From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 96F931FF7A1; Mon, 7 Apr 2025 15:36:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744040163; cv=none; b=Jza3WVPX1TKazNWs5uusV0bKYBg3FyI2dl6Iisg0oG1jmM1BoLorBeqk7GXjXNG1TzCyVLFMpJwEPOVKc+XUqE05vGo6iFebAy4no/rKb0AbPPt2eWwzwXzF9rj6ojg30H2R6q3FzNNnx0wvIJNqkOdvQviiPN3VGFOkcFwHTu4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744040163; c=relaxed/simple; bh=vxoIfOH3hv+8JcQzJTe2JCQ2H+ulfHSIZy2SW/nfLss=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=n5tHFBMBSbaLYf+y8ZvweDpgSQwGimjFs4NKG9oSNQbEiduyJGEZhNXtr/sFptyJUxk3b9jE339qI6BwMPa1FkbZ9Kob3QEvAsFrDbRX1YlUlgoT4L6ZqwK+hYsJWqvGM7sKsJs266+vJReUzqgPeOS67XIGji4QLmZ+HKmcb5U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hqhfbebs; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hqhfbebs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5740CC4CEDD; Mon, 7 Apr 2025 15:35:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744040163; bh=vxoIfOH3hv+8JcQzJTe2JCQ2H+ulfHSIZy2SW/nfLss=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hqhfbebs3x7d/GCPZcnQpCNFvIZ976SbyTsrHJ1Y/fneZ6Ex5mUrI2YzWo5ApBnFg hvaIToBRaRC1n0Sa1cxX2tu6tXj9PLKhaoYdAYLSTxmFbTyNTDCA5DfjGOw/uckaxS KkBf9o/Af5iXoNGTT4yOlYpvtnX/M5ON8RDEKI5MzAcmWdkNRcMakKFjpNbJgZ0rXh FnMLV0DdAQfSPLvGF65KBxWj8PkXK5IyrG/X/484QsEpcfpM9TahsgXAhAz8vP+VP3 HF22onlmXjZQouFmEW1f9BNwgbDHvhliKJgC16bGB3JM+aYwXfCeYLq0HW8NIKdnNk wGNJ2WDKCXTeA== Date: Mon, 7 Apr 2025 17:35:56 +0200 From: Niklas Cassel To: Jerome Brunet Cc: Manivannan Sadhasivam , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Kishon Vijay Abraham I , Bjorn Helgaas , Lorenzo Pieralisi , Jon Mason , Dave Jiang , Allen Hubbe , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , Marek Vasut , Yoshihiro Shimoda , Yuya Hamamachi , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, ntb@lists.linux.dev, linux-nvme@lists.infradead.org Subject: Re: [PATCH v3 2/3] PCI: endpoint: improve fixed_size bar handling when allocating space Message-ID: References: <20250407-pci-ep-size-alignment-v3-0-865878e68cc8@baylibre.com> <20250407-pci-ep-size-alignment-v3-2-865878e68cc8@baylibre.com> Precedence: bulk X-Mailing-List: linux-pci@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: <20250407-pci-ep-size-alignment-v3-2-865878e68cc8@baylibre.com> Hello Jerome, On Mon, Apr 07, 2025 at 04:39:08PM +0200, Jerome Brunet wrote: > When trying to allocate space for an endpoint function on a BAR with a > fixed size, the size saved in the 'struct pci_epf_bar' should be the fixed > size. This is expected by pci_epc_set_bar(). > > However, if the fixed_size is smaller that the alignment, the size saved > in the 'struct pci_epf_bar' matches the alignment and it is a problem for > pci_epc_set_bar(). > > To solve this, continue to allocate space that match the iATU alignment > requirement but save the size that matches what is present in the BAR. > > Fixes: 2a9a801620ef ("PCI: endpoint: Add support to specify alignment for buffers allocated to BARs") > Signed-off-by: Jerome Brunet > --- > drivers/pci/endpoint/pci-epf-core.c | 25 +++++++++++++++++-------- > 1 file changed, 17 insertions(+), 8 deletions(-) > > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c > index b7deb0ee1760b23a24f49abf3baf53ea2f273476..fb902b751e1c965c902c5199d57969ae0a757c2e 100644 > --- a/drivers/pci/endpoint/pci-epf-core.c > +++ b/drivers/pci/endpoint/pci-epf-core.c > @@ -225,6 +225,7 @@ void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar, > struct device *dev; > struct pci_epf_bar *epf_bar; > struct pci_epc *epc; > + size_t size; > > if (!addr) > return; > @@ -237,9 +238,12 @@ void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar, > epf_bar = epf->sec_epc_bar; > } > > + size = epf_bar[bar].size; > + if (epc_features->align) > + size = ALIGN(size, epc_features->align); Personally, I think that you should just save the aligned_size / mem_size / backing_mem_size as a new struct member, as that avoids the risk that someone later modifies pci_epf_alloc_space() but forgets to update pci_epf_free_space() accordingly. But I will leave the decision to the PCI endpoint maintainers. Kind regards, Niklas > + > dev = epc->dev.parent; > - dma_free_coherent(dev, epf_bar[bar].size, addr, > - epf_bar[bar].phys_addr); > + dma_free_coherent(dev, size, addr, epf_bar[bar].phys_addr); > > epf_bar[bar].phys_addr = 0; > epf_bar[bar].addr = NULL; > @@ -266,7 +270,7 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, > enum pci_epc_interface_type type) > { > u64 bar_fixed_size = epc_features->bar[bar].fixed_size; > - size_t align = epc_features->align; > + size_t aligned_size, align = epc_features->align; > struct pci_epf_bar *epf_bar; > dma_addr_t phys_addr; > struct pci_epc *epc; > @@ -287,12 +291,17 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, > return NULL; > } > size = bar_fixed_size; > + } else { > + /* BAR size must be power of two */ > + size = roundup_pow_of_two(size); > } > > - if (align) > - size = ALIGN(size, align); > - else > - size = roundup_pow_of_two(size); > + /* > + * Allocate enough memory to accommodate the iATU alignment requirement. > + * In most cases, this will be the same as .size but it might be different > + * if, for example, the fixed size of a BAR is smaller than align > + */ > + aligned_size = align ? ALIGN(size, align) : size; > > if (type == PRIMARY_INTERFACE) { > epc = epf->epc; > @@ -303,7 +312,7 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, > } > > dev = epc->dev.parent; > - space = dma_alloc_coherent(dev, size, &phys_addr, GFP_KERNEL); > + space = dma_alloc_coherent(dev, aligned_size, &phys_addr, GFP_KERNEL); > if (!space) { > dev_err(dev, "failed to allocate mem space\n"); > return NULL; > > -- > 2.47.2 >