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From: Christoph Hellwig <hch@lst.de>
To: "Petr Tesařík" <petr@tesarici.cz>
Cc: Christoph Hellwig <hch@lst.de>,
	Petr Tesarik <petrtesarik@huaweicloud.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Juergen Gross <jgross@suse.com>,
	Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Petr Tesarik <petr.tesarik.ext@huawei.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Hans de Goede <hdegoede@redhat.com>, James Seo <james@equiv.tech>,
	James Clark <james.clark@arm.com>,
	Kees Cook <keescook@chromium.org>,
	"moderated list:XEN HYPERVISOR ARM"
	<xen-devel@lists.xenproject.org>,
	"moderated list:ARM PORT" <linux-arm-kernel@lists.infradead.org>,
	open list <linux-kernel@vger.kernel.org>,
	"open list:MIPS" <linux-mips@vger.kernel.org>,
	"open list:XEN SWIOTLB SUBSYSTEM" <iommu@lists.linux.dev>,
	Roberto Sassu <roberto.sassu@huaweicloud.com>,
	Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: Re: [PATCH v4 8/8] swiotlb: search the software IO TLB only if a device makes use of it
Date: Thu, 20 Jul 2023 10:22:42 +0200	[thread overview]
Message-ID: <20230720082242.GA6932@lst.de> (raw)
In-Reply-To: <20230720100238.58f11c06@meshulam.tesarici.cz>

On Thu, Jul 20, 2023 at 10:02:38AM +0200, Petr Tesařík wrote:
> On Thu, 20 Jul 2023 08:47:44 +0200
> Christoph Hellwig <hch@lst.de> wrote:
> 
> > Any reason this can't just do a list_empty_careful on the list
> > instead of adding yet another field that grows struct device?
> 
> On which list?

dev->dma_io_tlb_mem->pools?

> 
> The dma_io_tlb_pools list only contains transient pools, but a device
> may use bounce buffers from a regular pool.

Oh, true.

> The dma_io_tlb_mem.pools list will always be non-empty, unless the
> system runs without SWIOTLB.
> 
> On a system which does have a SWIOTLB, the flag allows to differentiate
> between devices that actually use bounce buffers and devices that do
> not (e.g. because they do not have any addressing limitations).

Ok.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: "Petr Tesařík" <petr@tesarici.cz>
Cc: Christoph Hellwig <hch@lst.de>,
	Petr Tesarik <petrtesarik@huaweicloud.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Juergen Gross <jgross@suse.com>,
	Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Petr Tesarik <petr.tesarik.ext@huawei.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Hans de Goede <hdegoede@redhat.com>, James Seo <james@equiv.tech>,
	James Clark <james.clark@arm.com>,
	Kees Cook <keescook@chromium.org>,
	"moderated list:XEN HYPERVISOR ARM"
	<xen-devel@lists.xenproject.org>,
	"moderated list:ARM PORT" <linux-arm-kernel@lists.infradead.org>,
	open list <linux-kernel@vger.kernel.org>,
	"open list:MIPS" <linux-mips@vger.kernel.org>,
	"open list:XEN SWIOTLB SUBSYSTEM" <iommu@lists.linux.dev>,
	Roberto Sassu <roberto.sassu@huaweicloud.com>,
	Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: Re: [PATCH v4 8/8] swiotlb: search the software IO TLB only if a device makes use of it
Date: Thu, 20 Jul 2023 10:22:42 +0200	[thread overview]
Message-ID: <20230720082242.GA6932@lst.de> (raw)
In-Reply-To: <20230720100238.58f11c06@meshulam.tesarici.cz>

On Thu, Jul 20, 2023 at 10:02:38AM +0200, Petr Tesařík wrote:
> On Thu, 20 Jul 2023 08:47:44 +0200
> Christoph Hellwig <hch@lst.de> wrote:
> 
> > Any reason this can't just do a list_empty_careful on the list
> > instead of adding yet another field that grows struct device?
> 
> On which list?

dev->dma_io_tlb_mem->pools?

> 
> The dma_io_tlb_pools list only contains transient pools, but a device
> may use bounce buffers from a regular pool.

Oh, true.

> The dma_io_tlb_mem.pools list will always be non-empty, unless the
> system runs without SWIOTLB.
> 
> On a system which does have a SWIOTLB, the flag allows to differentiate
> between devices that actually use bounce buffers and devices that do
> not (e.g. because they do not have any addressing limitations).

Ok.

_______________________________________________
linux-arm-kernel mailing list
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2023-07-20  8:22 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-13 15:23 [PATCH v4 0/8] Allow dynamic allocation of software IO TLB bounce buffers Petr Tesarik
2023-07-13 15:23 ` Petr Tesarik
2023-07-13 15:23 ` [PATCH v4 1/8] swiotlb: make io_tlb_default_mem local to swiotlb.c Petr Tesarik
2023-07-13 15:23   ` Petr Tesarik
2023-07-17  6:06   ` Philippe Mathieu-Daudé
2023-07-17  6:06     ` Philippe Mathieu-Daudé
2023-07-17 10:17     ` Petr Tesařík
2023-07-17 10:17       ` Petr Tesařík
2023-07-20  6:37   ` Christoph Hellwig
2023-07-20  6:37     ` Christoph Hellwig
2023-07-20  7:54     ` Petr Tesařík
2023-07-20  7:54       ` Petr Tesařík
2023-07-13 15:23 ` [PATCH v4 2/8] swiotlb: add documentation and rename swiotlb_do_find_slots() Petr Tesarik
2023-07-13 15:23   ` Petr Tesarik
2023-07-20  6:38   ` Christoph Hellwig
2023-07-20  6:38     ` Christoph Hellwig
2023-07-20  7:56     ` Petr Tesařík
2023-07-20  7:56       ` Petr Tesařík
2023-07-20  8:01       ` Christoph Hellwig
2023-07-20  8:01         ` Christoph Hellwig
2023-07-20  8:14         ` Petr Tesařík
2023-07-20  8:14           ` Petr Tesařík
2023-07-13 15:23 ` [PATCH v4 3/8] swiotlb: separate memory pool data from other allocator data Petr Tesarik
2023-07-13 15:23   ` Petr Tesarik
2023-07-13 17:53   ` Petr Tesařík
2023-07-13 17:53     ` Petr Tesařík
2023-07-13 15:23 ` [PATCH v4 4/8] swiotlb: add a flag whether a SWIOTLB is allowed to grow Petr Tesarik
2023-07-13 15:23   ` Petr Tesarik
2023-07-13 15:23 ` [PATCH v4 5/8] swiotlb: if swiotlb is full, fall back to a transient memory pool Petr Tesarik
2023-07-13 15:23   ` Petr Tesarik
2023-07-13 15:23 ` [PATCH v4 6/8] swiotlb: determine potential physical address limit Petr Tesarik
2023-07-13 15:23   ` Petr Tesarik
2023-07-13 15:23 ` [PATCH v4 7/8] swiotlb: allocate a new memory pool when existing pools are full Petr Tesarik
2023-07-13 15:23   ` Petr Tesarik
2023-07-13 15:23 ` [PATCH v4 8/8] swiotlb: search the software IO TLB only if a device makes use of it Petr Tesarik
2023-07-13 15:23   ` Petr Tesarik
2023-07-20  6:47   ` Christoph Hellwig
2023-07-20  6:47     ` Christoph Hellwig
2023-07-20  8:02     ` Petr Tesařík
2023-07-20  8:02       ` Petr Tesařík
2023-07-20  8:22       ` Christoph Hellwig [this message]
2023-07-20  8:22         ` Christoph Hellwig
2023-07-20  6:52 ` [PATCH v4 0/8] Allow dynamic allocation of software IO TLB bounce buffers Christoph Hellwig
2023-07-20  6:52   ` Christoph Hellwig
2023-07-20  8:13   ` Petr Tesařík
2023-07-20  8:13     ` Petr Tesařík
2023-07-20  8:23     ` Christoph Hellwig
2023-07-20  8:23       ` Christoph Hellwig

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