From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 0BBBE2505D8 for ; Thu, 22 May 2025 07:55:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747900562; cv=none; b=WYs0rXD9YR3RBkXyJAHJb83VSz80KempKvJeseruhhINYfhkfzboq/QpGNQ6DmQ0qBHpN7JCCToTrACGnDCAmzOIlvIanx687P2Q70VwcvgPFulDqIqKmFdMNCoy6RN81RrtpUyiho55VIwPGpcjFRVSeQAf31vxR8CktDav8mw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747900562; c=relaxed/simple; bh=Y0bZYcvF9+9lkjpYmSvsSDY9TlAaGUiBHyHcnL0xFa0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fwDFTXpHcFY9eZ1u1+ObRFYUooHqCy5vUm/o0dpbvKn4g9dBDptMuad85+lJKi7UMwxPpgq3CClJoHUE6VRfpUaY7igHot6DwBd0eceFF+Z1ydwjqUqp7w4Mp+GXv0PXnVRdUtGI4FKb2tUp3MtoLlMYLAGxPBYnEDmqp/O395M= 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=dVCtjV+Q; arc=none smtp.client-ip=90.155.50.34 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="dVCtjV+Q" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=EousAwX9Gy0M7mH5mXeFXdv8f2FFIrnywnmZSDBYFhQ=; b=dVCtjV+QTuO0vMFK243xaj1Kye ypCyVNHWmPZldy6NwFeX4t3GiN+OnOU8hShrZZdhRcmIjZg210SlCn9m5mLD1+8KQ1CvY/hA6zHoD HcDD01KMxHbFrPdwkwMbI6tAJ4vqkDTDAnMAJJAkoyJENiPgUlJ8jFCWB2GwKfIwjen0ZqdpfqgCf t0E8f4+L/OXDXSGL2QLv8CV31KeJXuy2jXAdJKgDCjC9fyBM4otO1OLTHnbZQBBhE0ENqcLuiGYFn 1NVw6uoAHn2qyk2Pj9ov0VvnmNoBFhJWk9dGufflMQGpwC8xaTwi9ESQ3iIjrTnjQolYBr54Lk5CK u3Ku8lGw==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1uI0mP-00000005noY-3X9f; Thu, 22 May 2025 07:55:53 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 561CC30035E; Thu, 22 May 2025 09:55:53 +0200 (CEST) Date: Thu, 22 May 2025 09:55:53 +0200 From: Peter Zijlstra To: Thomas Gleixner Cc: Borislav Petkov , Ingo Molnar , "Ahmed S. Darwish" , Ard Biesheuvel , linux-kernel@vger.kernel.org, x86@kernel.org, Ard Biesheuvel , Linus Torvalds , Brian Gerst , "Kirill A. Shutemov" Subject: Re: [PATCH v4 1/6] x86/cpu: Use a new feature flag for 5 level paging Message-ID: <20250522075553.GG24938@noisy.programming.kicks-ass.net> References: <20250517091639.3807875-8-ardb+git@google.com> <20250517091639.3807875-9-ardb+git@google.com> <20250519094038.GIaCr8ltHvLBYjk8iI@fat_crate.local> <20250519131944.GCaCsv8A71vn21AB1W@fat_crate.local> <874ixernra.ffs@tglx> 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: <874ixernra.ffs@tglx> On Wed, May 21, 2025 at 05:23:37PM +0200, Thomas Gleixner wrote: > 4) Drivers having access to CPUID is just wrong. We've had issues > with that in the past because drivers evaluated CPUID themself and > missed that the core code had stuff disabled. I had this patch that read the module instructions and failed loading if they used 'fancy' instructions. Do you want me to revive that?