From patchwork Fri Dec 15 08:43:01 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Boris Brezillon X-Patchwork-Id: 13494129 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A28C8C4332F for ; Fri, 15 Dec 2023 08:43:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=nymUuk9IPvwVZEzg/rGICu3jFEX8RaCZFuDystgguW4=; b=E9zbmpFDJQwVxF EfPxbeP6RVtNWZPwxv6rF6axRXwKnsbsNDU2ClvTd8+SsFUpUmUrhSQYx5D3acZty1v/TVHiJ5htg Hv+x7elnsw4PuLsCQYVV+rs9iq9SzYO3yh9G3fSXuFZUi049GWdE5umkG2YFln79LW4FDQN1kgzQ3 pF+vWX2DWLFDJF2qb72Xcvxfi4u2FpYKESBF8E3aU7yKlMMEMQr6DTCwttUHt3HBg/S+jZqsoDqFD D+GuukA2IU5EC4aBLkgOsHi6iPxNtmo01xAQTqXc2UP3ab3jb8pFl6e4km2qVLY8PXyWJCTvi0ZE6 bUan4KYsa5/a2qEcSwPw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rE3mr-002VfQ-0T; Fri, 15 Dec 2023 08:43:13 +0000 Received: from madrid.collaboradmins.com ([46.235.227.194]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rE3mo-002VeJ-0E for linux-arm-kernel@lists.infradead.org; Fri, 15 Dec 2023 08:43:11 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1702629784; bh=EEkU2hJy6nx0uwZjEoszE2dgSDUD/S/tzyjmu//yEgQ=; h=From:To:Cc:Subject:Date:From; b=jNB+/PlOKvBCNFgIZ83VBV2ewniDjF3ZAWlPYVPyRQz66hSzVF0/mu/KbNIxHMYAK V7F6ZhYGPp7uxsEKMfzW/GuTil9nxGPvPRGWEyFDIhKUPbUMG4oMcHA+GhbvMWsI9X Mj0dkrUn+6NTbK1crwKAhnmWqX3uEIiuG9gdaG7KldDUo61EnqWMTLkB/BE+QmYEyY UWVz9yjAiaTYFL4NJPvzAHZH1DXMw/5ZH3TuF3fD8xXSjspq1gjaErtZk+aNsqhkN5 HPHdNckJgbY5+mI0Q9ThQ/d6fk1n4ahocCHWVukPa+jRU4zfceNvW3+uiuEmrc7S+1 /ujwxNLqqdG9Q== Received: from localhost.localdomain (cola.collaboradmins.com [195.201.22.229]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by madrid.collaboradmins.com (Postfix) with ESMTPSA id EA99437813BC; Fri, 15 Dec 2023 08:43:03 +0000 (UTC) From: Boris Brezillon To: Joerg Roedel , iommu@lists.linux.dev, Will Deacon , Robin Murphy , linux-arm-kernel@lists.infradead.org Cc: Rob Clark , Gaurav Kohli , Steven Price , kernel@collabora.com, Jason Gunthorpe , Boris Brezillon Subject: [PATCH v4 1/2] iommu: Allow passing custom allocators to pgtable drivers Date: Fri, 15 Dec 2023 09:43:01 +0100 Message-ID: <20231215084302.2484163-1-boris.brezillon@collabora.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231215_004310_274880_C7095319 X-CRM114-Status: GOOD ( 19.43 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org This will be useful for GPU drivers who want to keep page tables in a pool so they can: - keep freed page tables in a free pool and speed-up upcoming page table allocations - batch page table allocation instead of allocating one page at a time - pre-reserve pages for page tables needed for map/unmap operations, to ensure map/unmap operations don't try to allocate memory in paths they're allowed to block or fail It might also be valuable for other aspects of GPU and similar use-cases, like fine-grained memory accounting and resource limiting. We will extend the Arm LPAE format to support custom allocators in a separate commit. Signed-off-by: Boris Brezillon Reviewed-by: Steven Price Reviewed-by: Robin Murphy Reviewed-by: Gaurav Kohli Tested-by: Gaurav Kohli --- v4: - Add Gaurav's R-b/T-b v3: - Add Robin R-b - Move caps definition around - Add extra constraints to the ->alloc() callback documentation v2: - Add Steven R-b - Expand on possible use-cases for custom allocators - Add a caps fields to io_pgtable_init_fns so we can simplify the check_custom_allocator() logic (Robin Murphy) --- drivers/iommu/io-pgtable.c | 23 +++++++++++++++++++++++ include/linux/io-pgtable.h | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 57 insertions(+) diff --git a/drivers/iommu/io-pgtable.c b/drivers/iommu/io-pgtable.c index b843fcd365d2..8841c1487f00 100644 --- a/drivers/iommu/io-pgtable.c +++ b/drivers/iommu/io-pgtable.c @@ -34,6 +34,26 @@ io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = { #endif }; +static int check_custom_allocator(enum io_pgtable_fmt fmt, + struct io_pgtable_cfg *cfg) +{ + /* No custom allocator, no need to check the format. */ + if (!cfg->alloc && !cfg->free) + return 0; + + /* When passing a custom allocator, both the alloc and free + * functions should be provided. + */ + if (!cfg->alloc || !cfg->free) + return -EINVAL; + + /* Make sure the format supports custom allocators. */ + if (io_pgtable_init_table[fmt]->caps & IO_PGTABLE_CAP_CUSTOM_ALLOCATOR) + return 0; + + return -EINVAL; +} + struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt, struct io_pgtable_cfg *cfg, void *cookie) @@ -44,6 +64,9 @@ struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt, if (fmt >= IO_PGTABLE_NUM_FMTS) return NULL; + if (check_custom_allocator(fmt, cfg)) + return NULL; + fns = io_pgtable_init_table[fmt]; if (!fns) return NULL; diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h index 25142a0e2fc2..86cf1f7ae389 100644 --- a/include/linux/io-pgtable.h +++ b/include/linux/io-pgtable.h @@ -100,6 +100,30 @@ struct io_pgtable_cfg { const struct iommu_flush_ops *tlb; struct device *iommu_dev; + /** + * @alloc: Custom page allocator. + * + * Optional hook used to allocate page tables. If this function is NULL, + * @free must be NULL too. + * + * Memory returned should be zeroed and suitable for dma_map_single() and + * virt_to_phys(). + * + * Not all formats support custom page allocators. Before considering + * passing a non-NULL value, make sure the chosen page format supports + * this feature. + */ + void *(*alloc)(void *cookie, size_t size, gfp_t gfp); + + /** + * @free: Custom page de-allocator. + * + * Optional hook used to free page tables allocated with the @alloc + * hook. Must be non-NULL if @alloc is not NULL, must be NULL + * otherwise. + */ + void (*free)(void *cookie, void *pages, size_t size); + /* Low-level data specific to the table format */ union { struct { @@ -241,16 +265,26 @@ io_pgtable_tlb_add_page(struct io_pgtable *iop, iop->cfg.tlb->tlb_add_page(gather, iova, granule, iop->cookie); } +/** + * enum io_pgtable_caps - IO page table backend capabilities. + */ +enum io_pgtable_caps { + /** @IO_PGTABLE_CAP_CUSTOM_ALLOCATOR: Backend accepts custom page table allocators. */ + IO_PGTABLE_CAP_CUSTOM_ALLOCATOR = BIT(0), +}; + /** * struct io_pgtable_init_fns - Alloc/free a set of page tables for a * particular format. * * @alloc: Allocate a set of page tables described by cfg. * @free: Free the page tables associated with iop. + * @caps: Combination of @io_pgtable_caps flags encoding the backend capabilities. */ struct io_pgtable_init_fns { struct io_pgtable *(*alloc)(struct io_pgtable_cfg *cfg, void *cookie); void (*free)(struct io_pgtable *iop); + u32 caps; }; extern struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s1_init_fns;