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

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Message-ID: <86o6sk97mr.wl-maz@kernel.org>
Date: Tue, 12 Aug 2025 11:06:20 +0100
From: Marc Zyngier <maz@...nel.org>
To: Yeoreum Yun <yeoreum.yun@....com>
Cc: catalin.marinas@....com,
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Subject: Re: [PATCH v2 6/6] KVM: arm64: initialise SCTLR2_EL1 at __kvm_host_psci_cpu_entry()

On Mon, 11 Aug 2025 20:43:00 +0100,
Yeoreum Yun <yeoreum.yun@....com> wrote:
> 
> 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?

Yes, sorry, I got it mixed with HCRX_EL2. Patch #2 is where it should
land indeed.

	M.

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