[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20231009133612.3fdd86a9.alex.williamson@redhat.com>
Date: Mon, 9 Oct 2023 13:36:12 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: Bagas Sanjaya <bagasdotme@...il.com>
Cc: <ankita@...dia.com>, <jgg@...dia.com>, <yishaih@...dia.com>,
<shameerali.kolothum.thodi@...wei.com>, <kevin.tian@...el.com>,
<aniketa@...dia.com>, <cjia@...dia.com>, <kwankhede@...dia.com>,
<targupta@...dia.com>, <vsethi@...dia.com>, <acurrid@...dia.com>,
<apopple@...dia.com>, <jhubbard@...dia.com>, <danw@...dia.com>,
<anuaggarwal@...dia.com>, <dnigam@...dia.com>, <udhoke@...dia.com>,
<kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v11 1/1] vfio/nvgpu: Add vfio pci variant module for
grace hopper
On Sun, 8 Oct 2023 07:06:41 +0700
Bagas Sanjaya <bagasdotme@...il.com> wrote:
> On Sun, Oct 08, 2023 at 01:52:54AM +0530, ankita@...dia.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
Powered by blists - more mailing lists