From: Jason Gunthorpe <jgg@ziepe.ca>
To: Leon Romanovsky <leon@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>,
iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev,
Robin Murphy <robin.murphy@arm.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
Steven Price <steven.price@arm.com>,
Suzuki K Poulose <Suzuki.Poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Jiri Pirko <jiri@resnulli.us>,
Mostafa Saleh <smostafa@google.com>,
Petr Tesarik <ptesarik@suse.com>,
Alexey Kardashevskiy <aik@amd.com>,
Dan Williams <dan.j.williams@intel.com>,
Xu Yilun <yilun.xu@linux.intel.com>,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
"Christophe Leroy (CS GROUP)" <chleroy@kernel.org>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
x86@kernel.org, stable@vger.kernel.org,
Michael Kelley <mhklinux@outlook.com>
Subject: Re: [PATCH v8 01/23] dma-direct: return struct page from dma_direct_alloc_from_pool()
Date: Mon, 27 Jul 2026 01:23:57 -0300 [thread overview]
Message-ID: <ambdXXcfgK+cxqxa@ziepe.ca> (raw)
In-Reply-To: <20260726081753.GD12003@unreal>
On Sun, Jul 26, 2026 at 11:17:53AM +0300, Leon Romanovsky wrote:
> Currently, the phys type universally describes memory and can be
> reliably translated into any required representation. It is the most
> fundamental type we have.
You cannot go from phys to page reliably unless you make assumptions
about the phys, that's the whole issue here. If the callchain expects
and intends to use a page it should really stay in a page and not take
a side trip to phys.
I agree it would help to have some helpers that were more phys based
for the callchains that want that since we are mixing two fairly
different activities in these functions..
But making phys the only output out of the pool isn't going to be an
improvement.
BTW how does a struct page even work for decrypted memory? You can't
actually use it that way right? If you try to access it then you'll
get the wrong IPA and it should explode?
Maybe we should be blocking the struct page path entirely for CC
shared?
Jason
next prev parent reply other threads:[~2026-07-27 4:24 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20260717180442.110954-1-aneesh.kumar@kernel.org>
2026-07-17 18:04 ` [PATCH v8 01/23] dma-direct: return struct page from dma_direct_alloc_from_pool() Aneesh Kumar K.V (Arm)
2026-07-21 11:54 ` Leon Romanovsky
2026-07-21 14:20 ` Aneesh Kumar K.V
2026-07-21 14:29 ` Leon Romanovsky
2026-07-21 15:10 ` Aneesh Kumar K.V
2026-07-21 15:33 ` Leon Romanovsky
2026-07-22 19:59 ` Jason Gunthorpe
2026-07-23 7:57 ` Leon Romanovsky
2026-07-25 14:34 ` Jason Gunthorpe
2026-07-26 8:17 ` Leon Romanovsky
2026-07-27 4:23 ` Jason Gunthorpe [this message]
2026-07-27 11:40 ` Leon Romanovsky
2026-07-28 12:31 ` Aneesh Kumar K.V
2026-07-28 14:24 ` Mostafa Saleh
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