Merge tag 'vfio-v4.8-rc1' of git://github.com/awilliam/linux-vfio

Pull VFIO updates from Alex Williamson:
 - Enable no-iommu mode for platform devices (Peng Fan)
 - Sub-page mmap for exclusive pages (Yongji Xie)
 - Use-after-free fix (Ilya Lesokhin)
 - Support for ACPI-based platform devices (Sinan Kaya)

* tag 'vfio-v4.8-rc1' of git://github.com/awilliam/linux-vfio:
  vfio: platform: check reset call return code during release
  vfio: platform: check reset call return code during open
  vfio, platform: make reset driver a requirement by default
  vfio: platform: call _RST method when using ACPI
  vfio: platform: add extra debug info argument to call reset
  vfio: platform: add support for ACPI probe
  vfio: platform: determine reset capability
  vfio: platform: move reset call to a common function
  vfio: platform: rename reset function
  vfio: fix possible use after free of vfio group
  vfio-pci: Allow to mmap sub-page MMIO BARs if the mmio page is exclusive
  vfio: platform: support No-IOMMU mode

drivers/vfio/pci/vfio_pci.c

@@ -110,6 +110,74 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev)
 	return (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA;
 }
 
+static void vfio_pci_probe_mmaps(struct vfio_pci_device *vdev)
+{
+	struct resource *res;
+	int bar;
+	struct vfio_pci_dummy_resource *dummy_res;
+
+	INIT_LIST_HEAD(&vdev->dummy_resources_list);
+
+	for (bar = PCI_STD_RESOURCES; bar <= PCI_STD_RESOURCE_END; bar++) {
+		res = vdev->pdev->resource + bar;
+
+		if (!IS_ENABLED(CONFIG_VFIO_PCI_MMAP))
+			goto no_mmap;
+
+		if (!(res->flags & IORESOURCE_MEM))
+			goto no_mmap;
+
+		/*
+		 * The PCI core shouldn't set up a resource with a
+		 * type but zero size. But there may be bugs that
+		 * cause us to do that.
+		 */
+		if (!resource_size(res))
+			goto no_mmap;
+
+		if (resource_size(res) >= PAGE_SIZE) {
+			vdev->bar_mmap_supported[bar] = true;
+			continue;
+		}
+
+		if (!(res->start & ~PAGE_MASK)) {
+			/*
+			 * Add a dummy resource to reserve the remainder
+			 * of the exclusive page in case that hot-add
+			 * device's bar is assigned into it.
+			 */
+			dummy_res = kzalloc(sizeof(*dummy_res), GFP_KERNEL);
+			if (dummy_res == NULL)
+				goto no_mmap;
+
+			dummy_res->resource.name = "vfio sub-page reserved";
+			dummy_res->resource.start = res->end + 1;
+			dummy_res->resource.end = res->start + PAGE_SIZE - 1;
+			dummy_res->resource.flags = res->flags;
+			if (request_resource(res->parent,
+						&dummy_res->resource)) {
+				kfree(dummy_res);
+				goto no_mmap;
+			}
+			dummy_res->index = bar;
+			list_add(&dummy_res->res_next,
+					&vdev->dummy_resources_list);
+			vdev->bar_mmap_supported[bar] = true;
+			continue;
+		}
+		/*
+		 * Here we don't handle the case when the BAR is not page
+		 * aligned because we can't expect the BAR will be
+		 * assigned into the same location in a page in guest
+		 * when we passthrough the BAR. And it's hard to access
+		 * this BAR in userspace because we have no way to get
+		 * the BAR's location in a page.
+		 */
+no_mmap:
+		vdev->bar_mmap_supported[bar] = false;
+	}
+}
+
 static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev);
 static void vfio_pci_disable(struct vfio_pci_device *vdev);
 
@@ -218,12 +286,15 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
 		}
 	}
 
+	vfio_pci_probe_mmaps(vdev);
+
 	return 0;
 }
 
 static void vfio_pci_disable(struct vfio_pci_device *vdev)
 {
 	struct pci_dev *pdev = vdev->pdev;
+	struct vfio_pci_dummy_resource *dummy_res, *tmp;
 	int i, bar;
 
 	/* Stop the device from further DMA */
@@ -252,6 +323,13 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
 		vdev->barmap[bar] = NULL;
 	}
 
+	list_for_each_entry_safe(dummy_res, tmp,
+				 &vdev->dummy_resources_list, res_next) {
+		list_del(&dummy_res->res_next);
+		release_resource(&dummy_res->resource);
+		kfree(dummy_res);
+	}
+
 	vdev->needs_reset = true;
 
 	/*
@@ -623,9 +701,7 @@ 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);
@@ -1049,16 +1125,16 @@ 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) {

drivers/vfio/pci/vfio_pci_private.h

@@ -57,9 +57,16 @@ struct vfio_pci_region {
 	u32				flags;
 };
 
+struct vfio_pci_dummy_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;
@@ -88,6 +95,7 @@ struct vfio_pci_device {
 	int			refcnt;
 	struct eventfd_ctx	*err_trigger;
 	struct eventfd_ctx	*req_trigger;
+	struct list_head	dummy_resources_list;
 };
 
 #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX)

drivers/vfio/platform/vfio_amba.c

@@ -68,6 +68,7 @@ static int vfio_amba_probe(struct amba_device *adev, const struct amba_id *id)
 	vdev->get_resource = get_amba_resource;
 	vdev->get_irq = get_amba_irq;
 	vdev->parent_module = THIS_MODULE;
+	vdev->reset_required = false;
 
 	ret = vfio_platform_probe_common(vdev, &adev->dev);
 	if (ret) {

drivers/vfio/platform/vfio_platform.c

@@ -23,6 +23,10 @@
 #define DRIVER_AUTHOR   "Antonios Motakis <a.motakis@virtualopensystems.com>"
 #define DRIVER_DESC     "VFIO for platform devices - User Level meta-driver"
 
+static bool reset_required = true;
+module_param(reset_required, bool, 0444);
+MODULE_PARM_DESC(reset_required, "override reset requirement (default: 1)");
+
 /* probing devices from the linux platform bus */
 
 static struct resource *get_platform_resource(struct vfio_platform_device *vdev,
@@ -66,6 +70,7 @@ static int vfio_platform_probe(struct platform_device *pdev)
 	vdev->get_resource = get_platform_resource;
 	vdev->get_irq = get_platform_irq;
 	vdev->parent_module = THIS_MODULE;
+	vdev->reset_required = reset_required;
 
 	ret = vfio_platform_probe_common(vdev, &pdev->dev);
 	if (ret)

drivers/vfio/platform/vfio_platform_common.c

@@ -13,6 +13,7 @@
  */
 
 #include <linux/device.h>
+#include <linux/acpi.h>
 #include <linux/iommu.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
@@ -27,6 +28,8 @@
 #define DRIVER_AUTHOR   "Antonios Motakis <a.motakis@virtualopensystems.com>"
 #define DRIVER_DESC     "VFIO platform base module"
 
+#define VFIO_PLATFORM_IS_ACPI(vdev) ((vdev)->acpihid != NULL)
+
 static LIST_HEAD(reset_list);
 static DEFINE_MUTEX(driver_lock);
 
@@ -41,7 +44,7 @@ static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
 		if (!strcmp(iter->compat, compat) &&
 			try_module_get(iter->owner)) {
 			*module = iter->owner;
-			reset_fn = iter->reset;
+			reset_fn = iter->of_reset;
 			break;
 		}
 	}
@@ -49,20 +52,91 @@ static vfio_platform_reset_fn_t vfio_platform_lookup_reset(const char *compat,
 	return reset_fn;
 }
 
-static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
+static int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
+				    struct device *dev)
+{
+	struct acpi_device *adev;
+
+	if (acpi_disabled)
+		return -ENOENT;
+
+	adev = ACPI_COMPANION(dev);
+	if (!adev) {
+		pr_err("VFIO: ACPI companion device not found for %s\n",
+			vdev->name);
+		return -ENODEV;
+	}
+
+#ifdef CONFIG_ACPI
+	vdev->acpihid = acpi_device_hid(adev);
+#endif
+	return WARN_ON(!vdev->acpihid) ? -EINVAL : 0;
+}
+
+int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev,
+				  const char **extra_dbg)
 {
-	vdev->reset = vfio_platform_lookup_reset(vdev->compat,
+#ifdef CONFIG_ACPI
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct device *dev = vdev->device;
+	acpi_handle handle = ACPI_HANDLE(dev);
+	acpi_status acpi_ret;
+
+	acpi_ret = acpi_evaluate_object(handle, "_RST", NULL, &buffer);
+	if (ACPI_FAILURE(acpi_ret)) {
+		if (extra_dbg)
+			*extra_dbg = acpi_format_exception(acpi_ret);
+		return -EINVAL;
+	}
+
+	return 0;
+#else
+	return -ENOENT;
+#endif
+}
+
+bool vfio_platform_acpi_has_reset(struct vfio_platform_device *vdev)
+{
+#ifdef CONFIG_ACPI
+	struct device *dev = vdev->device;
+	acpi_handle handle = ACPI_HANDLE(dev);
+
+	return acpi_has_method(handle, "_RST");
+#else
+	return false;
+#endif
+}
+
+static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
+{
+	if (VFIO_PLATFORM_IS_ACPI(vdev))
+		return vfio_platform_acpi_has_reset(vdev);
+
+	return vdev->of_reset ? true : false;
+}
+
+static int vfio_platform_get_reset(struct vfio_platform_device *vdev)
+{
+	if (VFIO_PLATFORM_IS_ACPI(vdev))
+		return vfio_platform_acpi_has_reset(vdev) ? 0 : -ENOENT;
+
+	vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
 						    &vdev->reset_module);
-	if (!vdev->reset) {
+	if (!vdev->of_reset) {
 		request_module("vfio-reset:%s", vdev->compat);
-		vdev->reset = vfio_platform_lookup_reset(vdev->compat,
+		vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
 							&vdev->reset_module);
 	}
+
+	return vdev->of_reset ? 0 : -ENOENT;
 }
 
 static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
 {
-	if (vdev->reset)
+	if (VFIO_PLATFORM_IS_ACPI(vdev))
+		return;
+
+	if (vdev->of_reset)
 		module_put(vdev->reset_module);
 }
 
@@ -134,6 +208,21 @@ static void vfio_platform_regions_cleanup(struct vfio_platform_device *vdev)
 	kfree(vdev->regions);
 }
 
+static int vfio_platform_call_reset(struct vfio_platform_device *vdev,
+				    const char **extra_dbg)
+{
+	if (VFIO_PLATFORM_IS_ACPI(vdev)) {
+		dev_info(vdev->device, "reset\n");
+		return vfio_platform_acpi_call_reset(vdev, extra_dbg);
+	} else if (vdev->of_reset) {
+		dev_info(vdev->device, "reset\n");
+		return vdev->of_reset(vdev);
+	}
+
+	dev_warn(vdev->device, "no reset function found!\n");
+	return -EINVAL;
+}
+
 static void vfio_platform_release(void *device_data)
 {
 	struct vfio_platform_device *vdev = device_data;
@@ -141,11 +230,14 @@ static void vfio_platform_release(void *device_data)
 	mutex_lock(&driver_lock);
 
 	if (!(--vdev->refcnt)) {
-		if (vdev->reset) {
-			dev_info(vdev->device, "reset\n");
-			vdev->reset(vdev);
-		} else {
-			dev_warn(vdev->device, "no reset function found!\n");
+		const char *extra_dbg = NULL;
+		int ret;
+
+		ret = vfio_platform_call_reset(vdev, &extra_dbg);
+		if (ret && vdev->reset_required) {
+			dev_warn(vdev->device, "reset driver is required and reset call failed in release (%d) %s\n",
+				 ret, extra_dbg ? extra_dbg : "");
+			WARN_ON(1);
 		}
 		vfio_platform_regions_cleanup(vdev);
 		vfio_platform_irq_cleanup(vdev);
@@ -167,6 +259,8 @@ static int vfio_platform_open(void *device_data)
 	mutex_lock(&driver_lock);
 
 	if (!vdev->refcnt) {
+		const char *extra_dbg = NULL;
+
 		ret = vfio_platform_regions_init(vdev);
 		if (ret)
 			goto err_reg;
@@ -175,11 +269,11 @@ static int vfio_platform_open(void *device_data)
 		if (ret)
 			goto err_irq;
 
-		if (vdev->reset) {
-			dev_info(vdev->device, "reset\n");
-			vdev->reset(vdev);
-		} else {
-			dev_warn(vdev->device, "no reset function found!\n");
+		ret = vfio_platform_call_reset(vdev, &extra_dbg);
+		if (ret && vdev->reset_required) {
+			dev_warn(vdev->device, "reset driver is required and reset call failed in open (%d) %s\n",
+				 ret, extra_dbg ? extra_dbg : "");
+			goto err_rst;
 		}
 	}
 
@@ -188,6 +282,8 @@ static int vfio_platform_open(void *device_data)
 	mutex_unlock(&driver_lock);
 	return 0;
 
+err_rst:
+	vfio_platform_irq_cleanup(vdev);
 err_irq:
 	vfio_platform_regions_cleanup(vdev);
 err_reg:
@@ -213,7 +309,7 @@ static long vfio_platform_ioctl(void *device_data,
 		if (info.argsz < minsz)
 			return -EINVAL;
 
-		if (vdev->reset)
+		if (vfio_platform_has_reset(vdev))
 			vdev->flags |= VFIO_DEVICE_FLAGS_RESET;
 		info.flags = vdev->flags;
 		info.num_regions = vdev->num_regions;
@@ -312,10 +408,7 @@ static long vfio_platform_ioctl(void *device_data,
 		return ret;
 
 	} else if (cmd == VFIO_DEVICE_RESET) {
-		if (vdev->reset)
-			return vdev->reset(vdev);
-		else
-			return -EINVAL;
+		return vfio_platform_call_reset(vdev, NULL);
 	}
 
 	return -ENOTTY;
@@ -544,6 +637,37 @@ static const struct vfio_device_ops vfio_platform_ops = {
 	.mmap		= vfio_platform_mmap,
 };
 
+int vfio_platform_of_probe(struct vfio_platform_device *vdev,
+			   struct device *dev)
+{
+	int ret;
+
+	ret = device_property_read_string(dev, "compatible",
+					  &vdev->compat);
+	if (ret)
+		pr_err("VFIO: cannot retrieve compat for %s\n",
+			vdev->name);
+
+	return ret;
+}
+
+/*
+ * There can be two kernel build combinations. One build where
+ * ACPI is not selected in Kconfig and another one with the ACPI Kconfig.
+ *
+ * In the first case, vfio_platform_acpi_probe will return since
+ * acpi_disabled is 1. DT user will not see any kind of messages from
+ * ACPI.
+ *
+ * In the second case, both DT and ACPI is compiled in but the system is
+ * booting with any of these combinations.
+ *
+ * If the firmware is DT type, then acpi_disabled is 1. The ACPI probe routine
+ * terminates immediately without any messages.
+ *
+ * If the firmware is ACPI type, then acpi_disabled is 0. All other checks are
+ * valid checks. We cannot claim that this system is DT.
+ */
 int vfio_platform_probe_common(struct vfio_platform_device *vdev,
 			       struct device *dev)
 {
@@ -553,15 +677,23 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
 	if (!vdev)
 		return -EINVAL;
 
-	ret = device_property_read_string(dev, "compatible", &vdev->compat);
-	if (ret) {
-		pr_err("VFIO: cannot retrieve compat for %s\n", vdev->name);
-		return -EINVAL;
-	}
+	ret = vfio_platform_acpi_probe(vdev, dev);
+	if (ret)
+		ret = vfio_platform_of_probe(vdev, dev);
+
+	if (ret)
+		return ret;
 
 	vdev->device = dev;
 
-	group = iommu_group_get(dev);
+	ret = vfio_platform_get_reset(vdev);
+	if (ret && vdev->reset_required) {
+		pr_err("vfio: no reset function found for device %s\n",
+		       vdev->name);
+		return ret;
+	}
+
+	group = vfio_iommu_group_get(dev);
 	if (!group) {
 		pr_err("VFIO: No IOMMU group for device %s\n", vdev->name);
 		return -EINVAL;
@@ -569,12 +701,10 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
 
 	ret = vfio_add_group_dev(dev, &vfio_platform_ops, vdev);
 	if (ret) {
-		iommu_group_put(group);
+		vfio_iommu_group_put(group, dev);
 		return ret;
 	}
 
-	vfio_platform_get_reset(vdev);
-
 	mutex_init(&vdev->igate);
 
 	return 0;
@@ -589,7 +719,7 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev)
 
 	if (vdev) {
 		vfio_platform_put_reset(vdev);
-		iommu_group_put(dev->iommu_group);
+		vfio_iommu_group_put(dev->iommu_group, dev);
 	}
 
 	return vdev;
@@ -611,7 +741,7 @@ void vfio_platform_unregister_reset(const char *compat,
 
 	mutex_lock(&driver_lock);
 	list_for_each_entry_safe(iter, temp, &reset_list, link) {
-		if (!strcmp(iter->compat, compat) && (iter->reset == fn)) {
+		if (!strcmp(iter->compat, compat) && (iter->of_reset == fn)) {
 			list_del(&iter->link);
 			break;
 		}

drivers/vfio/platform/vfio_platform_private.h

@@ -58,6 +58,7 @@ struct vfio_platform_device {
 	struct mutex			igate;
 	struct module			*parent_module;
 	const char			*compat;
+	const char			*acpihid;
 	struct module			*reset_module;
 	struct device			*device;
 
@@ -71,7 +72,9 @@ struct vfio_platform_device {
 	struct resource*
 		(*get_resource)(struct vfio_platform_device *vdev, int i);
 	int	(*get_irq)(struct vfio_platform_device *vdev, int i);
-	int	(*reset)(struct vfio_platform_device *vdev);
+	int	(*of_reset)(struct vfio_platform_device *vdev);
+
+	bool				reset_required;
 };
 
 typedef int (*vfio_platform_reset_fn_t)(struct vfio_platform_device *vdev);
@@ -80,7 +83,7 @@ struct vfio_platform_reset_node {
 	struct list_head link;
 	char *compat;
 	struct module *owner;
-	vfio_platform_reset_fn_t reset;
+	vfio_platform_reset_fn_t of_reset;
 };
 
 extern int vfio_platform_probe_common(struct vfio_platform_device *vdev,
@@ -103,7 +106,7 @@ extern void vfio_platform_unregister_reset(const char *compat,
 static struct vfio_platform_reset_node __reset ## _node = {	\
 	.owner = THIS_MODULE,					\
 	.compat = __compat,					\
-	.reset = __reset,					\
+	.of_reset = __reset,					\
 };								\
 __vfio_platform_register_reset(&__reset ## _node)
 

drivers/vfio/vfio.c

@@ -1711,8 +1711,8 @@ EXPORT_SYMBOL_GPL(vfio_group_get_external_user);
 
 void vfio_group_put_external_user(struct vfio_group *group)
 {
-	vfio_group_put(group);
 	vfio_group_try_dissolve_container(group);
+	vfio_group_put(group);
 }
 EXPORT_SYMBOL_GPL(vfio_group_put_external_user);