From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AC0271EC01F; Tue, 17 Dec 2024 11:50:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734436252; cv=none; b=ERARDJB9CP2yqmUKhqEsD5ljKuzZU1fr5j86+V66SUlyvoqvjKjkW0mO07XGpJ9i7Gie8XqB/f7nQVXhb15PUGz+WylhpA+A6dMjzbAP/k44M1sNSZmSU29zbboCdorvIDwSopD0ZoLu7imZjBuxirfFrsXp8BPQVE9czFPwkUQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734436252; c=relaxed/simple; bh=ViqCOSoR/5Oc43ls7HezXtbZDLOSU5TXHvdzQkiSbkM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=USaj1ag+kxsuZenwQLsACedkMytLBm2+reNVvIwbZJilHKQO2UrZdnVHAkMmkipHwc51BB/p9Exmh6r3BeBACaWXnrL3wLLgYkYXgRnBxK0TyyTNufb+M7O4lwuIZCItCuPezVzPisuWPSDn3dDPJsmIZz0UXGT8aojuWIrxnEI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=HKFedOop; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="HKFedOop" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=01JtgBOhDZPiaKNzWOsr8GiiDOYISUrtTSVb4wXML7s=; b=HKFedOopoXyWWMfVIGmf9A5iuG YIY6DShf7sgODfmUh5u2yM3+Sf743/L/BMhz0l+JlLoCANLME4dt57NjPKqPRh/DjhN6GyRKkeOSO uVYoS7LnzBNp2DlhWl9z0h9q7jY/nibW3oYgH2RRMHF6Fmw9/yCV5go6SRd089pBF87tK6e5rivmS KWSCgCsJpB0crtQOR5HvUmX2zbiipIybkyS2NaMAzjWZL3KOkp3sCZZX2fT88HEcM0mUdukL+rbTt 8EDOuVTZbTlYdr16j+gKXXLf7b39SurhI+9ZmHFWlJRizSrhxbXowA156iDJqZhZEQ9CSMgbwG3dC CP28oslA==; Received: from 77-249-17-89.cable.dynamic.v4.ziggo.nl ([77.249.17.89] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tNW64-000000054SO-1y0Z; Tue, 17 Dec 2024 11:50:40 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 0DCF730015F; Tue, 17 Dec 2024 12:50:40 +0100 (CET) Date: Tue, 17 Dec 2024 12:50:39 +0100 From: Peter Zijlstra To: Borislav Petkov Cc: Brendan Jackman , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/bugs: Add force_cpu_bug= cmdline param Message-ID: <20241217115039.GF11133@noisy.programming.kicks-ass.net> References: <20241119-force-cpu-bug-v1-1-2aa31c6c1ccf@google.com> <20241216171700.GIZ2BgjPerQ8jQlq8S@fat_crate.local> <20241217111752.GDZ2Fd4E4XX-w_t6eq@fat_crate.local> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241217111752.GDZ2Fd4E4XX-w_t6eq@fat_crate.local> On Tue, Dec 17, 2024 at 12:17:52PM +0100, Borislav Petkov wrote: > On Mon, Dec 16, 2024 at 06:58:24PM +0100, Brendan Jackman wrote: > > OK yeah, tainting definitely makes sense, I think that goes quite a > > long way to avoid bogus bug reports? > > It was my feeble attempt back then to leave enough breadcrumbs so that when > I see a bug report, I can say: "well, then don't do that then" and mark it as > invalid. :) > > > I will also update the docs to sound scarier. > > Right. Perhaps issue a pr_warn() for every bit set? People tend to not like WARN/ERR in their production logs much :-) > > So do you think we should allow setting arbitrary cpu features? That > > seems like a much bigger footgun. But then again, the difference > > between "big footgun" and "very big footgun" is not that important, > > either way it needs to be clear to users that this is a scary red > > button. > > Yeah, with your patch we're half-way there. Might as well do the whole thing > but again, this is only my opinion. Probably should hear what others have to > say first... Given I'm the one that did the retbleed=force thing (and other force options), I'm in favour.