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bh=nma5RrDL02zgQCnQAmwMQggmlffp24gdJp2OtX7ZPuI=; b=GrhwezraI6jnv9CqC41BRlV+ikJ2kjxywJ0d1ottoP3WOPhMT58IiMWFsPgBvmjDCGXm2D 1L40DaJWJiw1M0qsNl7InN87vWMiDOiGb9MDWFRVzvZ5OirAT5MBy3wgv/UCQF6GrWAnX1 dlLKILG0b9a7CJGfEjmM91aLfuu9cIc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-295-1LGCv3TxNmmITacLXAFtsw-1; Fri, 12 Feb 2021 03:55:20 -0500 X-MC-Unique: 1LGCv3TxNmmITacLXAFtsw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 176EB6D4E0; Fri, 12 Feb 2021 08:55:18 +0000 (UTC) Received: from [10.36.114.34] (ovpn-114-34.ams2.redhat.com [10.36.114.34]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B842F62AF8; Fri, 12 Feb 2021 08:55:10 +0000 (UTC) Subject: Re: [PATCH v13 02/15] iommu: Introduce bind/unbind_guest_msi To: Keqian Zhu , eric.auger.pro@gmail.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, will@kernel.org, joro@8bytes.org, maz@kernel.org, robin.murphy@arm.com, alex.williamson@redhat.com References: <20201118112151.25412-1-eric.auger@redhat.com> <20201118112151.25412-3-eric.auger@redhat.com> <6a70d93d-329f-4129-bd90-03f8589c5de4@huawei.com> From: Auger Eric Message-ID: <1ef4f5ae-9ca6-7c6d-f8a9-31240e5688c2@redhat.com> Date: Fri, 12 Feb 2021 09:55:09 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <6a70d93d-329f-4129-bd90-03f8589c5de4@huawei.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Cc: jean-philippe@linaro.org, vivek.gautam@arm.com, zhangfei.gao@linaro.org 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hi Keqian, On 2/1/21 12:52 PM, Keqian Zhu wrote: > Hi Eric, > > On 2020/11/18 19:21, Eric Auger wrote: >> On ARM, MSI are translated by the SMMU. An IOVA is allocated >> for each MSI doorbell. If both the host and the guest are exposed >> with SMMUs, we end up with 2 different IOVAs allocated by each. >> guest allocates an IOVA (gIOVA) to map onto the guest MSI >> doorbell (gDB). The Host allocates another IOVA (hIOVA) to map >> onto the physical doorbell (hDB). >> >> So we end up with 2 untied mappings: >> S1 S2 >> gIOVA -> gDB >> hIOVA -> hDB >> >> Currently the PCI device is programmed by the host with hIOVA >> as MSI doorbell. So this does not work. >> >> This patch introduces an API to pass gIOVA/gDB to the host so >> that gIOVA can be reused by the host instead of re-allocating >> a new IOVA. So the goal is to create the following nested mapping: > Does the gDB can be reused under non-nested mode? Under non nested mode the hIOVA is allocated within the MSI reserved region exposed by the SMMU driver, [0x8000000, 80fffff]. see iommu_dma_prepare_msi/iommu_dma_get_msi_page in dma_iommu.c. this hIOVA is programmed in the physical device so that the physical SMMU translates it into the physical doorbell (hDB = host physical ITS doorbell). The gDB is not used at pIOMMU programming level. It is only used when setting up the KVM irq route. Hope this answers your question. > >> >> S1 S2 >> gIOVA -> gDB -> hDB >> >> and program the PCI device with gIOVA MSI doorbell. >> >> In case we have several devices attached to this nested domain >> (devices belonging to the same group), they cannot be isolated >> on guest side either. So they should also end up in the same domain >> on guest side. We will enforce that all the devices attached to >> the host iommu domain use the same physical doorbell and similarly >> a single virtual doorbell mapping gets registered (1 single >> virtual doorbell is used on guest as well). >> > [...] > >> + * >> + * The associated IOVA can be reused by the host to create a nested >> + * stage2 binding mapping translating into the physical doorbell used >> + * by the devices attached to the domain. >> + * >> + * All devices within the domain must share the same physical doorbell. >> + * A single MSI GIOVA/GPA mapping can be attached to an iommu_domain. >> + */ >> + >> +int iommu_bind_guest_msi(struct iommu_domain *domain, >> + dma_addr_t giova, phys_addr_t gpa, size_t size) >> +{ >> + if (unlikely(!domain->ops->bind_guest_msi)) >> + return -ENODEV; >> + >> + return domain->ops->bind_guest_msi(domain, giova, gpa, size); >> +} >> +EXPORT_SYMBOL_GPL(iommu_bind_guest_msi); >> + >> +void iommu_unbind_guest_msi(struct iommu_domain *domain, >> + dma_addr_t iova) > nit: s/iova/giova sure > >> +{ >> + if (unlikely(!domain->ops->unbind_guest_msi)) >> + return; >> + >> + domain->ops->unbind_guest_msi(domain, iova); >> +} >> +EXPORT_SYMBOL_GPL(iommu_unbind_guest_msi); >> + > [...] > > Thanks, > Keqian > Thanks Eric _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu