From patchwork Tue Mar 9 06:22:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shenming Lu X-Patchwork-Id: 12124223 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33D17C4332B for ; Tue, 9 Mar 2021 06:23:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 042ED652B1 for ; Tue, 9 Mar 2021 06:23:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230046AbhCIGW7 (ORCPT ); Tue, 9 Mar 2021 01:22:59 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:13584 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229911AbhCIGWa (ORCPT ); Tue, 9 Mar 2021 01:22:30 -0500 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4DvlSp0bKmz17Hgx; Tue, 9 Mar 2021 14:20:42 +0800 (CST) Received: from DESKTOP-7FEPK9S.china.huawei.com (10.174.184.135) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.498.0; Tue, 9 Mar 2021 14:22:19 +0800 From: Shenming Lu To: Alex Williamson , Cornelia Huck , Will Deacon , Robin Murphy , Joerg Roedel , Jean-Philippe Brucker , Eric Auger , , , , , CC: Kevin Tian , , Christoph Hellwig , Lu Baolu , Jonathan Cameron , Barry Song , , , , Subject: [RFC PATCH v2 3/6] vfio: Add a page fault handler Date: Tue, 9 Mar 2021 14:22:04 +0800 Message-ID: <20210309062207.505-4-lushenming@huawei.com> X-Mailer: git-send-email 2.27.0.windows.1 In-Reply-To: <20210309062207.505-1-lushenming@huawei.com> References: <20210309062207.505-1-lushenming@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.174.184.135] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org VFIO manages the DMA mapping itself. To support IOPF for VFIO devices, we add a VFIO page fault handler to serve the reported page faults from the IOMMU driver. Besides, we can pre-map more pages than requested at once to optimize for fewer page fault handlings. Signed-off-by: Shenming Lu --- drivers/vfio/vfio.c | 35 +++++++ drivers/vfio/vfio_iommu_type1.c | 167 ++++++++++++++++++++++++++++++++ include/linux/vfio.h | 5 + 3 files changed, 207 insertions(+) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 38779e6fd80c..77b29bbd3027 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -2354,6 +2354,41 @@ struct iommu_domain *vfio_group_iommu_domain(struct vfio_group *group) } EXPORT_SYMBOL_GPL(vfio_group_iommu_domain); +int vfio_iommu_dev_fault_handler(struct iommu_fault *fault, void *data) +{ + struct device *dev = (struct device *)data; + struct vfio_container *container; + struct vfio_group *group; + struct vfio_iommu_driver *driver; + int ret; + + if (!dev) + return -EINVAL; + + group = vfio_group_get_from_dev(dev); + if (!group) + return -ENODEV; + + ret = vfio_group_add_container_user(group); + if (ret) + goto out; + + container = group->container; + driver = container->iommu_driver; + if (likely(driver && driver->ops->dma_map_iopf)) + ret = driver->ops->dma_map_iopf(container->iommu_data, + fault, dev); + else + ret = -ENOTTY; + + vfio_group_try_dissolve_container(group); + +out: + vfio_group_put(group); + return ret; +} +EXPORT_SYMBOL_GPL(vfio_iommu_dev_fault_handler); + /** * Module/class support */ diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 03ccc11057af..167d52c1468b 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -3330,6 +3330,172 @@ static void vfio_iommu_type1_notify(void *iommu_data, wake_up_all(&iommu->vaddr_wait); } +/* + * To optimize for fewer page fault handlings, try to + * pre-map more pages than requested. + */ +#define IOPF_PREMAP_LEN 512 + +static void unpin_pages_iopf(struct vfio_dma *dma, + unsigned long pfn, unsigned long npages) +{ + while (npages--) + put_pfn(pfn++, dma->prot); +} + +/* + * Return 0 on success or a negative error code, the + * number of pages contiguously pinned is in @*pinned. + */ +static int pin_pages_iopf(struct vfio_dma *dma, unsigned long vaddr, + unsigned long npages, unsigned long *pfn_base, + unsigned long *pinned, struct vfio_batch *batch) +{ + struct mm_struct *mm; + unsigned long pfn; + int ret = 0; + *pinned = 0; + + mm = get_task_mm(dma->task); + if (!mm) + return -ENODEV; + + if (batch->size) { + *pfn_base = page_to_pfn(batch->pages[batch->offset]); + pfn = *pfn_base; + } else + *pfn_base = 0; + + while (npages) { + if (!batch->size) { + unsigned long req_pages = min_t(unsigned long, npages, + batch->capacity); + + ret = vaddr_get_pfns(mm, vaddr, req_pages, dma->prot, + &pfn, batch->pages); + if (ret < 0) + goto out; + + batch->size = ret; + batch->offset = 0; + ret = 0; + + if (!*pfn_base) + *pfn_base = pfn; + } + + while (true) { + if (pfn != *pfn_base + *pinned) + goto out; + + (*pinned)++; + npages--; + vaddr += PAGE_SIZE; + batch->offset++; + batch->size--; + + if (!batch->size) + break; + + pfn = page_to_pfn(batch->pages[batch->offset]); + } + + if (unlikely(disable_hugepages)) + break; + } + +out: + mmput(mm); + return ret; +} + +static int vfio_iommu_type1_dma_map_iopf(void *iommu_data, + struct iommu_fault *fault, + struct device *dev) +{ + struct vfio_iommu *iommu = iommu_data; + dma_addr_t iova = ALIGN_DOWN(fault->prm.addr, PAGE_SIZE); + struct vfio_dma *dma; + int access_flags = 0; + size_t premap_len, map_len, mapped_len = 0; + unsigned long bit_offset, npages, i, vaddr, pfn; + struct vfio_batch batch; + enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID; + struct iommu_page_response resp = {0}; + + mutex_lock(&iommu->lock); + + dma = vfio_find_dma(iommu, iova, PAGE_SIZE); + if (!dma) + goto out_invalid; + + if (fault->prm.perm & IOMMU_FAULT_PERM_READ) + access_flags |= IOMMU_READ; + if (fault->prm.perm & IOMMU_FAULT_PERM_WRITE) + access_flags |= IOMMU_WRITE; + if ((dma->prot & access_flags) != access_flags) + goto out_invalid; + + bit_offset = (iova - dma->iova) >> PAGE_SHIFT; + if (IOPF_MAPPED_BITMAP_GET(dma, bit_offset)) + goto out_success; + + premap_len = IOPF_PREMAP_LEN << PAGE_SHIFT; + npages = dma->size >> PAGE_SHIFT; + map_len = PAGE_SIZE; + for (i = bit_offset + 1; i < npages; i++) { + if (map_len >= premap_len || IOPF_MAPPED_BITMAP_GET(dma, i)) + break; + map_len += PAGE_SIZE; + } + vaddr = iova - dma->iova + dma->vaddr; + vfio_batch_init(&batch); + + while (map_len) { + int ret; + + ret = pin_pages_iopf(dma, vaddr + mapped_len, + map_len >> PAGE_SHIFT, &pfn, + &npages, &batch); + if (!npages) + break; + + if (vfio_iommu_map(iommu, iova + mapped_len, pfn, + npages, dma->prot)) { + unpin_pages_iopf(dma, pfn, npages); + vfio_batch_unpin(&batch, dma); + break; + } + + bitmap_set(dma->iopf_mapped_bitmap, + bit_offset + (mapped_len >> PAGE_SHIFT), npages); + + unpin_pages_iopf(dma, pfn, npages); + + map_len -= npages << PAGE_SHIFT; + mapped_len += npages << PAGE_SHIFT; + + if (ret) + break; + } + + vfio_batch_fini(&batch); + + if (!mapped_len) + goto out_invalid; + +out_success: + status = IOMMU_PAGE_RESP_SUCCESS; + +out_invalid: + mutex_unlock(&iommu->lock); + resp.version = IOMMU_PAGE_RESP_VERSION_1; + resp.grpid = fault->prm.grpid; + resp.code = status; + iommu_page_response(dev, &resp); + return 0; +} + static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = { .name = "vfio-iommu-type1", .owner = THIS_MODULE, @@ -3345,6 +3511,7 @@ static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = { .dma_rw = vfio_iommu_type1_dma_rw, .group_iommu_domain = vfio_iommu_type1_group_iommu_domain, .notify = vfio_iommu_type1_notify, + .dma_map_iopf = vfio_iommu_type1_dma_map_iopf, }; static int __init vfio_iommu_type1_init(void) diff --git a/include/linux/vfio.h b/include/linux/vfio.h index b7e18bde5aa8..73af317a4343 100644 --- a/include/linux/vfio.h +++ b/include/linux/vfio.h @@ -99,6 +99,9 @@ struct vfio_iommu_driver_ops { struct iommu_group *group); void (*notify)(void *iommu_data, enum vfio_iommu_notify_type event); + int (*dma_map_iopf)(void *iommu_data, + struct iommu_fault *fault, + struct device *dev); }; extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops); @@ -160,6 +163,8 @@ extern int vfio_unregister_notifier(struct device *dev, struct kvm; extern void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm); +extern int vfio_iommu_dev_fault_handler(struct iommu_fault *fault, void *data); + /* * Sub-module helpers */