linux-kernel - Re: [PATCH v2 6/6] KVM: arm64: initialise SCTLR2_EL1 at __kvm_host_psci_cpu

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Message-ID: <aJpHxLgmy5A/YD7V@e129823.arm.com>
Date: Mon, 11 Aug 2025 20:43:00 +0100
From: Yeoreum Yun <yeoreum.yun@....com>
To: Marc Zyngier <maz@...nel.org>
Cc: catalin.marinas@....com, will@...nel.org, broonie@...nel.org,
	oliver.upton@...ux.dev, anshuman.khandual@....com, robh@...nel.org,
	james.morse@....com, mark.rutland@....com, joey.gouly@....com,
	ry111@...111.site, Dave.Martin@....com, ahmed.genidi@....com,
	kevin.brodsky@....com, scott@...amperecomputing.com, mbenes@...e.cz,
	james.clark@...aro.org, frederic@...nel.org, rafael@...nel.org,
	pavel@...nel.org, ryan.roberts@....com, suzuki.poulose@....com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, kvmarm@...ts.linux.dev
Subject: Re: [PATCH v2 6/6] KVM: arm64: initialise SCTLR2_EL1 at
 __kvm_host_psci_cpu_entry()

Hi Marc,

> > initialise SCTLR2_EL1 at __kvm_host_psci_cpu_entry().
>
> Same comment, I don't think this is an acceptable commit message.
> Please ask for help if you don't feel confident writing it (I'm sure
> some of your colleagues will be happy to help).

Okay. I'll rewrite the commit message

> > @@ -219,6 +220,8 @@ asmlinkage void __noreturn __kvm_host_psci_cpu_entry(bool is_cpu_on)
> >  		release_boot_args(boot_args);
> >
> >  	write_sysreg_el1(INIT_SCTLR_EL1_MMU_OFF, SYS_SCTLR);
> > +	if (alternative_has_cap_unlikely(ARM64_HAS_SCTLR2))
> > +		write_sysreg_el1(INIT_SCTLR2_EL1, SYS_SCTLR2);
> >  	write_sysreg(INIT_PSTATE_EL1, SPSR_EL2);
> >
> >  	__host_enter(host_ctxt);
>
> This needs to be folded into patch #1.
>
> Otherwise, there is a window of patches where the kernel will not
> survive CPU hotplug when booted in protected mode.

Do you mean fold this patch into patch #2 where initialise
SCTLR2_ELx?

Thanks.

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

--
Sincerely,
Yeoreum Yun