From: Mark Brown <broonie@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Lorenzo Pieralisi <lpieralisi@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Sami Mujawar <Sami.Mujawar@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev
Subject: Re: [PATCH v2 08/14] arm64/cpufeature: Detect PE support for FEAT_NMI
Date: Mon, 5 Dec 2022 19:32:01 +0000 [thread overview]
Message-ID: <Y45HMaXwUcSHEplv@sirena.org.uk> (raw)
In-Reply-To: <86r0xdlodg.wl-maz@kernel.org>
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On Mon, Dec 05, 2022 at 06:03:07PM +0000, Marc Zyngier wrote:
> Mark Brown <broonie@kernel.org> wrote:
> > +#ifdef CONFIG_ARM64_NMI
> > + {
> > + .desc = "Non-maskable Interrupts",
> > + .capability = ARM64_HAS_NMI,
> > + .type = ARM64_CPUCAP_BOOT_CPU_FEATURE,
> PSEUDO_NMI uses ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE. What is the
> rational for using a different policy here?
I couldn't identify any issues that the kernel would have if the feature
was present in the hardware but unused so I didn't see the need to be
additionally restrictive. TBH I'm not 100% clear why the _STRICT is
there for pseudo NMIs, it seemed a bit out of scope for this series to
try to clean that up though.
> The whole thing is way too restrictive: KVM definitely needs to know
> that the feature exists, even if there is no use for it in the host
> kernel. There is no reason why guests shouldn't be able to use this
> even if the host doesn't care about it.
> Which means you need two properties: one that advertises the
> availability of the feature, and one that makes use of it in the
> kernel.
To be clear I think what you're looking for here is a capability that
omits the cross-check with pseudo NMIs rather than something that's
strictly checking the hardware (so ID register overrides will still
apply)? I've done that locally, my tree currently has capabilites
HAS_NMI and USES_NMI.
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next prev parent reply other threads:[~2022-12-05 19:33 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-12 15:16 [PATCH v2 00/14] arm64/nmi: Support for FEAT_NMI Mark Brown
2022-11-12 15:16 ` [PATCH v2 01/14] arm64/booting: Document boot requirements " Mark Brown
2022-11-12 15:16 ` [PATCH v2 02/14] arm64/sysreg: Add definition for ICC_NMIAR1_EL1 Mark Brown
2022-11-12 15:16 ` [PATCH v2 03/14] arm64/sysreg: Add definition of ISR_EL1 Mark Brown
2022-12-05 16:45 ` Marc Zyngier
2022-11-12 15:16 ` [PATCH v2 04/14] arm64/sysreg: Add definitions for immediate versions of MSR ALLINT Mark Brown
2022-12-05 16:38 ` Marc Zyngier
2022-12-05 17:11 ` Mark Brown
2022-12-07 19:18 ` Marc Zyngier
2022-12-07 19:42 ` Mark Brown
2022-11-12 15:16 ` [PATCH v2 05/14] arm64/asm: Introduce assembly macros for managing ALLINT Mark Brown
2022-12-05 17:29 ` Marc Zyngier
2022-12-05 18:24 ` Mark Brown
2022-12-07 19:14 ` Marc Zyngier
2022-11-12 15:17 ` [PATCH v2 06/14] arm64/hyp-stub: Enable access to ALLINT Mark Brown
2022-12-05 17:50 ` Marc Zyngier
2022-11-12 15:17 ` [PATCH v2 07/14] arm64/idreg: Add an override for FEAT_NMI Mark Brown
2022-11-12 15:17 ` [PATCH v2 08/14] arm64/cpufeature: Detect PE support " Mark Brown
2022-12-05 18:03 ` Marc Zyngier
2022-12-05 19:32 ` Mark Brown [this message]
2022-12-07 19:06 ` Marc Zyngier
2022-11-12 15:17 ` [PATCH v2 09/14] KVM: arm64: Hide FEAT_NMI from guests Mark Brown
2022-12-05 18:06 ` Marc Zyngier
2022-12-05 19:03 ` Mark Brown
2022-12-07 19:03 ` Marc Zyngier
2022-12-07 19:33 ` Mark Brown
2022-11-12 15:17 ` [PATCH v2 10/14] arm64/nmi: Manage masking for superpriority interrupts along with DAIF Mark Brown
2022-12-05 18:47 ` Marc Zyngier
2022-12-05 20:52 ` Mark Brown
2022-12-08 17:19 ` Lorenzo Pieralisi
2022-12-12 14:03 ` Mark Brown
2022-12-13 8:37 ` Lorenzo Pieralisi
2022-12-13 13:15 ` Mark Brown
2022-12-15 13:32 ` Marc Zyngier
2022-12-12 14:40 ` Mark Rutland
2022-12-15 13:21 ` Mark Brown
2022-11-12 15:17 ` [PATCH v2 11/14] arm64/irq: Document handling of FEAT_NMI in irqflags.h Mark Brown
2022-11-12 15:17 ` [PATCH v2 12/14] arm64/nmi: Add handling of superpriority interrupts as NMIs Mark Brown
2022-12-07 11:03 ` Marc Zyngier
2022-12-07 13:24 ` Mark Brown
2022-12-07 18:57 ` Marc Zyngier
2022-12-07 19:15 ` Mark Brown
2022-11-12 15:17 ` [PATCH v2 13/14] arm64/nmi: Add Kconfig for NMI Mark Brown
2022-11-12 15:17 ` [PATCH v2 14/14] irqchip/gic-v3: Implement FEAT_GICv3_NMI support Mark Brown
2022-12-07 15:20 ` Marc Zyngier
2022-12-02 18:42 ` [PATCH v2 00/14] arm64/nmi: Support for FEAT_NMI Marc Zyngier
2022-12-03 8:25 ` Lorenzo Pieralisi
2022-12-03 9:45 ` Marc Zyngier
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