From patchwork Mon Sep 7 10:17:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ajay Kaher X-Patchwork-Id: 310110 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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 A0068C433E2 for ; Mon, 7 Sep 2020 10:21:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A413205CB for ; Mon, 7 Sep 2020 10:21:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728949AbgIGKVp (ORCPT ); Mon, 7 Sep 2020 06:21:45 -0400 Received: from ex13-edg-ou-002.vmware.com ([208.91.0.190]:56107 "EHLO EX13-EDG-OU-002.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728829AbgIGKVn (ORCPT ); Mon, 7 Sep 2020 06:21:43 -0400 Received: from sc9-mailhost3.vmware.com (10.113.161.73) by EX13-EDG-OU-002.vmware.com (10.113.208.156) with Microsoft SMTP Server id 15.0.1156.6; Mon, 7 Sep 2020 03:21:24 -0700 Received: from akaher-virtual-machine.eng.vmware.com (unknown [10.197.103.239]) by sc9-mailhost3.vmware.com (Postfix) with ESMTP id E93DC40271; Mon, 7 Sep 2020 03:21:24 -0700 (PDT) From: Ajay Kaher To: CC: , , , , , , , , , Subject: [PATCH v4.19.y 2/3] vfio-pci: Fault mmaps to enable vma tracking Date: Mon, 7 Sep 2020 15:47:21 +0530 Message-ID: <1599473843-34234-2-git-send-email-akaher@vmware.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1599473843-34234-1-git-send-email-akaher@vmware.com> References: <1599473843-34234-1-git-send-email-akaher@vmware.com> MIME-Version: 1.0 Received-SPF: None (EX13-EDG-OU-002.vmware.com: akaher@vmware.com does not designate permitted sender hosts) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Alex Williamson commit 11c4cd07ba111a09f49625f9e4c851d83daf0a22 upstream. Rather than calling remap_pfn_range() when a region is mmap'd, setup a vm_ops handler to support dynamic faulting of the range on access. This allows us to manage a list of vmas actively mapping the area that we can later use to invalidate those mappings. The open callback invalidates the vma range so that all tracking is inserted in the fault handler and removed in the close handler. Reviewed-by: Peter Xu Signed-off-by: Alex Williamson [Ajay: Regenerated the patch for v4.19] Signed-off-by: Ajay Kaher --- drivers/vfio/pci/vfio_pci.c | 76 ++++++++++++++++++++++++++++++++++++- drivers/vfio/pci/vfio_pci_private.h | 7 ++++ 2 files changed, 81 insertions(+), 2 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 66783a3..3cd5960 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -1121,6 +1121,70 @@ static ssize_t vfio_pci_write(void *device_data, const char __user *buf, return vfio_pci_rw(device_data, (char __user *)buf, count, ppos, true); } +static int vfio_pci_add_vma(struct vfio_pci_device *vdev, + struct vm_area_struct *vma) +{ + struct vfio_pci_mmap_vma *mmap_vma; + + mmap_vma = kmalloc(sizeof(*mmap_vma), GFP_KERNEL); + if (!mmap_vma) + return -ENOMEM; + + mmap_vma->vma = vma; + + mutex_lock(&vdev->vma_lock); + list_add(&mmap_vma->vma_next, &vdev->vma_list); + mutex_unlock(&vdev->vma_lock); + + return 0; +} + +/* + * Zap mmaps on open so that we can fault them in on access and therefore + * our vma_list only tracks mappings accessed since last zap. + */ +static void vfio_pci_mmap_open(struct vm_area_struct *vma) +{ + zap_vma_ptes(vma, vma->vm_start, vma->vm_end - vma->vm_start); +} + +static void vfio_pci_mmap_close(struct vm_area_struct *vma) +{ + struct vfio_pci_device *vdev = vma->vm_private_data; + struct vfio_pci_mmap_vma *mmap_vma; + + mutex_lock(&vdev->vma_lock); + list_for_each_entry(mmap_vma, &vdev->vma_list, vma_next) { + if (mmap_vma->vma == vma) { + list_del(&mmap_vma->vma_next); + kfree(mmap_vma); + break; + } + } + mutex_unlock(&vdev->vma_lock); +} + +static vm_fault_t vfio_pci_mmap_fault(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + struct vfio_pci_device *vdev = vma->vm_private_data; + + if (vfio_pci_add_vma(vdev, vma)) + return VM_FAULT_OOM; + + if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, + vma->vm_end - vma->vm_start, vma->vm_page_prot)) + return VM_FAULT_SIGBUS; + + return VM_FAULT_NOPAGE; +} + +static const struct vm_operations_struct vfio_pci_mmap_ops = { + .open = vfio_pci_mmap_open, + .close = vfio_pci_mmap_close, + .fault = vfio_pci_mmap_fault, +}; + static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma) { struct vfio_pci_device *vdev = device_data; @@ -1170,8 +1234,14 @@ static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma) vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); vma->vm_pgoff = (pci_resource_start(pdev, index) >> PAGE_SHIFT) + pgoff; - return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, - req_len, vma->vm_page_prot); + /* + * See remap_pfn_range(), called from vfio_pci_fault() but we can't + * change vm_flags within the fault handler. Set them now. + */ + vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; + vma->vm_ops = &vfio_pci_mmap_ops; + + return 0; } static void vfio_pci_request(void *device_data, unsigned int count) @@ -1243,6 +1313,8 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) spin_lock_init(&vdev->irqlock); mutex_init(&vdev->ioeventfds_lock); INIT_LIST_HEAD(&vdev->ioeventfds_list); + mutex_init(&vdev->vma_lock); + INIT_LIST_HEAD(&vdev->vma_list); ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev); if (ret) { diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h index cde3b5d..9743c93 100644 --- a/drivers/vfio/pci/vfio_pci_private.h +++ b/drivers/vfio/pci/vfio_pci_private.h @@ -76,6 +76,11 @@ struct vfio_pci_dummy_resource { struct list_head res_next; }; +struct vfio_pci_mmap_vma { + struct vm_area_struct *vma; + struct list_head vma_next; +}; + struct vfio_pci_device { struct pci_dev *pdev; void __iomem *barmap[PCI_STD_RESOURCE_END + 1]; @@ -111,6 +116,8 @@ struct vfio_pci_device { struct list_head dummy_resources_list; struct mutex ioeventfds_lock; struct list_head ioeventfds_list; + struct mutex vma_lock; + struct list_head vma_list; }; #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX)