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

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

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=a8036336609d2e184fc3543a4c439c0ba7d7f3a2
>  
> https://xenbits.xen.org/gitweb/?p=qemu-xen.git;a=commit;h=a8036336609d2e184fc3543a4c439c0ba7d7f3a2]
> 
> Signed-off-by: Andra Paraschiv <andraprs@xxxxxxxxxx>

Thanks for doing the backport, LGTM.

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