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

From: Vitaly Kuznetsov
Date: Tue Jul 26 2016 - 09:19:54 EST

David Vrabel <david.vrabel@xxxxxxxxxx> 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.


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