From patchwork Thu Jul 13 15:23:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Petr Tesarik X-Patchwork-Id: 13312411 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B39BC0015E for ; Thu, 13 Jul 2023 15:27:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234837AbjGMP1g (ORCPT ); Thu, 13 Jul 2023 11:27:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234845AbjGMP1F (ORCPT ); Thu, 13 Jul 2023 11:27:05 -0400 Received: from frasgout11.his.huawei.com (unknown [14.137.139.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F000D273C; Thu, 13 Jul 2023 08:26:40 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.18.147.228]) by frasgout11.his.huawei.com (SkyGuard) with ESMTP id 4R1ypr1Sw4z9xGgv; Thu, 13 Jul 2023 23:15:32 +0800 (CST) Received: from A2101119013HW2.china.huawei.com (unknown [10.81.218.161]) by APP1 (Coremail) with SMTP id LxC2BwA3k94BF7BkxG6BBA--.7207S10; Thu, 13 Jul 2023 16:25:57 +0100 (CET) From: Petr Tesarik To: Stefano Stabellini , Russell King , Thomas Bogendoerfer , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)), "H. Peter Anvin" , Greg Kroah-Hartman , "Rafael J. Wysocki" , Juergen Gross , Oleksandr Tyshchenko , Christoph Hellwig , Marek Szyprowski , Robin Murphy , Petr Tesarik , Jonathan Corbet , Andy Shevchenko , Hans de Goede , James Seo , James Clark , Kees Cook , xen-devel@lists.xenproject.org (moderated list:XEN HYPERVISOR ARM), linux-arm-kernel@lists.infradead.org (moderated list:ARM PORT), linux-kernel@vger.kernel.org (open list), linux-mips@vger.kernel.org (open list:MIPS), iommu@lists.linux.dev (open list:XEN SWIOTLB SUBSYSTEM) Cc: Roberto Sassu , Kefeng Wang , petr@tesarici.cz Subject: [PATCH v4 8/8] swiotlb: search the software IO TLB only if a device makes use of it Date: Thu, 13 Jul 2023 17:23:19 +0200 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 X-CM-TRANSID: LxC2BwA3k94BF7BkxG6BBA--.7207S10 X-Coremail-Antispam: 1UD129KBjvJXoWxZF15Ww18ZF1fWr1UtFW7XFb_yoWrXF1DpF yUAFZ8Kayqqr97Cr92kF4UZ3Wagw4vkw43CryaqrnY9rn8JwnaqF1DKrWYv3s5Ar47ZF47 Xryj939Ykw17Xr7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUQl14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_JFI_Gr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26r4j6F4UM28EF7xvwVC2z280aVCY1x0267AKxVWxJr0_ GcWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2I x0cI8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8 JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2Y2 ka0xkIwI1lc7CjxVAaw2AFwI0_Jw0_GFylc7CjxVAKzI0EY4vE52x082I5MxAIw28IcxkI 7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxV Cjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWrXVW8Jr1lIxkGc2Ij64vIr41lIxAI cVC0I7IYx2IY67AKxVWUCVW8JwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJwCI42 IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280 aVCY1x0267AKxVWxJr0_GcJvcSsGvfC2KfnxnUUI43ZEXa7VUjgAw3UUUUU== X-CM-SenderInfo: hshw23xhvd2x3n6k3tpzhluzxrxghudrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org From: Petr Tesarik Skip searching the software IO TLB if a device has never used it, making sure these devices are not affected by the introduction of multiple IO TLB memory pools. Additional memory barrier is required to ensure that the new value of the flag is visible to other CPUs after mapping a new bounce buffer. For efficiency, the flag check should be inlined, and then the memory barrier must be moved to is_swiotlb_buffer(). However, it can replace the existing barrier in swiotlb_find_pool(), because all callers use is_swiotlb_buffer() first to verify that the buffer address belongs to the software IO TLB. Signed-off-by: Petr Tesarik --- include/linux/device.h | 2 ++ include/linux/swiotlb.h | 6 +++++- kernel/dma/swiotlb.c | 14 ++++++-------- 3 files changed, 13 insertions(+), 9 deletions(-) diff --git a/include/linux/device.h b/include/linux/device.h index 549b0a62455c..86871d628648 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -628,6 +628,7 @@ struct device_physical_location { * @dma_io_tlb_mem: Software IO TLB allocator. Not for driver use. * @dma_io_tlb_pools: List of transient swiotlb memory pools. * @dma_io_tlb_lock: Protects changes to the list of active pools. + * @dma_uses_io_tlb: %true if device has used the software IO TLB. * @archdata: For arch-specific additions. * @of_node: Associated device tree node. * @fwnode: Associated device node supplied by platform firmware. @@ -735,6 +736,7 @@ struct device { struct io_tlb_mem *dma_io_tlb_mem; struct list_head dma_io_tlb_pools; spinlock_t dma_io_tlb_lock; + bool dma_uses_io_tlb; #endif /* arch specific additions */ struct dev_archdata archdata; diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 06fd94de1cd8..8069cb62c893 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -150,7 +150,11 @@ struct io_tlb_pool *swiotlb_find_pool(struct device *dev, phys_addr_t paddr); */ static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr) { - return dev->dma_io_tlb_mem && + /* Pairs with smp_wmb() in swiotlb_find_slots() and + * swiotlb_dyn_alloc(), which modify the RCU lists. + */ + smp_rmb(); + return dev->dma_uses_io_tlb && !!swiotlb_find_pool(dev, paddr); } diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 9c66ec2c47dd..854d139ddcb7 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -706,7 +706,7 @@ static void swiotlb_dyn_alloc(struct work_struct *work) add_mem_pool(mem, pool); - /* Pairs with smp_rmb() in swiotlb_find_pool(). */ + /* Pairs with smp_rmb() in is_swiotlb_buffer(). */ smp_wmb(); } @@ -734,6 +734,7 @@ void swiotlb_dev_init(struct device *dev) dev->dma_io_tlb_mem = &io_tlb_default_mem; INIT_LIST_HEAD(&dev->dma_io_tlb_pools); spin_lock_init(&dev->dma_io_tlb_lock); + dev->dma_uses_io_tlb = false; } /** @@ -751,11 +752,6 @@ struct io_tlb_pool *swiotlb_find_pool(struct device *dev, phys_addr_t paddr) struct io_tlb_mem *mem = dev->dma_io_tlb_mem; struct io_tlb_pool *pool; - /* Pairs with smp_wmb() in swiotlb_find_slots() and - * swiotlb_dyn_alloc(), which modify the RCU lists. - */ - smp_rmb(); - rcu_read_lock(); list_for_each_entry_rcu(pool, &mem->pools, node) { if (paddr >= pool->start && paddr < pool->end) @@ -1128,9 +1124,11 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr, list_add_rcu(&pool->node, &dev->dma_io_tlb_pools); spin_unlock_irqrestore(&dev->dma_io_tlb_lock, flags); - /* Pairs with smp_rmb() in swiotlb_find_pool(). */ - smp_wmb(); found: + dev->dma_uses_io_tlb = true; + /* Pairs with smp_rmb() in is_swiotlb_buffer() */ + smp_wmb(); + *retpool = pool; return index; }