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Sender: Ingo Molnar <mingo.kernel.org@gmail.com>
Date: Fri, 12 Apr 2024 12:07:49 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>, x86@kernel.org,
	linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Daniel Sneddon <daniel.sneddon@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>,
	Sean Christopherson <seanjc@google.com>,
	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>
Subject: Re: [PATCH 5/7] x86/bugs: Only harden syscalls when needed
Message-ID: <ZhkH9aFKw+Y1utPV@gmail.com>
References: <cover.1712813475.git.jpoimboe@kernel.org>
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* Josh Poimboeuf <jpoimboe@kernel.org> wrote:

> > [...]
> > > @@ -1720,6 +1744,7 @@ static void __init spectre_v2_select_mitigation(void)
> > >  
> > >  	case SPECTRE_V2_CMD_RETPOLINE_LFENCE:
> > >  		pr_err(SPECTRE_V2_LFENCE_MSG);
> > > +		setup_clear_cpu_cap(X86_FEATURE_INDIRECT_SAFE);
> > 
> > I don't know if it intentional, this seems to be the duplicate of
> > X86_FEATURE_INDIRECT_SAFE clear later in SPECTRE_V2_LFENCE mode. Also it
> > seems a bit odd to do this here in SPECTRE_V2_CMD handling.
> 
> Yeah, I accidentally left that in from an earlier implementation.  It's 
> harmless but I'll clean that up too with a new patch unless Ingo wants to 
> remove that line.

Lemme remove it entirely from x86/urgent, so that you can submit an updated 
patch with all feedback included.

In addition to the above line, Pawan's suggestion of doing it in C via 
cpu_feature_enabled() looks quite a bit simpler and easier to read & argue 
about, right?

Thanks,

	Ingo