linux-kernel - Re: [PATCH v9 23/30] KVM: arm64: Context switch SME state for guests

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <5a053bb6-5052-4664-b0cb-f05d56d4679d@sirena.org.uk>
Date: Wed, 14 Jan 2026 17:27:53 +0000
From: Mark Brown <broonie@...nel.org>
To: Fuad Tabba <tabba@...gle.com>
Cc: Marc Zyngier <maz@...nel.org>, Joey Gouly <joey.gouly@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Will Deacon <will@...nel.org>, Paolo Bonzini <pbonzini@...hat.com>,
	Jonathan Corbet <corbet@....net>, Shuah Khan <shuah@...nel.org>,
	Oliver Upton <oupton@...nel.org>, Dave Martin <Dave.Martin@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ben Horgan <ben.horgan@....com>,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org,
	Peter Maydell <peter.maydell@...aro.org>,
	Eric Auger <eric.auger@...hat.com>
Subject: Re: [PATCH v9 23/30] KVM: arm64: Context switch SME state for guests

On Tue, Jan 13, 2026 at 02:24:56PM +0000, Fuad Tabba wrote:
> On Tue, 23 Dec 2025 at 01:23, Mark Brown <broonie@...nel.org> wrote:

> > +#define sme_cond_update_smcr_vq(val, reg)                      \
> > +       do {                                                    \
> > +               u64 __smcr = read_sysreg_s((reg));              \
> > +               u64 __new = __smcr & ~SMCR_ELx_LEN_MASK;        \
> > +               __new |= (val) & SMCR_ELx_LEN_MASK;             \

> Similar to what I pointed out in patch 15 [1], I think you need to
> preserve the other bits, since SMCR isn't just about the length.

This does preserve the existing bits?  It reads SMCR, masks out and then
replaces the length.

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)