From: Jason Gunthorpe <jgg@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: "ankita@nvidia.com" <ankita@nvidia.com>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"yishaih@nvidia.com" <yishaih@nvidia.com>,
"shameerali.kolothum.thodi@huawei.com"
<shameerali.kolothum.thodi@huawei.com>,
"aniketa@nvidia.com" <aniketa@nvidia.com>,
"cjia@nvidia.com" <cjia@nvidia.com>,
"kwankhede@nvidia.com" <kwankhede@nvidia.com>,
"targupta@nvidia.com" <targupta@nvidia.com>,
"vsethi@nvidia.com" <vsethi@nvidia.com>,
"Currid, Andy" <acurrid@nvidia.com>,
"apopple@nvidia.com" <apopple@nvidia.com>,
"jhubbard@nvidia.com" <jhubbard@nvidia.com>,
"danw@nvidia.com" <danw@nvidia.com>,
"anuaggarwal@nvidia.com" <anuaggarwal@nvidia.com>,
"dnigam@nvidia.com" <dnigam@nvidia.com>,
"udhoke@nvidia.com" <udhoke@nvidia.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v11 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper
Date: Tue, 10 Oct 2023 08:33:57 -0300 [thread overview]
Message-ID: <20231010113357.GG3952@nvidia.com> (raw)
In-Reply-To: <BN9PR11MB52762EE10CBBDF8AB98A53788CCDA@BN9PR11MB5276.namprd11.prod.outlook.com>
On Tue, Oct 10, 2023 at 08:42:13AM +0000, Tian, Kevin wrote:
> > From: ankita@nvidia.com <ankita@nvidia.com>
> > Sent: Sunday, October 8, 2023 4:23 AM
> >
> > PCI BAR are aligned to the power-of-2, but the actual memory on the
> > device may not. A read or write access to the physical address from the
> > last device PFN up to the next power-of-2 aligned physical address
> > results in reading ~0 and dropped writes.
> >
>
> my question to v10 was not answered. posted again:
> --
> Though the variant driver emulates the access to the offset beyond
> the available memory size, how does the userspace driver or the guest
> learn to know the actual size and avoid using the invalid hole to hold
> valid data?
The device FW knows and tells the VM.
Jason
next prev parent reply other threads:[~2023-10-10 11:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-07 20:22 [PATCH v11 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper ankita
2023-10-08 0:06 ` Bagas Sanjaya
2023-10-09 19:36 ` Alex Williamson
2023-10-11 5:45 ` Bagas Sanjaya
2023-10-10 8:42 ` Tian, Kevin
2023-10-10 11:33 ` Jason Gunthorpe [this message]
2023-10-11 2:00 ` Tian, Kevin
2023-10-11 12:00 ` Jason Gunthorpe
2023-10-13 3:43 ` Tian, Kevin
2023-10-13 4:35 ` Ankit Agrawal
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