RE: [PATCH v5 13/15] vfio/pci: Expose PCIe PASID capability to guest

From: "Liu, Yi L" <yi.l.liu@intel.com>
To: Auger Eric <eric.auger@redhat.com>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"baolu.lu@linux.intel.com" <baolu.lu@linux.intel.com>,
	"joro@8bytes.org" <joro@8bytes.org>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
	"jacob.jun.pan@linux.intel.com" <jacob.jun.pan@linux.intel.com>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	"Tian, Jun J" <jun.j.tian@intel.com>,
	"Sun, Yi Y" <yi.y.sun@intel.com>,
	"jean-philippe@linaro.org" <jean-philippe@linaro.org>,
	"peterx@redhat.com" <peterx@redhat.com>,
	"Wu, Hao" <hao.wu@intel.com>,
	"stefanha@gmail.com" <stefanha@gmail.com>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v5 13/15] vfio/pci: Expose PCIe PASID capability to guest
Date: Mon, 20 Jul 2020 13:00:14 +0000	[thread overview]
Message-ID: <DM5PR11MB143507550E22674C76F881C0C37B0@DM5PR11MB1435.namprd11.prod.outlook.com> (raw)
In-Reply-To: <63d4c058-246d-1a11-af66-e97fd5ec9bd3@redhat.com>

Hi Eric,

> From: Auger Eric <eric.auger@redhat.com>
> Sent: Monday, July 20, 2020 8:35 PM
> 
> Yi,
> 
> On 7/12/20 1:21 PM, Liu Yi L wrote:
> > This patch exposes PCIe PASID capability to guest for assigned devices.
> > Existing vfio_pci driver hides it from guest by setting the capability
> > length as 0 in pci_ext_cap_length[].
> >
> > And this patch only exposes PASID capability for devices which has PCIe
> > PASID extended struture in its configuration space. So VFs, will will
> s/will//

got it.

> > not see PASID capability on VFs as VF doesn't implement PASID extended
> suggested rewording: VFs will not expose the PASID capability as they do
> not implement the PASID extended structure in their config space?

make sense. will modify it.

> > structure in its configuration space. For VF, it is a TODO in future.
> > Related discussion can be found in below link:
> >
> > https://lkml.org/lkml/2020/4/7/693
> 
> >
> > Cc: Kevin Tian <kevin.tian@intel.com>
> > CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > Cc: Alex Williamson <alex.williamson@redhat.com>
> > Cc: Eric Auger <eric.auger@redhat.com>
> > Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > Cc: Joerg Roedel <joro@8bytes.org>
> > Cc: Lu Baolu <baolu.lu@linux.intel.com>
> > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> > ---
> > v1 -> v2:
> > *) added in v2, but it was sent in a separate patchseries before
> > ---
> >  drivers/vfio/pci/vfio_pci_config.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
> > index d98843f..07ff2e6 100644
> > --- a/drivers/vfio/pci/vfio_pci_config.c
> > +++ b/drivers/vfio/pci/vfio_pci_config.c
> > @@ -95,7 +95,7 @@ static const u16 pci_ext_cap_length[PCI_EXT_CAP_ID_MAX +
> 1] = {
> >  	[PCI_EXT_CAP_ID_LTR]	=	PCI_EXT_CAP_LTR_SIZEOF,
> >  	[PCI_EXT_CAP_ID_SECPCI]	=	0,	/* not yet */
> >  	[PCI_EXT_CAP_ID_PMUX]	=	0,	/* not yet */
> > -	[PCI_EXT_CAP_ID_PASID]	=	0,	/* not yet */
> > +	[PCI_EXT_CAP_ID_PASID]	=	PCI_EXT_CAP_PASID_SIZEOF,
> >  };
> >
> >  /*
> >
> Reviewed-by: Eric Auger <eric.auger@redhat.com>

thanks.

Regards,
Yi Liu

> Thanks
> 
> Eric