Re: [PATCH 0/4 v9] MSI-X MMIO support for KVM

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Sep 06, 2011 at 12:16:11PM +0300, Sasha Levin wrote:
> > Back to square #1: We need a device with MSI support and cap bit 8 set
> > in its _MSI_ control word.
> 
> Alright, so I've looked at some of my servers, and one of them has both
> a bunch of MSI-X devices, and some MSI devices which show this:
> 
> 	Capabilities: [60] MSI: Enable+ Count=1/2 Maskable+ 64bit-
> 		Address: 00000020  Data: 0000
> 		Masking: 00000000  Pending: 00000000
> 
> Which would suggest that the support per-vector masking, right?

pciutils has this:

  cap = get_conf_word(d, where + PCI_CAP_FLAGS);

later

  printf("MSI: Enable%c Count=%d/%d Maskable%c 64bit%c\n",
         FLAG(cap, PCI_MSI_FLAGS_ENABLE),
         1 << ((cap & PCI_MSI_FLAGS_QSIZE) >> 4),
         1 << ((cap & PCI_MSI_FLAGS_QMASK) >> 1),
         FLAG(cap, PCI_MSI_FLAGS_MASK_BIT),
         FLAG(cap, PCI_MSI_FLAGS_64BIT));

and
#define  PCI_MSI_FLAGS_MASK_BIT  0x100   /* interrupt masking & reporting supported */

#define PCI_CAP_FLAGS           2       /* Capability defined flags (16 bits) */


So yes, that's bit 8 in control word.


> -- 
> 
> Sasha.