linux-kernel - Re: [PATCH 0/2] KVM: arm64: Control visibility of S1PIE related sysregs to userspace

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Message-ID: <86cym2x7cv.wl-maz@kernel.org>
Date: Wed, 21 Aug 2024 15:45:20 +0100
From: Marc Zyngier <maz@...nel.org>
To: Mark Brown <broonie@...nel.org>
Cc: Oliver Upton <oliver.upton@...ux.dev>,
	James Morse <james.morse@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Joey Gouly <joey.gouly@....com>,
	linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] KVM: arm64: Control visibility of S1PIE related sysregs to userspace

On Wed, 21 Aug 2024 15:01:54 +0100,
Mark Brown <broonie@...nel.org> wrote:
> 
> [1  <text/plain; us-ascii (7bit)>]
> On Wed, Aug 21, 2024 at 02:46:25PM +0100, Marc Zyngier wrote:
> > Mark Brown <broonie@...nel.org> wrote:
> 
> > > Mark Brown (2):
> > >       KVM: arm64: Hide TCR2_EL1 from userspace when disabled for guests
> > >       KVM: arm64: Hide S1PIE registers from userspace when disabled for guests
> 
> > If you are going to do this, please add it on top of [1], and handle
> > the corresponding EL2 registers.
> 
> OK.  To confirm, this is a desirable change?

Yes.

Ultimately, we need to revisit the way we deal with visibility, as
adding a myriad of helpers checking a combination of features doesn't
scale. That information should exist as a static table, just like the
trap bits.

But until then, that's probably the way.

	M.

-- 
Without deviation from the norm, progress is not possible.