linux-kernel - Re: [PATCH v7 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZOYWx+ny0bCJYtbD@nvidia.com>
Date:   Wed, 23 Aug 2023 11:25:11 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Ankit Agrawal <ankita@...dia.com>
Cc:     "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        Yishai Hadas <yishaih@...dia.com>,
        "shameerali.kolothum.thodi@...wei.com" 
        <shameerali.kolothum.thodi@...wei.com>,
        "kevin.tian@...el.com" <kevin.tian@...el.com>,
        Aniket Agashe <aniketa@...dia.com>, Neo Jia <cjia@...dia.com>,
        Kirti Wankhede <kwankhede@...dia.com>,
        "Tarun Gupta (SW-GPU)" <targupta@...dia.com>,
        Vikram Sethi <vsethi@...dia.com>,
        Andy Currid <acurrid@...dia.com>,
        Alistair Popple <apopple@...dia.com>,
        John Hubbard <jhubbard@...dia.com>,
        Dan Williams <danw@...dia.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 1/1] vfio/nvgpu: Add vfio pci variant module for grace
 hopper

On Wed, Aug 23, 2023 at 02:18:52PM +0000, Ankit Agrawal wrote:
> >> +
> >> +     /*
> >> +      * Handle read on the BAR2 region. Map to the target device memory
> >> +      * physical address and copy to the request read buffer.
> >> +      */
> >> +     if (copy_to_user(buf, (u8 *)addr + offset, read_count))
> >> +             return -EFAULT;
> >
> > Just to verify, does this memory allow access of arbitrary alignment
> > and size?
> 
> Please correct me if I'm wrong, but based on following gdb dump data on
> the corresponding MemoryRegion->ops, unaligned access isn't supported, and
> a read of size upto 8 may be done.

Regardless, you used MEMREMAP_WB which is equivalent to normal system
memory. It supports all accesses, including atomics, and doesn't
require __iomem accessors.

Jason