Re: [Xen-devel] [PATCH QEMU v2] xen/pt: allow QEMU to request MSI unmasking at bind time

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 24.08.17 at 14:19, <roger.pau@xxxxxxxxxx> 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>
> Reported-by: Andreas Kinzler <hfp@xxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>


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