From: Marc Zyngier <maz@kernel.org>
To: Sebastian Ene <sebastianene@google.com>
Cc: oupton@kernel.org, will@kernel.org, ayrton@google.com,
catalin.marinas@arm.com, joey.gouly@arm.com, korneld@google.com,
kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, android-kvm@google.com,
mrigendra.chaubey@gmail.com, perlarsen@google.com,
suzuki.poulose@arm.com, yuzenghui@huawei.com,
stable@vger.kernel.org
Subject: Re: [PATCH] KVM: arm64: Validate the FF-A memory access descriptor placement
Date: Wed, 22 Apr 2026 13:24:02 +0100 [thread overview]
Message-ID: <86bjfb18v1.wl-maz@kernel.org> (raw)
In-Reply-To: <20260422102540.1433704-1-sebastianene@google.com>
On Wed, 22 Apr 2026 11:25:40 +0100,
Sebastian Ene <sebastianene@google.com> wrote:
>
> Prevent the pKVM hypervisor from making assumptions that the
> endpoint memory access descriptor (EMAD) comes right after the
> FF-A memory region header and enforce a strict placement for it
> when validating an FF-A memory lend/share transaction.
As I read this, you want to remove a bad assumption...
>
> Prior to FF-A version 1.1 the header of the memory region
> didn't contain an offset to the endpoint memory access descriptor.
> The layout of a memory transaction looks like this:
>
> Field name | Offset
> -- 0
> [ Header (ffa_mem_region) |__ ep_mem_offset
> EMAD 1 (ffa_mem_region_attributes) |
> ]
>
> Reject the host from specifying a memory access descriptor offset
> that is different than the size of the memory region header.
And yet you decide that you want to enforce this assumption. I don't
understand how you arrive to this conclusion.
Looking at the spec, it appears that the offset is *designed* to allow
a gap between the header and the EMAD. Refusing to handle a it seems to be a
violation of the spec.
What am I missing?
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2026-04-22 12:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-22 10:25 [PATCH] KVM: arm64: Validate the FF-A memory access descriptor placement Sebastian Ene
2026-04-22 12:24 ` Marc Zyngier [this message]
2026-04-22 13:35 ` Sebastian Ene
2026-04-22 19:29 ` Sudeep Holla
2026-04-22 19:17 ` Sudeep Holla
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