From: Jason Gunthorpe <jgg@nvidia.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Alex Williamson <alex.williamson@redhat.com>,
ankita@nvidia.com, yishaih@nvidia.com,
shameerali.kolothum.thodi@huawei.com, kevin.tian@intel.com,
aniketa@nvidia.com, cjia@nvidia.com, kwankhede@nvidia.com,
targupta@nvidia.com, vsethi@nvidia.com, acurrid@nvidia.com,
apopple@nvidia.com, jhubbard@nvidia.com, danw@nvidia.com,
anuaggarwal@nvidia.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper
Date: Fri, 8 Sep 2023 09:15:59 -0300 [thread overview]
Message-ID: <ZPsQf9pGrSnbFI8p@nvidia.com> (raw)
In-Reply-To: <ZPrgXAfJvlDLsWqb@infradead.org>
On Fri, Sep 08, 2023 at 01:50:36AM -0700, Christoph Hellwig wrote:
> On Thu, Sep 07, 2023 at 10:04:10PM -0600, Alex Williamson wrote:
> > > I think it really depends on what the qemu side wants to do..
> >
> > Ok, I thought you had been one of the proponents of the fake BAR
> > approach as more resembling CXL.
Yes, I do prefer this because it is ultimately simpler on the qemu and
VM side. This ACPI tinkering is not nice.
> > Do we need to reevaluate that the tinkering with the VM machine
> > topology and firmware tables would better align to a device
> > specific region that QEMU inserts into the VM address space so
> > that bare metal and virtual machine versions of this device look
> > more similar? Thanks,
> Yes, providing something to a VM that doesn't look anything like the
> underlying hardware feels pretty strange.
I don't see the goal as perfect emulation of the real HW.
Aiming for minimally disruptive to the ecosystem to support this
quirky pre-CXL HW.
Perfect emulation would need a unique VFIO uAPI and more complex qemu
changes, and it really brings nothing of value.
Jason
next prev parent reply other threads:[~2023-09-08 12:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-25 12:41 [PATCH v8 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper ankita
2023-09-07 19:55 ` Alex Williamson
2023-09-08 0:34 ` Jason Gunthorpe
2023-09-08 4:04 ` Alex Williamson
2023-09-08 8:50 ` Christoph Hellwig
2023-09-08 12:15 ` Jason Gunthorpe [this message]
2023-09-11 7:12 ` Tian, Kevin
2023-09-11 8:17 ` Ankit Agrawal
2023-09-11 8:24 ` Tian, Kevin
2023-09-11 9:19 ` Ankit Agrawal
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