RE: [PATCH RFC 08/12] iommufd: IOCTLs for the io_pagetable

From: "Tian, Kevin" <kevin.tian@intel.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	Chaitanya Kulkarni <chaitanyak@nvidia.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Daniel Jordan <daniel.m.jordan@oracle.com>,
	David Gibson <david@gibson.dropbear.id.au>,
	Eric Auger <eric.auger@redhat.com>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	Jason Wang <jasowang@redhat.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	"Martins, Joao" <joao.m.martins@oracle.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	Matthew Rosato <mjrosato@linux.ibm.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Nicolin Chen <nicolinc@nvidia.com>,
	Niklas Schnelle <schnelle@linux.ibm.com>,
	Shameerali Kolothum Thodi  <shameerali.kolothum.thodi@huawei.com>,
	"Liu, Yi L" <yi.l.liu@intel.com>,
	Keqian Zhu <zhukeqian1@huawei.com>,
	"Xu, Terrence" <terrence.xu@intel.com>
Subject: RE: [PATCH RFC 08/12] iommufd: IOCTLs for the io_pagetable
Date: Sun, 27 Mar 2022 02:32:23 +0000	[thread overview]
Message-ID: <BN9PR11MB52760D5905410D0907B6260B8C1C9@BN9PR11MB5276.namprd11.prod.outlook.com> (raw)
In-Reply-To: 20220324134622.GB1184709@nvidia.com

> From: Tian, Kevin
> Sent: Friday, March 25, 2022 10:16 AM
> 
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Thursday, March 24, 2022 9:46 PM
> >
> > On Thu, Mar 24, 2022 at 07:25:03AM +0000, Tian, Kevin wrote:
> >
> > > Based on that here is a quick tweak of the force-snoop part (not
> compiled).
> >
> > I liked your previous idea better, that IOMMU_CAP_CACHE_COHERENCY
> > started out OK but got weird. So lets fix it back to the way it was.
> >
> > How about this:
> >
> > https://github.com/jgunthorpe/linux/commits/intel_no_snoop
> >
> > b11c19a4b34c2a iommu: Move the Intel no-snoop control off of
> > IOMMU_CACHE
> > 5263947f9d5f36 vfio: Require that device support DMA cache coherence
> > eab4b381c64a30 iommu: Restore IOMMU_CAP_CACHE_COHERENCY to its
> > original meaning
> > 2752e12bed48f6 iommu: Replace uses of
> IOMMU_CAP_CACHE_COHERENCY
> > with dev_is_dma_coherent()
> >
> > If you like it could you take it from here?
> >
> 
> this looks good to me except that the 2nd patch (eab4b381) should be
> the last one otherwise it affects bisect. and in that case the subject
> would be simply about removing the capability instead of restoring...
> 
> let me find a box to verify it.
> 

My colleague (Terrence) has the environment and helped verify it.

He will give his tested-by after you send out the formal series.

Thanks
Kevin