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SubjectRe: [Xen-devel] [PATCH 2/3 v3] Refactor MSI restore call-chain to drop unnecessary argument

On 2013-08-29 15:23, Jan Beulich wrote:
>>>> On 29.08.13 at 04:52, Zhenzhong Duan <zhenzhong.duan@oracle.com> wrote:
>> But in initial domain (aka priviliged guest), it's different.
>> Driver init call graph under initial domain:
>> driver_init->
>> msix_capability_init->
>> msix_program_entries->
>> msix_mask_irq->
>> entry->masked = 1
>> request_irq->
>> __setup_irq->
>> irq_startup->
>> __startup_pirq->
>> EVTCHNOP_bind_pirq hypercall (trap into Xen)
>> [Xen:]
>> pirq_guest_bind->
>> startup_msi_irq->
>> unmask_msi_irq->
>> msi_set_mask_bit->
>> entry->msi_attrib.masked = 0
>>
>> So entry->msi_attrib.masked in xen side always has newest value. entry->masked
>> in initial domain is untouched and is 1 after msix_capability_init.
> And as said several times before - Linux shouldn't be touching
> the MSI-X table at all during initial setup or resume (it should in
> particular not rely on such accesses to not fault, as being a
> privilege violation); all it needs to do is update its software state.
My patch just remove access to msix mask register in dom0. Anything
wrong with that?
>
> Hence fiddling with default_restore_msi_irqs() seems the wrong
> approach towards solving the problem.
dom0 uses xen_initdom_restore_msi_irqs, default_restore_msi_irqs is for
baremetal.

zduan


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