Re: [Xen-devel] [PATCH qemu-xen-traditional] xen/pt: allow QEMU to request MSI unmasking at bind time

["Woodhouse, David" <dwmw@xxxxxxxxxxxx>]

Ian, any objections?

Thanks.On Thu, 2018-06-21 at 08:37 +0000, Paraschiv, Andra-Irina wrote:
> + Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx> for review.
> 
> Thanks, Roger, for review and feedback.
> 
> Andra
> ________________________________________
> From: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Sent: Monday, June 18, 2018 2:43 PM
> To: Paraschiv, Andra-Irina
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; sstabellini@xxxxxxxxxx; jbeulich@
> suse.com; andrew.cooper3@xxxxxxxxxx; Woodhouse, David
> Subject: Re: [PATCH qemu-xen-traditional] xen/pt: allow QEMU to
> request MSI unmasking at bind time
> 
> On Mon, Jun 18, 2018 at 09:35:20AM +0000, Andra Paraschiv wrote:
> > 
> > When a MSI interrupt is bound to a guest using
> > xc_domain_update_msi_irq (XEN_DOMCTL_bind_pt_irq) the interrupt is
> > left masked by default.
> > 
> > This causes problems with guests that first configure interrupts
> > and
> > clean the per-entry MSIX table mask bit and afterwards enable MSIX
> > globally. In such scenario the Xen internal msixtbl handlers would
> > not
> > detect the unmasking of MSIX entries because vectors are not yet
> > registered since MSIX is not enabled, and vectors would be left
> > masked.
> > 
> > Introduce a new flag in the gflags field to signal Xen whether a
> > MSI
> > interrupt should be unmasked after being bound.
> > 
> > This also requires to track the mask register for MSI interrupts,
> > so
> > QEMU can also notify to Xen whether the MSI interrupt should be
> > bound
> > masked or unmasked
> > 
> > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> > Reported-by: Andreas Kinzler <hfp@xxxxxxxxx>
> > Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> > Signed-off-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> > 
> > [Backported from commit a8036336609d2e184fc3543a4c439c0ba7d7f3a2
> >  https://git.qemu.org/?p=qemu.git;a=commit;h=a8036336609d2e184fc354
> > 3a4c439c0ba7d7f3a2
> >  https://xenbits.xen.org/gitweb/?p=qemu-xen.git;a=commit;h=a8036336
> > 609d2e184fc3543a4c439c0ba7d7f3a2]
> > 
> > Signed-off-by: Andra Paraschiv <andraprs@xxxxxxxxxx>
> Thanks for doing the backport, LGTM.
> 
> 
> 
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