From: Will Deacon <will@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: kvm@vger.kernel.org, Suzuki K Poulose <suzuki.poulose@arm.com>,
David Brazdil <dbarzdil@google.com>,
James Morse <james.morse@arm.com>,
linux-arm-kernel@lists.infradead.org, kernel-team@android.com,
kvmarm@lists.cs.columbia.edu,
Julien Thierry <julien.thierry.kdev@gmail.com>
Subject: Re: [PATCH v2 0/2] KVM: arm64: Expose CSV3 to guests on running on Meltdown-safe HW
Date: Thu, 10 Dec 2020 13:53:41 +0000 [thread overview]
Message-ID: <20201210135341.GA10255@willie-the-truck> (raw)
In-Reply-To: <20201204183709.784533-1-maz@kernel.org>
On Fri, Dec 04, 2020 at 06:37:07PM +0000, Marc Zyngier wrote:
> Will recently pointed out that when running on big-little systems that
> are known not to be vulnerable to Metldown, guests are not presented
> with the CSV3 property if the physical HW include a core that doesn't
> have CSV3, despite being known to be safe (it is on the kpti_safe_list).
>
> Since this is valuable information that can be cheaply given to the
> guest, let's just do that. The scheme is the same as what we do for
> CSV2, allowing userspace to change the default setting if this doesn't
> advertise a safer setting than what the kernel thinks it is.
>
> * From v1:
> - Fix the clearing of ID_AA64PFR0_EL1.CSV3 on update from userspace
> - Actually store the userspace value
>
> Marc Zyngier (2):
> arm64: Make the Meltdown mitigation state available
> KVM: arm64: Advertise ID_AA64PFR0_EL1.CSV3=1 if the CPUs are
> Meltdown-safe
Acked-by: Will Deacon <will@kernel.org>
Will
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prev parent reply other threads:[~2020-12-10 13:55 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-04 18:37 [PATCH v2 0/2] KVM: arm64: Expose CSV3 to guests on running on Meltdown-safe HW Marc Zyngier
2020-12-04 18:37 ` [PATCH v2 1/2] arm64: Make the Meltdown mitigation state available Marc Zyngier
2020-12-04 18:37 ` [PATCH v2 2/2] KVM: arm64: Advertise ID_AA64PFR0_EL1.CSV3=1 if the CPUs are Meltdown-safe Marc Zyngier
2020-12-10 13:53 ` Will Deacon [this message]
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