From: Marc Zyngier <maz@kernel.org>
To: Sebastian Ene <sebastianene@google.com>
Cc: catalin.marinas@arm.com, kvmarm@lists.linux.dev,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, android-kvm@google.com,
joey.gouly@arm.com, korneld@google.com,
mrigendra.chaubey@gmail.com, oupton@kernel.org,
perlarsen@google.com, suzuki.poulose@arm.com, will@kernel.org,
yuzenghui@huawei.com
Subject: Re: [PATCH] KVM: arm64: Pass a 64bit function-id in the SMC handlers
Date: Wed, 01 Apr 2026 15:55:11 +0100 [thread overview]
Message-ID: <86341e4to0.wl-maz@kernel.org> (raw)
In-Reply-To: <20260401123201.389906-1-sebastianene@google.com>
On Wed, 01 Apr 2026 13:32:01 +0100,
Sebastian Ene <sebastianene@google.com> wrote:
>
> Make the SMC handlers accept a 64bit value for the function-id to keep
> it uniform with the rest of the code and prevent a u64 -> u32 -> u64
> conversion as it currently happens when we handle PSCI.
That seems overly creative. The spec says (2.5, from ARM DEN 0028 1.6
G):
"The Function Identifier is passed on W0 on every SMC and HVC
call. Its 32-bit integer value indicates which function is being
requested by the caller. It is always passed as the first argument to
every SMC or HVC call in R0 or W0."
which indicates that it is *always* a 32bit value.
So if you have a 64bit value somewhere, *that* should be fixed, not
propagated arbitrarily.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2026-04-01 14:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-01 12:32 [PATCH] KVM: arm64: Pass a 64bit function-id in the SMC handlers Sebastian Ene
2026-04-01 14:55 ` Marc Zyngier [this message]
2026-04-01 17:21 ` Sebastian Ene
2026-04-01 18:28 ` Marc Zyngier
2026-04-01 18:34 ` Marc Zyngier
2026-04-02 18:46 ` Sebastian Ene
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=86341e4to0.wl-maz@kernel.org \
--to=maz@kernel.org \
--cc=android-kvm@google.com \
--cc=catalin.marinas@arm.com \
--cc=joey.gouly@arm.com \
--cc=korneld@google.com \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mrigendra.chaubey@gmail.com \
--cc=oupton@kernel.org \
--cc=perlarsen@google.com \
--cc=sebastianene@google.com \
--cc=suzuki.poulose@arm.com \
--cc=will@kernel.org \
--cc=yuzenghui@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox