Re: [Xen-devel] [PATCH 11/18 V2]: PVH xen: some misc changes like mtrr, intr, msi.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.03.13 at 02:20, Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:
> On Mon, 18 Mar 2013 12:21:11 +0000
> "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> 
>>  >>> On 16.03.13 at 01:46, Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
>>  >>> wrote:
>> > +++ b/xen/arch/x86/msi.c
>> > @@ -787,10 +787,15 @@ static int msix_capability_init(struct
>> > pci_dev *dev, 
>> >      if ( !dev->msix_used_entries )
>> >      {
>> > -        if ( rangeset_add_range(mmio_ro_ranges,
>> > dev->msix_table.first,
>> > +        /* PVH: this is temporary only until linux msi.c is fixed.
>> > See xen-devel
>> > +         * thread: "[PVH]: Help: msi.c".
>> > +         */
>> > +        if ( !is_pvh_domain(dev->domain) &&
>> > +             rangeset_add_range(mmio_ro_ranges,
>> > dev->msix_table.first, dev->msix_table.last) )
>> >              WARN();
>> > -        if ( rangeset_add_range(mmio_ro_ranges,
>> > dev->msix_pba.first,
>> > +        if ( !is_pvh_domain(dev->domain) &&
>> > +             rangeset_add_range(mmio_ro_ranges,
>> > dev->msix_pba.first, dev->msix_pba.last) )
>> >              WARN();
>> >  
>> 
>> As already said before, the whole change above has my explicit
>> NAK.
>> Jan
> 
> Do you have any suggestions? Do you want to hold off on entire xen patch
> until we go fix linux for this? Or can we just omit this change in the next
> V 3 and come back to this later.  Would you be OK with that?

If you can't get MSI (or perhaps just MSI-X) to work properly
for PVH, failing the respective setup operations just for PVH
guests would be the right approach - the guest has to be
prepared to run without MSI generally anyway (minus devices
that have no interrupt pin at all of course). Opening security
holes certainly isn't acceptable, even for code that is considered
experimental only (mostly because it way too easily happens
that the experimental status then gets dropped without
remembering all the pieces that need fixing).

Jan


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