From: Marc Zyngier <maz@kernel.org>
To: Sebastian Ene <sebastianene@google.com>
Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, android-kvm@google.com,
catalin.marinas@arm.com, joey.gouly@arm.com,
mark.rutland@arm.com, oupton@kernel.org, suzuki.poulose@arm.com,
tabba@google.com, vdonnefort@google.com, will@kernel.org,
yuzenghui@huawei.com
Subject: Re: [PATCH] KVM: arm64: Inject UNDEF when host is executing an smc with imm16 != 0
Date: Tue, 24 Mar 2026 14:43:27 +0000 [thread overview]
Message-ID: <86tsu547ao.wl-maz@kernel.org> (raw)
In-Reply-To: <20260324135728.3532400-1-sebastianene@google.com>
On Tue, 24 Mar 2026 13:57:28 +0000,
Sebastian Ene <sebastianene@google.com> wrote:
>
> The ARM Service Calling Convention (SMCCC) specifies that the function
> identifier and parameters should be passed in registers, leaving the
> 16-bit immediate field of the SMC instruction un-handled.
> Currently, our pKVM handler ignores the immediate value, which could lead
> to non-compliant software relying on implementation-defined behavior.
> Enforce the host kernel running under pKVM to use an immediate value
> of 0 by decoding the ISS from the ESR_EL2 and inject an undefined
> instruction exception back to the caller.
No, that's completely wrong. SMC never UNDEFs, unless EL3 isn't
implemented. You can't just decide to generate an UNDEF because you
don't like the immediate.
All you are allowed to do is to return an error code.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2026-03-24 14:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-24 13:57 [PATCH] KVM: arm64: Inject UNDEF when host is executing an smc with imm16 != 0 Sebastian Ene
2026-03-24 14:06 ` Vincent Donnefort
2026-03-24 14:09 ` Vincent Donnefort
2026-03-24 14:18 ` Vincent Donnefort
2026-03-24 15:05 ` Sebastian Ene
2026-03-24 14:41 ` Sebastian Ene
2026-03-24 14:43 ` Marc Zyngier [this message]
2026-03-24 15:04 ` Sebastian Ene
2026-03-24 15:13 ` Fuad Tabba
2026-03-25 10:01 ` 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=86tsu547ao.wl-maz@kernel.org \
--to=maz@kernel.org \
--cc=android-kvm@google.com \
--cc=catalin.marinas@arm.com \
--cc=joey.gouly@arm.com \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=oupton@kernel.org \
--cc=sebastianene@google.com \
--cc=suzuki.poulose@arm.com \
--cc=tabba@google.com \
--cc=vdonnefort@google.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