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Message-ID: <ef6bc4a4-b307-9bc4-f3be-f7ab7232d303@intel.com>
Date: Thu, 21 Nov 2019 09:52:19 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Borislav Petkov <bp@...en8.de>
Cc: "dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"vkoul@...nel.org" <vkoul@...nel.org>,
"Williams, Dan J" <dan.j.williams@...el.com>,
"Luck, Tony" <tony.luck@...el.com>,
"Lin, Jing" <jing.lin@...el.com>,
"Raj, Ashok" <ashok.raj@...el.com>,
"Kumar, Sanjay K" <sanjay.k.kumar@...el.com>,
"Dey, Megha" <megha.dey@...el.com>,
"Pan, Jacob jun" <jacob.jun.pan@...el.com>,
"Liu, Yi L" <yi.l.liu@...el.com>,
"axboe@...nel.dk" <axboe@...nel.dk>,
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"tglx@...utronix.de" <tglx@...utronix.de>,
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Subject: Re: [PATCH RFC 01/14] x86/asm: add iosubmit_cmds512() based on
movdir64b CPU instruction
On 11/21/19 3:59 AM, Borislav Petkov wrote:
> On Wed, Nov 20, 2019 at 05:10:41PM -0700, Dave Jiang wrote:
>> I'll add the check on the destination address. The call is modeled after
>> __iowrite64_copy() / __iowrite32_copy() in lib/iomap_copy.c. Looks like
>> those functions do not check for the alignment requirements either.
>
> So just because they don't check, you don't need to check either?
No what I mean was those primitives are missing the checks and we should
probably address that at some point.
>
> Can you guarantee that all callers will always do the right thing?
>
> I mean, if you don't care too much, why even write "(must be 512-bit
> aligned)"? Who cares then if the data is aligned or not...
>
>>>> + * @dst: destination, in MMIO space (must be 512-bit aligned)
>>>> + * @src: source
>>>> + * @count: number of 512 bits quantities to submit
>>>
>>> Where's that check on the data?
>>
>> I don't follow?
>
> What do you do if the caller doesn't submit data in 512 bits quantities?
>
How would I detect that? Add a size (in bytes) parameter for the total
source data?
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