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From: Alex Williamson <alex.williamson@redhat.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Ankit Agrawal <ankita@nvidia.com>,
	"Tian, Kevin" <kevin.tian@intel.com>,
	Yishai Hadas <yishaih@nvidia.com>,
	"mst@redhat.com" <mst@redhat.com>,
	"shameerali.kolothum.thodi@huawei.com"
	<shameerali.kolothum.thodi@huawei.com>,
	"clg@redhat.com" <clg@redhat.com>,
	"oleksandr@natalenko.name" <oleksandr@natalenko.name>,
	"K V P, Satyanarayana" <satyanarayana.k.v.p@intel.com>,
	"eric.auger@redhat.com" <eric.auger@redhat.com>,
	"brett.creeley@amd.com" <brett.creeley@amd.com>,
	"horms@kernel.org" <horms@kernel.org>,
	Rahul Rameshbabu <rrameshbabu@nvidia.com>,
	Aniket Agashe <aniketa@nvidia.com>, Neo Jia <cjia@nvidia.com>,
	Kirti Wankhede <kwankhede@nvidia.com>,
	"Tarun Gupta (SW-GPU)" <targupta@nvidia.com>,
	Vikram Sethi <vsethi@nvidia.com>,
	Andy Currid <acurrid@nvidia.com>,
	Alistair Popple <apopple@nvidia.com>,
	John Hubbard <jhubbard@nvidia.com>,
	Dan Williams <danw@nvidia.com>,
	"Anuj Aggarwal (SW-GPU)" <anuaggarwal@nvidia.com>,
	Matt Ochs <mochs@nvidia.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"virtualization@lists.linux-foundation.org"
	<virtualization@lists.linux-foundation.org>
Subject: Re: [PATCH v17 3/3] vfio/nvgrace-gpu: Add vfio pci variant module for grace hopper
Date: Fri, 9 Feb 2024 11:00:44 -0700	[thread overview]
Message-ID: <20240209110044.0cb6707d.alex.williamson@redhat.com> (raw)
In-Reply-To: <20240209171903.GQ10476@nvidia.com>

On Fri, 9 Feb 2024 13:19:03 -0400
Jason Gunthorpe <jgg@nvidia.com> wrote:

> On Fri, Feb 09, 2024 at 08:55:31AM -0700, Alex Williamson wrote:
> > I think Kevin's point is also relative to this latter scenario, in the
> > L1 instance of the nvgrace-gpu driver the mmap of the usemem BAR is
> > cachable, but in the L2 instance of the driver where we only use the
> > vfio-pci-core ops nothing maintains that cachable mapping.  Is that a
> > problem?  An uncached mapping on top of a cachable mapping is often
> > prone to problems.    
> 
> On these CPUs the ARM architecture won't permit it, the L0 level
> blocks uncachable using FWB and page table attributes. The VM, no
> matter what it does, cannot make the cachable memory uncachable.

Great, thanks,

Alex


      reply	other threads:[~2024-02-09 18:00 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-05 23:01 [PATCH v17 0/3] vfio/nvgrace-gpu: Add vfio pci variant module for grace hopper ankita
2024-02-05 23:01 ` [PATCH v17 1/3] vfio/pci: rename and export do_io_rw() ankita
2024-02-08  6:14   ` Tian, Kevin
2024-02-05 23:01 ` [PATCH v17 2/3] vfio/pci: rename and export range_intesect_range ankita
2024-02-08  6:19   ` Tian, Kevin
2024-02-08  6:43     ` Ankit Agrawal
2024-02-05 23:01 ` [PATCH v17 3/3] vfio/nvgrace-gpu: Add vfio pci variant module for grace hopper ankita
2024-02-07 22:32   ` Zhi Wang
2024-02-07 23:27     ` Alex Williamson
2024-02-08  7:12       ` Ankit Agrawal
2024-02-08  7:21         ` Tian, Kevin
2024-02-08 11:13           ` Ankit Agrawal
2024-02-08 16:09           ` Alex Williamson
2024-02-09  9:24             ` Ankit Agrawal
2024-02-07 23:34   ` Alex Williamson
2024-02-08  6:47     ` Ankit Agrawal
2024-02-08  7:14   ` Tian, Kevin
2024-02-09  9:20     ` Ankit Agrawal
2024-02-09 15:55       ` Alex Williamson
2024-02-09 17:19         ` Jason Gunthorpe
2024-02-09 18:00           ` Alex Williamson [this message]

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