d3450167433f2d099ce2869dc52dd9e7dc9b29 needed for Xen PV guests to boot, was broken since commit c43b4ff972a986c85bdd8dc1aa05fe23b29ef99c --- arch/x86/kernel/cpu/common.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index b0fd028b2eee..7a4279d8a902 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -848,6 +848,13 @@ void get_cpu_cap(struct cpuinfo_x86 *c) init_scattered_cpuid_features(c); init_speculation_control(c); + + /* + * Clear/Set all flags overridden by options, after probe. + * This needs to happen each time we re-probe, which may happen + * several times during CPU initialization. + */ + apply_forced_caps(c); } static void identify_cpu_without_cpuid(struct cpuinfo_x86 *c) -- 2.13.7
_______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
