From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 6AB1C254AF3 for ; Wed, 5 Mar 2025 18:58:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741201097; cv=none; b=hlOvprqqGKhigwCB3IuJkvm2jQUKpUXgW9wQxaMz2BiDPZi9hHZ9FZXhFNJSL578++wot2s3+s8cIIcDeuGdXimkfVx6yLMYEDiQe+Bi0y/pfRiffsTkH76K3hFycxObzC+BO5J6ir+4CT8iBhEKWbHGHhD9tYWo61OU8driUPE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741201097; c=relaxed/simple; bh=RSntaKRcX6bb5OX0LcGpaXqGDiYfJFg4PmaXQ7xssMs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=US9UpTp8VYTPH35WaykJVNbEAHKKP1eo5TMsJIq9JOs//g5P99cLSIMfUJmnF1JN+MFGar1xyyGtbzZQSzoaEY2elFVwEsCxCDpdQvxf73YAouNV4BF7d0qPeIVdwEamiOoXmd/30tWq075Bd/LfhD5/Jj1UoruU7FmCIynhtT8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=shb/nAom; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Bq/9sah1; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="shb/nAom"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Bq/9sah1" Date: Wed, 5 Mar 2025 19:58:10 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1741201092; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RSntaKRcX6bb5OX0LcGpaXqGDiYfJFg4PmaXQ7xssMs=; b=shb/nAomBa1r0w31MtoWVdqGrxVaqYJjhXdvjWDo2YBc2f/bdFvNHbu5tPY154CN4GPP6z 4K/e+fBgmZuzDx88juCpAR/FBCWMRv94hBkLMysaHWal8CCed6n5pBvciJVdo6pAoCy18/ RgMpPT6pnz+L3ARi4rdvmDaHuNcFQbIAWnf5mebu5k1vuMHWDw8BXnyY0vHRHxSeRZk0Ya m8IKONDv4VapZARtyW/+dDMDFlesv3bF9Zq0nX5Qm+DFf65p9KartORjwoN6Sa7IBAtz0w CVgyHJXwFsy4TyTOrdUxm1v5rB2fYAGY1AOskQIcyBUIRWX4qcEyCrAa9zMNQg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1741201092; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RSntaKRcX6bb5OX0LcGpaXqGDiYfJFg4PmaXQ7xssMs=; b=Bq/9sah1YOs1Z+rX2TbAXViKuJRFACZgCMXswrHlauBuLhj3DYahHeC4xjroJCWIZAj9ek FL9FzU2chLM9qhBQ== From: "Ahmed S. Darwish" To: Andrew Cooper Cc: Borislav Petkov , Ingo Molnar , Dave Hansen , Thomas Gleixner , John Ogness , "H. Peter Anvin" , x86@kernel.org, x86-cpuid@lists.linux.dev, LKML Subject: Re: [PATCH v1 37/40] x86/cacheinfo: Extract out cache self-snoop checks Message-ID: References: <20250304085152.51092-1-darwi@linutronix.de> <20250304085152.51092-38-darwi@linutronix.de> <01367a6b-8eeb-417e-9a66-e7a64d518319@citrix.com> <6ba638d3-b3a3-410b-9761-0b3658e3215a@citrix.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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6ba638d3-b3a3-410b-9761-0b3658e3215a@citrix.com> On Wed, 05 Mar 2025, Andrew Cooper wrote: ... > It turns out not to be safe in cases where the underlying physical > memory changes from cacheable to unchangeable.  By skipping the WBINVD > as part of changing the memory type, you end up with spurious writebacks > at a later point when the memory is expected to be UC.  Apparently this > is a problem for CLX devices, hence the change in the SDM. ... > > CLX (Cascade Lake) != CXL (Compute eXpress Link). > > CXL is the new PCIe.  (So say the CXL consortium at least.) > Oh, sorry, you wrote "CLX devices" above, not CXL... Only thing my poor brain could come up with was CASCADELAKE_X :)