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] [day] [month] [year] [list]

Message-ID: <CA+EHjTwMs6BzZwtcNjyZnxLb9Gs01B1RcDvo1RB-f2w98eMzFQ@mail.gmail.com>
Date: Thu, 15 Jan 2026 09:02:31 +0000
From: Fuad Tabba <tabba@...gle.com>
To: Mark Brown <broonie@...nel.org>
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 Wed, 14 Jan 2026 at 17:28, Mark Brown <broonie@...nel.org> wrote:
>
> 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.

You're right. Sorry for the noise.

Cheers,
/fuad