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From: Jason Gunthorpe <jgg@nvidia.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: kwankhede@nvidia.com, acurrid@nvidia.com, kevin.tian@intel.com,
	yishaih@nvidia.com, cjia@nvidia.com, kvm@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	jhubbard@nvidia.com, dri-devel@lists.freedesktop.org,
	apopple@nvidia.com, ankita@nvidia.com,
	shameerali.kolothum.thodi@huawei.com,
	linux-kernel@vger.kernel.org, vsethi@nvidia.com,
	alex.williamson@redhat.com, targupta@nvidia.com,
	aniketa@nvidia.com, David Airlie <airlied@redhat.com>,
	danw@nvidia.com
Subject: Re: [PATCH v7 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper
Date: Wed, 30 Aug 2023 12:39:05 -0300	[thread overview]
Message-ID: <ZO9imcoN5l28GE9+@nvidia.com> (raw)
In-Reply-To: <ZO9JKKurjv4PsmXh@infradead.org>

On Wed, Aug 30, 2023 at 06:50:32AM -0700, Christoph Hellwig wrote:
> I know I'm chiming in a bit late, but what ultimate user space is going
> to use this?  We should not add anything to the kernel that can't
> be used without fully open user space.

qemu will get the matching VFIO userspace patches, I think they were
posted someplace already.

> vfio has traditionally been a bit special as it "just" passes devices
> through, so any user space could just be a user space driver for a
> random device on $FOO bus, including an actual Linux driver in a VM,
> but this driver has very specific semantics for a very specific piece
> of hardware, so it really needs to be treated like a generic GPU driver
> or accelerator driver.

This is basically a pre-CXL driver. It takes a PCI device and some
non-standard CXL-ish metadata and adapts it to VFIO.

In a post-CXL world this same functionality of managing the 'cache
coherent BAR' for VFIO would be done generically by some generic
vfio-cxl driver.

Jason

       reply	other threads:[~2023-08-30 15:39 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20230822202303.19661-1-ankita@nvidia.com>
     [not found] ` <ZO9JKKurjv4PsmXh@infradead.org>
2023-08-30 15:39   ` Jason Gunthorpe [this message]
     [not found]     ` <ZPCG9/P0fm88E2Zi@infradead.org>
2023-08-31 13:51       ` [PATCH v7 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper Ankit Agrawal
     [not found]         ` <ZPCd2sHXrAZHjsHg@infradead.org>
2023-08-31 18:21           ` Alex Williamson
2023-09-01  0:44             ` Jason Gunthorpe

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