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Message-ID: <BY5PR12MB37635FB280AECC6A4CF59431B01CA@BY5PR12MB3763.namprd12.prod.outlook.com>
Date: Wed, 23 Aug 2023 14:18:52 +0000
From: Ankit Agrawal <ankita@...dia.com>
To: Jason Gunthorpe <jgg@...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
>> +
>> + /*
>> + * 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.
(gdb) p/x *(mr->ops)
$7 = {read = 0xaaab5e0b1c50, write = 0xaaab5e0b1a50, read_with_attrs = 0x0, write_with_attrs = 0x0,
endianness = 0x2, valid = {min_access_size = 0x1, max_access_size = 0x8, unaligned = 0x0, accepts = 0x0},
impl = {min_access_size = 0x1, max_access_size = 0x8, unaligned = 0x0}}
Thanks
Ankit Agrawal
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