Re: [PATCH v2 1/1] s390/pv: fix the forcing of the swiotlb

From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Will Deacon <will@kernel.org>
Cc: Konrad Rzeszutek Wilk <konrad@darnok.org>,
	Halil Pasic <pasic@linux.ibm.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	Nathan Chancellor <nathan@kernel.org>,
	Vasily Gorbik <gor@linux.ibm.com>,
	linux-s390 <linux-s390@vger.kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	stable@vger.kernel.org, Claire Chang <tientzu@chromium.org>,
	Christoph Hellwig <hch@lst.de>,
	Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH v2 1/1] s390/pv: fix the forcing of the swiotlb
Date: Tue, 27 Jul 2021 15:00:05 +0200	[thread overview]
Message-ID: <827b1bd3-3245-fe0e-0066-cadf8cab432f@de.ibm.com> (raw)
In-Reply-To: <20210727125755.GA18586@willie-the-truck>

On 27.07.21 14:57, Will Deacon wrote:
> On Tue, Jul 27, 2021 at 02:54:14PM +0200, Christian Borntraeger wrote:
>>
>> On 24.07.21 02:27, Konrad Rzeszutek Wilk wrote:
>>> On Sat, Jul 24, 2021 at 01:17:46AM +0200, Halil Pasic wrote:
>>>> Since commit 903cd0f315fe ("swiotlb: Use is_swiotlb_force_bounce for
>>>> swiotlb data bouncing") if code sets swiotlb_force it needs to do so
>>>> before the swiotlb is initialised. Otherwise
>>>> io_tlb_default_mem->force_bounce will not get set to true, and devices
>>>> that use (the default) swiotlb will not bounce despite switolb_force
>>>> having the value of SWIOTLB_FORCE.
>>>>
>>>> Let us restore swiotlb functionality for PV by fulfilling this new
>>>> requirement.
>>>>
>>>> This change addresses what turned out to be a fragility in
>>>> commit 64e1f0c531d1 ("s390/mm: force swiotlb for protected
>>>> virtualization"), which ain't exactly broken in its original context,
>>>> but could give us some more headache if people backport the broken
>>>> change and forget this fix.
>>>>
>>>> Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
>>>> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
>>>> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
>>>> Fixes: 903cd0f315fe ("swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing")
>>>> Fixes: 64e1f0c531d1 ("s390/mm: force swiotlb for protected virtualization")
>>>> Cc: stable@vger.kernel.org #5.3+
>>>>
>>>> ---
>>>
>>> Picked it up and stuck it in linux-next with the other set of patches (Will's fixes).
>>
>> Can you push out to kernel.org?
> 
> It's pushed to the swiotlb tree:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb.git/log/?h=devel/for-linus-5.15
> 
> Since none of the restricted DMA series is in mainline yet, I don't think
> it's needed anywhere else.

Ah right. It is not yet in todays next, so it might just be that yesterdays next pulled
from Konrad too early. Sorry for the noise.