Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot failures

From	Markus Trippelsdorf <markus@trippelsdorf.de>
Newsgroups	linux.kernel
Subject	Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot failures
Date	2015-09-02 13:00 +0200
Message-ID	<q4dVL-2P4-3@gated-at.bofh.it> (permalink)
References	(5 earlier) <q42nD-3aL-5@gated-at.bofh.it> <q47nl-1S4-21@gated-at.bofh.it> <q4cwH-VP-11@gated-at.bofh.it> <q4cGo-17b-49@gated-at.bofh.it> <q4dCq-2s5-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 2015.09.02 at 18:27 +0800, Xiao Guangrong wrote:
> 
> 
> On 09/02/2015 05:38 PM, Markus Trippelsdorf wrote:
> > On 2015.09.02 at 17:17 +0800, Xiao Guangrong wrote:
> >>>
> >>> No. PAT is of course enabled and booting is successful sometimes even
> >>> with the BUG() in allback_mtrr_type(). I suspect a setup (timing) issue.
> >>
> >> Thanks for your confirmation.
> >>
> >>>
> >>> markus@x4 linux % cat .config | grep  X86_PAT
> >>> CONFIG_X86_PAT=y
> >>> markus@x4 linux % dmesg | grep PAT
> >>> [    0.000000] x86/PAT: Configuration [0-7]: WB  WC  UC- UC  WB  WC  UC- WT
> >>
> >> Strange, BP processor has already set WC to PAT1, however KVM does not read it out
> >> from PAT MSR on its local CPU.
> >>
> >> Hmm... PAT default values do not include WC, it seems initing PAT on SP has not
> >> finished after module_init()?
> >>
> >> Could please apply this diff and test it again?
> >
> > (Your patch was malformed.)
> >
> > [    2.138098] kvm: Nested Virtualization enabled
> > [    2.138153] kvm: Nested Paging enabled
> > [    2.138204] KVM PAT: 0x7040600070406.
> 
> So the PAT is the value after CPU reset, it's likely PAT is not initialized on
> the local CPU.

Could it be a simple AMD/INTEL difference. I'm running a AMD CPU and I
see many !use_intel() in if statements in arch/x86/kernel/cpu/mtrr/main.c...

-- 
Markus
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Thread

Re: [GIT PULL] scheduler changes for v4.3 Markus Trippelsdorf <markus@trippelsdorf.de> - 2015-09-01 09:20 +0200
  Re: [GIT PULL] scheduler changes for v4.3 Ingo Molnar <mingo@kernel.org> - 2015-09-01 09:30 +0200
    Re: [GIT PULL] scheduler changes for v4.3 Markus Trippelsdorf <markus@trippelsdorf.de> - 2015-09-01 09:50 +0200
      Re: [GIT PULL] scheduler changes for v4.3 Ingo Molnar <mingo@kernel.org> - 2015-09-01 10:40 +0200
        Re: [GIT PULL] scheduler changes for v4.3 Markus Trippelsdorf <markus@trippelsdorf.de> - 2015-09-01 10:50 +0200
          Re: [GIT PULL] scheduler changes for v4.3 Ingo Molnar <mingo@kernel.org> - 2015-09-01 11:00 +0200
            Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot  failures Markus Trippelsdorf <markus@trippelsdorf.de> - 2015-09-01 12:10 +0200
              Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot  failures Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2015-09-01 15:10 +0200
                Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot  failures Markus Trippelsdorf <markus@trippelsdorf.de> - 2015-09-01 16:00 +0200
                Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot  failures Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2015-09-02 00:40 +0200
                Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot  failures Markus Trippelsdorf <markus@trippelsdorf.de> - 2015-09-02 06:00 +0200
                Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot  failures Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2015-09-02 11:30 +0200
                Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot  failures Markus Trippelsdorf <markus@trippelsdorf.de> - 2015-09-02 11:40 +0200
                Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot  failures Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2015-09-02 12:40 +0200
                Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot  failures Markus Trippelsdorf <markus@trippelsdorf.de> - 2015-09-02 13:00 +0200
                Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot  failures Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2015-09-02 13:10 +0200
        Re: [GIT PULL] scheduler changes for v4.3 Markus Trippelsdorf <markus@trippelsdorf.de> - 2015-09-01 11:00 +0200
    Re: [GIT PULL] scheduler changes for v4.3 Markus Trippelsdorf <markus@trippelsdorf.de> - 2015-09-01 10:20 +0200
      Re: [GIT PULL] scheduler changes for v4.3 Markus Trippelsdorf <markus@trippelsdorf.de> - 2015-09-01 10:40 +0200

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