From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp01.au.ibm.com (e23smtp01.au.ibm.com [202.81.31.143]) (using TLSv1.2 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3qfVXC1H9BzDqQH for ; Tue, 5 Apr 2016 23:47:07 +1000 (AEST) Received: from localhost by e23smtp01.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 5 Apr 2016 23:47:06 +1000 Received: from d23relay08.au.ibm.com (d23relay08.au.ibm.com [9.185.71.33]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 8BFB72BB0057 for ; Tue, 5 Apr 2016 23:46:49 +1000 (EST) Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay08.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u35DkfCQ42008624 for ; Tue, 5 Apr 2016 23:46:49 +1000 Received: from d23av03.au.ibm.com (localhost [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u35DkGXP031261 for ; Tue, 5 Apr 2016 23:46:17 +1000 From: Yongji Xie To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org Cc: bhelgaas@google.com, corbet@lwn.net, aik@ozlabs.ru, alex.williamson@redhat.com, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, warrier@linux.vnet.ibm.com, zhong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com, gwshan@linux.vnet.ibm.com, Yongji Xie Subject: [RFC v5 5/7] vfio-pci: Allow to mmap sub-page MMIO BARs if the mmio page is exclusive Date: Tue, 5 Apr 2016 21:43:33 +0800 Message-Id: <1459863813-2830-6-git-send-email-xyjxie@linux.vnet.ibm.com> In-Reply-To: <1459863813-2830-1-git-send-email-xyjxie@linux.vnet.ibm.com> References: <1459863813-2830-1-git-send-email-xyjxie@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Current vfio-pci implementation disallows to mmap sub-page(size < PAGE_SIZE) MMIO BARs because these BARs' mmio page may be shared with other BARs. But we should allow to mmap these sub-page MMIO BARs if we can make sure these BARs' mmio page will not be shared with other BARs. To acheive that, we firstly need to enforce all PCI MMIO BARs to be page aligned like the commit "PCI: Add support for enforcing all MMIO BARs to be page aligned" does. Most of PCI BARs will be assigned into an exclusive page with a hole. Then, we must make sure that hot-add device's BAR will never be assigned into the hole. So we add shadow resources and put them into the hole in this patch. With these two guarantees, I think it should be safe to mmap sub-page BAR. Signed-off-by: Yongji Xie --- drivers/vfio/pci/vfio_pci.c | 58 ++++++++++++++++++++++++++++++----- drivers/vfio/pci/vfio_pci_private.h | 8 +++++ 2 files changed, 59 insertions(+), 7 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 98059df..c60d790 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -110,13 +110,47 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev) return (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA; } +static bool vfio_pci_bar_mmap_supported(struct vfio_pci_device *vdev, int index) +{ + struct resource *res = vdev->pdev->resource + index; + struct vfio_pci_shadow_resource *shadow_res; + + if (IS_ENABLED(CONFIG_VFIO_PCI_MMAP) && res->flags & IORESOURCE_MEM && + resource_size(res) > 0) { + if (resource_size(res) >= PAGE_SIZE) + return true; + + if (!(res->start & ~PAGE_MASK)) { + /* + * Add shadow resource for sub-page bar whose mmio + * page is exclusive in case that hot-add device's + * bar is assigned into the mem hole. + */ + shadow_res = kzalloc(sizeof(*shadow_res), GFP_KERNEL); + shadow_res->resource.start = res->end + 1; + shadow_res->resource.end = res->start + PAGE_SIZE; + shadow_res->resource.flags = res->flags; + if (request_resource(res->parent, + &shadow_res->resource)) { + kfree(shadow_res); + return false; + } + shadow_res->index = index; + list_add(&shadow_res->res_next, + &vdev->shadow_resources_list); + return true; + } + } + return false; +} + static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev); static void vfio_pci_disable(struct vfio_pci_device *vdev); static int vfio_pci_enable(struct vfio_pci_device *vdev) { struct pci_dev *pdev = vdev->pdev; - int ret; + int ret, bar; u16 cmd; u8 msix_pos; @@ -183,12 +217,17 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev) } } + for (bar = PCI_STD_RESOURCES; bar <= PCI_STD_RESOURCE_END; bar++) { + vdev->bar_mmap_supported[bar] = + vfio_pci_bar_mmap_supported(vdev, bar); + } return 0; } static void vfio_pci_disable(struct vfio_pci_device *vdev) { struct pci_dev *pdev = vdev->pdev; + struct vfio_pci_shadow_resource *shadow_res; int i, bar; /* Stop the device from further DMA */ @@ -217,6 +256,13 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev) vdev->barmap[bar] = NULL; } + list_for_each_entry(shadow_res, &vdev->shadow_resources_list, + res_next) { + list_del(&shadow_res->res_next); + release_resource(&shadow_res->resource); + kfree(shadow_res); + } + vdev->needs_reset = true; /* @@ -587,9 +633,7 @@ static long vfio_pci_ioctl(void *device_data, info.flags = VFIO_REGION_INFO_FLAG_READ | VFIO_REGION_INFO_FLAG_WRITE; - if (IS_ENABLED(CONFIG_VFIO_PCI_MMAP) && - pci_resource_flags(pdev, info.index) & - IORESOURCE_MEM && info.size >= PAGE_SIZE) { + if (vdev->bar_mmap_supported[info.index]) { info.flags |= VFIO_REGION_INFO_FLAG_MMAP; if (info.index == vdev->msix_bar) { ret = msix_sparse_mmap_cap(vdev, &caps); @@ -1011,16 +1055,16 @@ static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma) return -EINVAL; if (index >= VFIO_PCI_ROM_REGION_INDEX) return -EINVAL; - if (!(pci_resource_flags(pdev, index) & IORESOURCE_MEM)) + if (!vdev->bar_mmap_supported[index]) return -EINVAL; - phys_len = pci_resource_len(pdev, index); + phys_len = PAGE_ALIGN(pci_resource_len(pdev, index)); req_len = vma->vm_end - vma->vm_start; pgoff = vma->vm_pgoff & ((1U << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1); req_start = pgoff << PAGE_SHIFT; - if (phys_len < PAGE_SIZE || req_start + req_len > phys_len) + if (req_start + req_len > phys_len) return -EINVAL; if (index == vdev->msix_bar) { diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h index 8a7d546..0ea4c62 100644 --- a/drivers/vfio/pci/vfio_pci_private.h +++ b/drivers/vfio/pci/vfio_pci_private.h @@ -57,9 +57,16 @@ struct vfio_pci_region { u32 flags; }; +struct vfio_pci_shadow_resource { + struct resource resource; + int index; + struct list_head res_next; +}; + struct vfio_pci_device { struct pci_dev *pdev; void __iomem *barmap[PCI_STD_RESOURCE_END + 1]; + bool bar_mmap_supported[PCI_STD_RESOURCE_END + 1]; u8 *pci_config_map; u8 *vconfig; struct perm_bits *msi_perm; @@ -87,6 +94,7 @@ struct vfio_pci_device { int refcnt; struct eventfd_ctx *err_trigger; struct eventfd_ctx *req_trigger; + struct list_head shadow_resources_list; }; #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX) -- 1.7.9.5