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([2404:f801:9000:18:efec::754]) by smtp.gmail.com with ESMTPSA id b17-20020a056a000a9100b004e1b7cdb8fdsm3751492pfl.70.2022.02.25.06.28.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Feb 2022 06:29:02 -0800 (PST) Message-ID: Date: Fri, 25 Feb 2022 22:28:54 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.0 Subject: Re: [PATCH V2 1/2] Swiotlb: Add swiotlb_alloc_from_low_pages switch Content-Language: en-US From: Tianyu Lan To: Christoph Hellwig Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, hch@infradead.org, m.szyprowski@samsung.com, robin.murphy@arm.com, michael.h.kelley@microsoft.com, Tianyu Lan , iommu@lists.linux-foundation.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, vkuznets@redhat.com, brijesh.singh@amd.com, konrad.wilk@oracle.com, parri.andrea@gmail.com, thomas.lendacky@amd.com, "krish.sadhukhan@oracle.com" , "kirill.shutemov@linux.intel.com" References: <20220209122302.213882-1-ltykernel@gmail.com> <20220209122302.213882-2-ltykernel@gmail.com> <20220214081919.GA18337@lst.de> <4f433f07-05be-f81f-43e8-55c3f1af23b3@gmail.com> <20220214135834.GA30150@lst.de> <8d052867-ccff-f00f-7c89-cc26a4bfa347@gmail.com> <23f4a64d-5977-1816-8faa-fe7691ace2ff@gmail.com> <20220222080543.GA5412@lst.de> <00112505-4999-ac41-877e-49c4cc45312e@gmail.com> <20220222160039.GA13380@lst.de> <40f91949-58fa-4be2-5b01-ea34dda58670@gmail.com> In-Reply-To: <40f91949-58fa-4be2-5b01-ea34dda58670@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/23/2022 5:46 PM, Tianyu Lan wrote: > > > On 2/23/2022 12:00 AM, Christoph Hellwig wrote: >> On Tue, Feb 22, 2022 at 11:07:19PM +0800, Tianyu Lan wrote: >>> Thanks for your comment. That means we need to expose an >>> swiotlb_device_init() interface to allocate bounce buffer and initialize >>> io tlb mem entry. DMA API Current  rmem_swiotlb_device_init() only works >>> for platform with device tree. The new API should be called in the bus >>> driver or new DMA API. Could you check whether this is a right way >>> before >>> we start the work. >> >> Do these VMs use ACPI?  We'd probably really want some kind of higher >> level configuration and not have the drivers request it themselves. > > Yes, Hyper-V isolation VM uses ACPI. Devices are enumerated via vmbus > host and there is no child device information in ACPI table. The host > driver seems to be the right place to call new API. Hi Christoph: One more perspective is that one device may have multiple queues and each queues should have independent swiotlb bounce buffer to avoid spin lock overhead. The number of queues is only available in the device driver. This means new API needs to be called in the device driver according to queue number. 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([2404:f801:9000:18:efec::754]) by smtp.gmail.com with ESMTPSA id b17-20020a056a000a9100b004e1b7cdb8fdsm3751492pfl.70.2022.02.25.06.28.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Feb 2022 06:29:02 -0800 (PST) Message-ID: Date: Fri, 25 Feb 2022 22:28:54 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.0 Subject: Re: [PATCH V2 1/2] Swiotlb: Add swiotlb_alloc_from_low_pages switch Content-Language: en-US From: Tianyu Lan To: Christoph Hellwig References: <20220209122302.213882-1-ltykernel@gmail.com> <20220209122302.213882-2-ltykernel@gmail.com> <20220214081919.GA18337@lst.de> <4f433f07-05be-f81f-43e8-55c3f1af23b3@gmail.com> <20220214135834.GA30150@lst.de> <8d052867-ccff-f00f-7c89-cc26a4bfa347@gmail.com> <23f4a64d-5977-1816-8faa-fe7691ace2ff@gmail.com> <20220222080543.GA5412@lst.de> <00112505-4999-ac41-877e-49c4cc45312e@gmail.com> <20220222160039.GA13380@lst.de> <40f91949-58fa-4be2-5b01-ea34dda58670@gmail.com> In-Reply-To: <40f91949-58fa-4be2-5b01-ea34dda58670@gmail.com> Cc: linux-hyperv@vger.kernel.org, brijesh.singh@amd.com, dave.hansen@linux.intel.com, hpa@zytor.com, kys@microsoft.com, hch@infradead.org, wei.liu@kernel.org, sthemmin@microsoft.com, x86@kernel.org, decui@microsoft.com, michael.h.kelley@microsoft.com, mingo@redhat.com, parri.andrea@gmail.com, thomas.lendacky@amd.com, Tianyu Lan , konrad.wilk@oracle.com, haiyangz@microsoft.com, bp@alien8.de, "krish.sadhukhan@oracle.com" , tglx@linutronix.de, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, vkuznets@redhat.com, robin.murphy@arm.com, "kirill.shutemov@linux.intel.com" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" T24gMi8yMy8yMDIyIDU6NDYgUE0sIFRpYW55dSBMYW4gd3JvdGU6Cj4gCj4gCj4gT24gMi8yMy8y MDIyIDEyOjAwIEFNLCBDaHJpc3RvcGggSGVsbHdpZyB3cm90ZToKPj4gT24gVHVlLCBGZWIgMjIs IDIwMjIgYXQgMTE6MDc6MTlQTSArMDgwMCwgVGlhbnl1IExhbiB3cm90ZToKPj4+IFRoYW5rcyBm b3IgeW91ciBjb21tZW50LiBUaGF0IG1lYW5zIHdlIG5lZWQgdG8gZXhwb3NlIGFuCj4+PiBzd2lv dGxiX2RldmljZV9pbml0KCkgaW50ZXJmYWNlIHRvIGFsbG9jYXRlIGJvdW5jZSBidWZmZXIgYW5k IGluaXRpYWxpemUKPj4+IGlvIHRsYiBtZW0gZW50cnkuIERNQSBBUEkgQ3VycmVudMKgIHJtZW1f c3dpb3RsYl9kZXZpY2VfaW5pdCgpIG9ubHkgd29ya3MKPj4+IGZvciBwbGF0Zm9ybSB3aXRoIGRl dmljZSB0cmVlLiBUaGUgbmV3IEFQSSBzaG91bGQgYmUgY2FsbGVkIGluIHRoZSBidXMKPj4+IGRy aXZlciBvciBuZXcgRE1BIEFQSS4gQ291bGQgeW91IGNoZWNrIHdoZXRoZXIgdGhpcyBpcyBhIHJp Z2h0IHdheSAKPj4+IGJlZm9yZQo+Pj4gd2Ugc3RhcnQgdGhlIHdvcmsuCj4+Cj4+IERvIHRoZXNl IFZNcyB1c2UgQUNQST/CoCBXZSdkIHByb2JhYmx5IHJlYWxseSB3YW50IHNvbWUga2luZCBvZiBo aWdoZXIKPj4gbGV2ZWwgY29uZmlndXJhdGlvbiBhbmQgbm90IGhhdmUgdGhlIGRyaXZlcnMgcmVx dWVzdCBpdCB0aGVtc2VsdmVzLgo+IAo+IFllcywgSHlwZXItViBpc29sYXRpb24gVk0gdXNlcyBB Q1BJLiBEZXZpY2VzIGFyZSBlbnVtZXJhdGVkIHZpYSB2bWJ1cyAKPiBob3N0IGFuZCB0aGVyZSBp cyBubyBjaGlsZCBkZXZpY2UgaW5mb3JtYXRpb24gaW4gQUNQSSB0YWJsZS4gVGhlIGhvc3QgCj4g ZHJpdmVyIHNlZW1zIHRvIGJlIHRoZSByaWdodCBwbGFjZSB0byBjYWxsIG5ldyBBUEkuCgpIaSBD aHJpc3RvcGg6CiAgICAgIE9uZSBtb3JlIHBlcnNwZWN0aXZlIGlzIHRoYXQgb25lIGRldmljZSBt YXkgaGF2ZSBtdWx0aXBsZSBxdWV1ZXMgCmFuZCBlYWNoIHF1ZXVlcyBzaG91bGQgaGF2ZSBpbmRl cGVuZGVudCBzd2lvdGxiIGJvdW5jZSBidWZmZXIgdG8gYXZvaWQgCnNwaW4gbG9jayBvdmVyaGVh ZC4gVGhlIG51bWJlciBvZiBxdWV1ZXMgaXMgb25seSBhdmFpbGFibGUgaW4gdGhlIGRldmljZQpk cml2ZXIuIFRoaXMgbWVhbnMgbmV3IEFQSSBuZWVkcyB0byBiZSBjYWxsZWQgaW4gdGhlIGRldmlj ZSBkcml2ZXIgCmFjY29yZGluZyB0byBxdWV1ZSBudW1iZXIuCl9fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fCmlvbW11IG1haWxpbmcgbGlzdAppb21tdUBsaXN0 cy5saW51eC1mb3VuZGF0aW9uLm9yZwpodHRwczovL2xpc3RzLmxpbnV4Zm91bmRhdGlvbi5vcmcv bWFpbG1hbi9saXN0aW5mby9pb21tdQ==