From: Bagas Sanjaya <bagasdotme@gmail.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: ankita@nvidia.com, jgg@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, dnigam@nvidia.com, udhoke@nvidia.com,
kvm@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: Wed, 11 Oct 2023 12:45:55 +0700 [thread overview]
Message-ID: <a080c284-e9e3-452a-9ce2-56c93ef04c02@gmail.com> (raw)
In-Reply-To: <20231009133612.3fdd86a9.alex.williamson@redhat.com>
On 10/10/2023 02:36, Alex Williamson wrote:
> On Sun, 8 Oct 2023 07:06:41 +0700
> Bagas Sanjaya <bagasdotme@gmail.com> wrote:
>
>> On Sun, Oct 08, 2023 at 01:52:54AM +0530, ankita@nvidia.com wrote:
>>> 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.
>>>
>>
>> Reading garbage or padding in that case?
>>
>> Confused...
>
> The coherent memory size is rounded to a power-of-2 to be compliant with
> PCI BAR semantics, but reading beyond the implemented size fills the
> return buffer with -1 data, as is common on many platforms when reading
> from an unimplemented section of the address space. Thanks,
>
> Alex
>
Thanks for the explanation!
--
An old man doll... just what I always wanted! - Clara
next prev parent reply other threads:[~2023-10-11 5:46 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 [this message]
2023-10-10 8:42 ` Tian, Kevin
2023-10-10 11:33 ` Jason Gunthorpe
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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