linux-kernel - Re: [Xen-devel] [PATCH linux v2 0/9] xen: pvhvm: support bootup on secondary vCPUs

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Message-ID: <aefc934f-a336-36a0-f3dd-de491b57ec11@arm.com>
Date:	Mon, 25 Jul 2016 14:17:23 +0100
From:	Julien Grall <julien.grall@....com>
To:	David Vrabel <david.vrabel@...rix.com>,
	Vitaly Kuznetsov <vkuznets@...hat.com>,
	xen-devel@...ts.xenproject.org
Cc:	Juergen Gross <jgross@...e.com>,
	Stefano Stabellini <sstabellini@...nel.org>,
	Andrew Cooper <andrew.cooper3@...rix.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, 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 v2 0/9] xen: pvhvm: support bootup on
 secondary vCPUs

Hi David,

On 25/07/16 13:38, David Vrabel wrote:
> On 30/06/16 16:56, 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.
>
> Applied to for-linus-4.8, thanks.

It would have been nice to send a ping before applying. This patch 
series is containing Xen ARM code which has not been acked by Stefano, 
nor had feedback from ARM side.

For instance given that all the hypercalls are representing a "vcpu id" 
using "uint32_t" it is a bit weird to use "int" to define xen_vcpu_id 
(see patch #3).

Regards,

-- 
Julien Grall