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Date: Tue, 23 Apr 2024 07:10:23 -0700
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Subject: Re: [PATCH v4 2/5] cpu/speculation: Fix CPU mitigation defaults for !x86
From: Sean Christopherson <seanjc@google.com>
To: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org, 
	Linus Torvalds <torvalds@linux-foundation.org>, 
	Daniel Sneddon <daniel.sneddon@linux.intel.com>, 
	Pawan Gupta <pawan.kumar.gupta@linux.intel.com>, Thomas Gleixner <tglx@linutronix.de>, 
	Alexandre Chartre <alexandre.chartre@oracle.com>, 
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, Peter Zijlstra <peterz@infradead.org>, 
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Andrew Cooper <andrew.cooper3@citrix.com>, 
	Dave Hansen <dave.hansen@linux.intel.com>, Nikolay Borisov <nik.borisov@suse.com>, 
	KP Singh <kpsingh@kernel.org>, Waiman Long <longman@redhat.com>, Borislav Petkov <bp@alien8.de>, 
	Ingo Molnar <mingo@kernel.org>, Stephen Rothwell <sfr@canb.auug.org.au>, 
	Michael Ellerman <mpe@ellerman.id.au>, Geert Uytterhoeven <geert@linux-m68k.org>
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On Fri, Apr 19, 2024, Sean Christopherson wrote:
> On Fri, Apr 19, 2024, Josh Poimboeuf wrote:
> > CPU speculative execution mitigations were inadvertently disabled on
> > non-x86 arches by the following commit:
> > 
> >  f337a6a21e2f ("x86/cpu: Actually turn off mitigations by default for SPECULATION_MITIGATIONS=n")
> > 
> > Fix it by replacing CONFIG_SPECULATION_MITIGATIONS with a new generic
> > CONFIG_CPU_MITIGATIONS option and moving the x86-specific mitigations to
> > a separate menu which depends on CONFIG_CPU_MITIGATIONS.
> 
> Ah drat, I didn't check my mailbox until after Cc'ing Linus my own version[*].
> 
> I don't have a strong preference between the two, though I do think it's worth
> nothing that this will (obvioulsy) allow disabling mitigations at compile time
> on all architectures, which may or may not be desirable.
> 
> [*] https://lore.kernel.org/all/20240420000556.2645001-2-seanjc@google.com

Josh, when you get a chance, can you weigh in on my menu-preserving approach?

I want to get this resolved asap so that we're not scrambing on Friday again :-)