From: Jason Gunthorpe <jgg@ziepe.ca>
To: Steven Price <steven.price@arm.com>
Cc: "Christian König" <christian.koenig@amd.com>,
"Marc Zyngier" <maz@kernel.org>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Thomas Gleixner" <tglx@kernel.org>,
"T.J. Mercier" <tjmercier@google.com>,
"Benjamin Gaignard" <benjamin.gaignard@collabora.com>,
"Brian Starkey" <Brian.Starkey@arm.com>,
"John Stultz" <jstultz@google.com>,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
"Jiri Pirko" <jiri@resnulli.us>,
"Marek Szyprowski" <m.szyprowski@samsung.com>,
"Suzuki K Poulose" <suzuki.poulose@arm.com>
Subject: Re: [PATCH 0/2] Clear shared pages after private-to-shared conversion
Date: Thu, 20 Aug 2026 09:20:48 -0300 [thread overview]
Message-ID: <20260820122048.GB18100@ziepe.ca> (raw)
In-Reply-To: <20260820105026.53208-1-steven.price@arm.com>
On Thu, Aug 20, 2026 at 11:50:23AM +0100, Steven Price wrote:
> Arm CCA includes "Memory Encryption Contexts" (MEC) which allows the
> private and shared data accessible to a guest to have different memory
> encryption keys. Consequently when converting memory to shared, the
> memory encryption key used to access the physical page will change.
>
> Both the GICv3 ITS driver and the system_cc_shared dma-buf heap
> currently allocate memory with __GFP_ZERO and then decrypt it. With MEC
> the zeroing is done with the wrong encryption key and the data visible
> after decryption may be ciphertext. The RMM is required to scrub the
> data, but may perform this scrub with a different encryption key to the
> eventual key that will be used for shared access.
>
> Fix these two sites by avoiding the __GFP_ZERO during the allocation and
> performing a clear_pages() call after the decryption.
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
This whole set_memory_decrypted() API is awful. It really should be improved.
alloc_pages_decrypted() ?
Jason
next prev parent reply other threads:[~2026-08-20 12:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-20 10:50 [PATCH 0/2] Clear shared pages after private-to-shared conversion Steven Price
2026-08-20 10:50 ` [PATCH 1/2] irqchip/gic-v3-its: Zero shared pages after conversion Steven Price
2026-08-20 12:32 ` Marc Zyngier
2026-08-20 12:55 ` Steven Price
2026-08-20 13:27 ` Jason Gunthorpe
2026-08-20 10:50 ` [PATCH 2/2] dma-buf: heaps: Zero system shared heap " Steven Price
2026-08-20 12:20 ` Jason Gunthorpe [this message]
2026-08-20 17:34 ` [PATCH 0/2] Clear shared pages after private-to-shared conversion Catalin Marinas
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