linux-kernel - Re: [Xen-devel] [PATCH linux v3 0/9] xen: pvhvm: support bootup on secondary vCPUs

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Message-ID: <87lh0ov8nh.fsf@vitty.brq.redhat.com>
Date:	Tue, 26 Jul 2016 15:19:46 +0200
From:	Vitaly Kuznetsov <vkuznets@...hat.com>
To:	David Vrabel <david.vrabel@...rix.com>
Cc:	<xen-devel@...ts.xenproject.org>, Juergen Gross <jgross@...e.com>,
	Stefano Stabellini <sstabellini@...nel.org>,
	Andrew Cooper <andrew.cooper3@...rix.com>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>,
	Julien Grall <julien.grall@....com>,
	Ingo Molnar <mingo@...hat.com>,
	Jan Beulich <JBeulich@...e.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	"Thomas Gleixner" <tglx@...utronix.de>
Subject: Re: [Xen-devel] [PATCH linux v3 0/9] xen: pvhvm: support bootup on secondary vCPUs

David Vrabel <david.vrabel@...rix.com> writes:

> On 26/07/16 13:30, Vitaly Kuznetsov wrote:
>> It may happen that Xen's and Linux's ideas of vCPU id diverge. In
>> particular, when we crash on a secondary vCPU we may want to do kdump
>> and unlike plain kexec where we do migrate_to_reboot_cpu() we try booting
>> on the vCPU which crashed. This doesn't work very well for PVHVM guests as
>> we have a number of hypercalls where we pass vCPU id as a parameter. These
>> hypercalls either fail or do something unexpected. To solve the issue we
>> need to have a mapping between Linux's and Xen's vCPU ids.
>> 
>> This series solves the issue for x86 PVHVM guests. PV guests don't (and
>> probably won't) support kdump so I always assume Xen's vCPU id == Linux's
>> vCPU id. ARM guests will probably need to get proper mapping once we start
>> supporting kexec/kdump there.
>> 
>> Changes since v2:
>> - Use 'uint32_t' for xen_vcpu_id mapping [Julien Grall]
>> - Rebased to linux-4.7
>
> I already applied v2.  If you provide an incremental patch I can queue
> it for 4.9.

Ok,

in that case we can wait till the real mapping is done for ARM to change
the type of xen_vcpu_id I guess.

-- 
  Vitaly