Re: [Xen-devel] [PATCH] VT-d: honor APEI firmware-first mode in XSA-59 workaround code

["Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>]

Jan Beulich wrote on 2014-06-04:
> When firmware-first mode is being indicated by firmware, we shouldn't 
> be modifying AER registers - these are considered to be owned by 
> firmware in that case. Violating this is being reported to result in 
> SMI storms. While circumventing the workaround means re-exposing 
> affected hosts to the XSA-59 issues, this in any event seems better 
> than not booting at all. Respective messages are being issued to the log, so 
> the situation can be diagnosed.
> 
> The basic building blocks were taken from Linux 3.15-rc. Note that 
> this includes a block of code enclosed in #ifdef CONFIG_X86_MCE - we 
> don't define that symbol, and that code also wouldn't build without 
> suitable machine check side code added; that should happen eventually, but 
> isn't subject of this change.
> 

I am wondering is there any problem if hypervisor to update the ACPI table to 
force it as firmware first. This will avoid dom0 to touch AER unintentionally.

Best regards,
Yang



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