From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 2965E1FD4 for ; Fri, 10 Jul 2026 01:00:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783645257; cv=none; b=TzpLrrrtKALfH0PMOGa35K7dwfHTDdVBrtaLp1RZ318MFfC9KQ2m5nNIYq/0k3QjdrpYLZUIJKR23/49F7xtwzwjZ93DAlBWPpAGFECbXAjwWY64bKAywuXgihQuRO8vm/v0ifuthooV3+RhD+NAyPeTREcCKasDfWlhoJieugM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783645257; c=relaxed/simple; bh=D7xsMNqxgtDor3HtGZK+8dics/aLyUyn/u2Y9V+fBsM=; h=Date:From:To:Cc:Message-ID:In-Reply-To:References:Subject: Mime-Version:Content-Type; b=ly8l4OgwK6md09gmbKBu7+JociqAISyfKWOUZXHIPwRUsRcK4mB86ag0b54WElqHZRyjQVemSwqsdsstGbVizEIVsPQoA1PCgw09j1ZX/V4my4PGLw8+2TKpa6eI6ZwmFxiep0I4Yc8oPzLma193KziV/al7G32M3REvU+2/DSk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TILADReo; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TILADReo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C3481F000E9; Fri, 10 Jul 2026 01:00:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783645255; bh=15pjR0K6DIp0dkq2ahqu5yknk8ig1dLWMV+egpv0BGA=; h=Date:From:To:Cc:In-Reply-To:References:Subject; b=TILADReoSVWfcGUW3MMzY4Ho55z3GtCLcI/vltyaTwKrf0NK2FfjrrrlsbJJpWV9x J1ta/Et+M/18+NpJkwAAmL/rfjEJrXy/yUvU07ODcBLbefb9hlmE9Tc4LEE+i75RR7 G0FNdEBtGAljo9zDmHLclxeP8fqpBbnXC6NqTqec2SmeeUi2xNy6VjUl7r0X5X975e ceJ+Z5CxTNv3QqggntfE3DPcwRozvJF3RdG5MabB+1Tjq99B9iWbpygvKPyThaQ97L wP1Ano32j5tKfqxdMv/TgPVDqhPH9QxX8wKlEjiEYCH/PfiMhHczDXHVICufgJpTzy EOWwp/tKcb7ZQ== Received: from phl-compute-12.internal (phl-compute-12.internal [10.202.2.52]) by mailfauth.phl.internal (Postfix) with ESMTP id 9EF3FF40068; Thu, 9 Jul 2026 21:00:54 -0400 (EDT) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-12.internal (MEProxy); Thu, 09 Jul 2026 21:00:54 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTGsYDfGD7sxNcvTONT2+aJJfxqyPBiaS3Mkdh2jbWQu+fCZIX0aLUIqA6NBOWA8Iy S1d44AqtcsvdKsUpMKxngGixr3adXdgl4ZOuaGBcCL5Atsk7rMj8Y0O+ujZos1nEh+55jA Ie6e3/gtSTxpbAKgKtrC6kwQFFaAICKOvt3RPzvwz0mlrlpz5g/f4kWYD2KuXpKR5O7bHZ yb8re0feSEfVGP7S9Y7KDiYnEJqR5E/fpU1i9KHC/VNkmkjNEBepIvCims16M22easzvDT 8Jts+UjL+EwmjLWu/CuntdiXBoWG2jry8Z+lhmCIbzTr/iY/hO79JgBTMA+jXTXoHF61iK 9kmeyU/EmT2StFDhfXhISwx2zyjq6HKDkTq5/yWad3UpsDizaxQjfScm9pGnIpcwzSMJd0 /N13x23xu2QPfEJkTCwxwKLp/UlwP66Kd9ynet1RdNHeVFPWzD/YgUEuf3raGleW9E6mJD eFtqzl6vMeJ4iHCrPl6FvznMULI0G19Fe7mxybeOnvVhy45kBAfYgKFNRCHOq2eCV7jC5F qFJe5+/P7L+i/Ce4Nk3q4TVyHURA9JgoM95KcBsm0mOEGqAlnJ0SIaIeEjTTP3hVhXMRGF +Z6kDdpTejQe/oNWFiV+HjZkjCC27bLjLabbloy8Qmy3sc8n2QGUH+W82apg X-ME-Proxy: Feedback-ID: i67ae4b3e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 9 Jul 2026 21:00:54 -0400 (EDT) Date: Thu, 09 Jul 2026 18:00:53 -0700 From: "Dan Williams (nvidia)" To: mhonap@nvidia.com, djbw@kernel.org, alex@shazbot.org, jgg@ziepe.ca, jic23@kernel.org, dave.jiang@intel.com, ankita@nvidia.com, alejandro.lucero-palau@amd.com, alison.schofield@intel.com, dave@stgolabs.net, dmatlack@google.com, gourry@gourry.net, ira.weiny@intel.com Cc: cjia@nvidia.com, kjaju@nvidia.com, vsethi@nvidia.com, zhiw@nvidia.com, mhonap@nvidia.com, kvm@vger.kernel.org, linux-cxl@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Message-ID: <6a50444528cae_3c589810050@djbw-dev.notmuch> In-Reply-To: <20260625165407.1769572-2-mhonap@nvidia.com> References: <20260625165407.1769572-1-mhonap@nvidia.com> <20260625165407.1769572-2-mhonap@nvidia.com> Subject: Re: [PATCH v3 01/11] cxl: Add cxl_get_hdm_info() helper for HDM decoder metadata 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-Transfer-Encoding: 7bit mhonap@ wrote: > From: Manish Honap > > cxl_probe_component_regs() finds the HDM decoder block during device > probe and caches its location, but does not record the decoder count > and does not expose the result outside drivers/cxl/. > > In-kernel cxl drivers (Type-2 accelerator drivers, vfio-cxl) need the > decoder count and the byte offset and size of the HDM block without > re-running the probe sequence. > > Record decoder_cnt in rmap->count when parsing the HDM capability in > cxl_probe_component_regs(), extend struct cxl_reg_map with a count > member, and add cxl_get_hdm_info() to return offset, size, and count > from the cached map. Export under the CXL namespace. > > Signed-off-by: Manish Honap > --- > drivers/cxl/core/pci.c | 33 +++++++++++++++++++++++++++++++++ > drivers/cxl/core/regs.c | 1 + > include/cxl/cxl.h | 4 ++++ > 3 files changed, 38 insertions(+) > > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > index 2bcd683aa286..c917608c16f9 100644 > --- a/drivers/cxl/core/pci.c > +++ b/drivers/cxl/core/pci.c > @@ -449,6 +449,39 @@ int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm, > } > EXPORT_SYMBOL_NS_GPL(cxl_hdm_decode_init, "CXL"); > > +/** > + * cxl_get_hdm_info - Get HDM decoder register block location and count > + * @cxlds: CXL device state (must have component regs enumerated via > + * cxl_probe_component_regs()) > + * @count: number of HDM decoders (from HDM Capability bits [3:0]) > + * @offset: byte offset of HDM decoder block within the component register BAR > + * @size: size in bytes of the HDM decoder block > + * > + * Exported for cxl drivers (in-kernel accelerator drivers, vfio-cxl) that > + * need HDM decoder metadata from the cached component-register map without > + * re-running the probe sequence. > + * > + * Return: 0 on success. -ENODEV if the HDM decoder block is not present. > + */ > +int cxl_get_hdm_info(struct cxl_dev_state *cxlds, u8 *count, > + resource_size_t *offset, resource_size_t *size) > +{ > + struct cxl_reg_map *hdm = &cxlds->reg_map.component_map.hdm_decoder; > + > + if (WARN_ON(!count || !offset || !size)) > + return -EINVAL; > + > + if (!hdm->valid) > + return -ENODEV; > + > + *count = hdm->count; > + *offset = hdm->offset; > + *size = hdm->size; > + > + return 0; > +} > +EXPORT_SYMBOL_NS_GPL(cxl_get_hdm_info, "CXL"); This is the same information that the CXL reset patches need to cache on the PCI device. Effectively this level of CXL information deserves to be as accessible as PCI BAR information, and should not need cxl_dev_state context to fetch it. So it would be good to depend on that rather than invent a new export mechanism.