From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.alien8.de (mail.alien8.de [65.109.113.108]) (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 75AD627C842; Mon, 17 Nov 2025 14:49:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=65.109.113.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763390964; cv=none; b=R37c0pRPJY/SrwJxVm/pziFijeObSn4+V5M7ezwWpEOL5e5sJ5k1b4Shz2gVijWMXIzH3EcbmApUgUaxLM56RP+FZRUM4KXr1uXzK5gIDDEtgqqkeISkwio7dm4oM2E8UNvMrjP5x1RnKlETyibWDkQFGgERcLGgDWu+MQFzeyM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763390964; c=relaxed/simple; bh=S8BvsHeD0AeLcWf06BgwMrTgm+zr8WJUMblfMGsjpto=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qA0kDgaRptWHU95w+G+iWqZl3OHbAJ/lXRTgrGsxDfT4Tl1LWhCh0MKj5MPDWEw+yZD5d/aiIBgNYMOmBxX7n3EN+C+/b6rfwzjp0M7und1CLBAvOz3ymeS52To4yWtFjtJtY8N5Jc0vNY7JkdaoFVyd4PdvsEnLUHjd1IUlYOk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de; spf=pass smtp.mailfrom=alien8.de; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b=gCKmkY57; arc=none smtp.client-ip=65.109.113.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=alien8.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b="gCKmkY57" Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTP id C3D5740E022E; Mon, 17 Nov 2025 14:49:18 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at mail.alien8.de Authentication-Results: mail.alien8.de (amavisd-new); dkim=pass (4096-bit key) header.d=alien8.de Received: from mail.alien8.de ([127.0.0.1]) by localhost (mail.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id knQjdnLUgBcQ; Mon, 17 Nov 2025 14:49:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=alien8; t=1763390953; bh=A21fKw8PZFQqm3LnxJKKQT5CGTMxtIA9C3gw213t52I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gCKmkY57w0VpneojWpcBzvl0JPJC+qHcNCG+Gm+vDGV0adIlodnJqA1GR0VDYMMYX hjnENLTrJVPo4RkV12oERD8zRkFXhz47m8bE7lSzlhxVfCCuW5vBhtF1M9teMYuyep SX46pgXugc0ar5hOvZVY3lfY2vEiniNzPZjIqSXsSYJ7eGgVCJTcb/tXh2y7cgIdQy VYtVA7/plGcE3szkH9VJ2T6g6d7cpd+3FyMSvNxbALvLGnLKvum4hTcXSK05rB/D7L d+XYHyhY1L4OmPOmO/IYzTDgSlqelx2fbRx9PYpP8i8VkoBclm7wgqD1qoUdHNsBb0 rVYaXana5AwWFvPctjgeuDMqaZJYzBlorZfp3BzHWaXVDBNbLxDrzEBENuYPORM2Qu 6ReE613WGhBe7sADiAD2QINoEDlw8TKClQX9KyXb/X3dYPBs3R9v2H0p9nHLREJkhc OGJu/vrTNxiZ5PeXfAikl19YJnuTdXBtoAZtAz7wvDvnmnJgiJYjJ+tt0sN35fdYZl eWLqPVVbBVPishz8jUcxGs6J4JMWBdxKr9SgxAlV6ZNxjpy2SphJkqrKT7Vp1cpcCS hmJ2baEyGYHoLMplBNBgl2jJ1T07qz1HQdAuA1gp5LXpqTSpz1MydRFaYtKdqtiZ5Z cAnx5Agi6zzKRVxt8sXDh0rk= Received: from zn.tnic (pd9530da1.dip0.t-ipconnect.de [217.83.13.161]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with UTF8SMTPSA id EB0C740E01CD; Mon, 17 Nov 2025 14:48:46 +0000 (UTC) Date: Mon, 17 Nov 2025 15:48:40 +0100 From: Borislav Petkov To: Sohil Mehta Cc: x86@kernel.org, Dave Hansen , Thomas Gleixner , Ingo Molnar , Jonathan Corbet , "H . Peter Anvin" , Andy Lutomirski , Josh Poimboeuf , Peter Zijlstra , Ard Biesheuvel , "Kirill A . Shutemov" , Xin Li , David Woodhouse , Sean Christopherson , Rick Edgecombe , Vegard Nossum , Andrew Cooper , Randy Dunlap , Geert Uytterhoeven , Kees Cook , Tony Luck , Alexander Shishkin , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org Subject: Re: [PATCH v12 6/8] x86/traps: Communicate a LASS violation in #GP message Message-ID: <20251117144840.GIaRs1yNEYjdNF0SHu@fat_crate.local> References: <20251113224204.50391-1-sohil.mehta@intel.com> <20251113224204.50391-7-sohil.mehta@intel.com> 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=utf-8 Content-Disposition: inline In-Reply-To: <20251113224204.50391-7-sohil.mehta@intel.com> On Thu, Nov 13, 2025 at 02:42:02PM -0800, Sohil Mehta wrote: > + /* > + * If LASS is active, a NULL pointer dereference generates a #GP > + * instead of a #PF. > + */ I'm having trouble matching the comment... > + if (*addr < PAGE_SIZE) ... to the conditional. Aaaha: "With LASS active, any invalid access to user memory (including the first page frame) would be..." Why is the first page frame special to justify a special check? I must be missing something obvious here... Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette