Messages in this thread | | | Subject | Re: commit 3c2e7f7de3 (KVM use NPT page attributes) causes boot failures | From | Xiao Guangrong <> | Date | Wed, 2 Sep 2015 18:27:31 +0800 |
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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.
Maybe something is escaped from stop_machine() called in native_smp_cpus_done(), Ingo?
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