Re: [Xen-devel] [PATCH v2] xen: add support for MSI message groups

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 02/28/2014 12:46 PM, Roger Pau Monnà wrote:
> On 28/02/14 18:20, Boris Ostrovsky wrote:
> > On 02/27/2014 01:45 PM, Boris Ostrovsky wrote:
> > > On 02/27/2014 01:15 PM, Roger Pau Monne wrote:
> > > > Add support for MSI message groups for Xen Dom0 using the
> > > > MAP_PIRQ_TYPE_MULTI_MSI pirq map type.
> > > >
> > > > In order to keep track of which pirq is the first one in the group all
> > > > pirqs in the MSI group except for the first one have the newly
> > > > introduced PIRQ_MSI_GROUP flag set. This prevents calling
> > > > PHYSDEVOP_unmap_pirq on them, since the unmap must be done with the
> > > > first pirq in the group.
> > > Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> > I was just looking at xen_setup_msi_irqs() (for a different reason) and
> > I am no longer sure this patch does anything:
> >
> > static int xen_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
> > {
> >          int irq, ret, i;
> >          struct msi_desc *msidesc;
> >          int *v;
> >
> >          if (type == PCI_CAP_ID_MSI && nvec > 1)
> >                  return 1;
> > ....
> >
> > Same thing for xen_hvm_setup_msi_irqs().
> As said in the commit message this is only for Dom0, so the function
> modified is xen_initdom_setup_msi_irqs (were this check is removed).
Then what is the reason for these changes:

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 103e702..905956f 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -178,6 +178,7 @@ static int xen_setup_msi_irqs(struct pci_dev *dev, int 
nvec, int type)
        i = 0;
        list_for_each_entry(msidesc, &dev->msi_list, list) {
                irq = xen_bind_pirq_msi_to_irq(dev, msidesc, v[i],
+                                              (type == PCI_CAP_ID_MSI) ? nvec 
: 1,
                                               (type == PCI_CAP_ID_MSIX) ?
                                               "pcifront-msi-x" :
                                               "pcifront-msi",
@@ -245,6 +246,7 @@ static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int 
nvec, int type)
                                "xen: msi already bound to pirq=%d\n", pirq);
                }
                irq = xen_bind_pirq_msi_to_irq(dev, msidesc, pirq,
+                                              (type == PCI_CAP_ID_MSI) ? nvec 
: 1,
                                               (type == PCI_CAP_ID_MSIX) ?
                                               "msi-x" : "msi",
                                               DOMID_SELF);

Should you simply pass 1?

-boris


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