Merge tag 'for-linus-5.6-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen updates from Juergen Gross:

 - fix a bug introduced in 5.5 in the Xen gntdev driver

 - fix the Xen balloon driver when running on ancient Xen versions

 - allow Xen stubdoms to control interrupt enable flags of
   passed-through PCI cards

 - release resources in Xen backends under memory pressure

* tag 'for-linus-5.6-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/blkback: Consistently insert one empty line between functions
  xen/blkback: Remove unnecessary static variable name prefixes
  xen/blkback: Squeeze page pools if a memory pressure is detected
  xenbus/backend: Protect xenbus callback with lock
  xenbus/backend: Add memory pressure handler callback
  xen/gntdev: Do not use mm notifiers with autotranslating guests
  xen/balloon: Support xend-based toolstack take two
  xen-pciback: optionally allow interrupt enable flag writes

drivers/xen/gntdev.c

@@ -1006,19 +1006,19 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 	}
 	mutex_unlock(&priv->lock);
 
-	/*
-	 * gntdev takes the address of the PTE in find_grant_ptes() and passes
-	 * it to the hypervisor in gntdev_map_grant_pages(). The purpose of
-	 * the notifier is to prevent the hypervisor pointer to the PTE from
-	 * going stale.
-	 *
-	 * Since this vma's mappings can't be touched without the mmap_sem,
-	 * and we are holding it now, there is no need for the notifier_range
-	 * locking pattern.
-	 */
-	mmu_interval_read_begin(&map->notifier);
-
 	if (use_ptemod) {
+		/*
+		 * gntdev takes the address of the PTE in find_grant_ptes() and
+		 * passes it to the hypervisor in gntdev_map_grant_pages(). The
+		 * purpose of the notifier is to prevent the hypervisor pointer
+		 * to the PTE from going stale.
+		 *
+		 * Since this vma's mappings can't be touched without the
+		 * mmap_sem, and we are holding it now, there is no need for
+		 * the notifier_range locking pattern.
+		 */
+		mmu_interval_read_begin(&map->notifier);
+
 		map->pages_vm_start = vma->vm_start;
 		err = apply_to_page_range(vma->vm_mm, vma->vm_start,
 					  vma->vm_end - vma->vm_start,

drivers/xen/xen-balloon.c

@@ -94,7 +94,7 @@ static void watch_target(struct xenbus_watch *watch,
 				  "%llu", &static_max) == 1))
 			static_max >>= PAGE_SHIFT - 10;
 		else
-			static_max = new_target;
+			static_max = balloon_stats.current_pages;
 
 		target_diff = (xen_pv_domain() || xen_initial_domain()) ? 0
 				: static_max - balloon_stats.target_pages;

drivers/xen/xen-pciback/conf_space.c

@@ -286,6 +286,43 @@ int xen_pcibk_config_write(struct pci_dev *dev, int offset, int size, u32 value)
 	return xen_pcibios_err_to_errno(err);
 }
 
+int xen_pcibk_get_interrupt_type(struct pci_dev *dev)
+{
+	int err;
+	u16 val;
+	int ret = 0;
+
+	err = pci_read_config_word(dev, PCI_COMMAND, &val);
+	if (err)
+		return err;
+	if (!(val & PCI_COMMAND_INTX_DISABLE))
+		ret |= INTERRUPT_TYPE_INTX;
+
+	/*
+	 * Do not trust dev->msi(x)_enabled here, as enabling could be done
+	 * bypassing the pci_*msi* functions, by the qemu.
+	 */
+	if (dev->msi_cap) {
+		err = pci_read_config_word(dev,
+				dev->msi_cap + PCI_MSI_FLAGS,
+				&val);
+		if (err)
+			return err;
+		if (val & PCI_MSI_FLAGS_ENABLE)
+			ret |= INTERRUPT_TYPE_MSI;
+	}
+	if (dev->msix_cap) {
+		err = pci_read_config_word(dev,
+				dev->msix_cap + PCI_MSIX_FLAGS,
+				&val);
+		if (err)
+			return err;
+		if (val & PCI_MSIX_FLAGS_ENABLE)
+			ret |= INTERRUPT_TYPE_MSIX;
+	}
+	return ret;
+}
+
 void xen_pcibk_config_free_dyn_fields(struct pci_dev *dev)
 {
 	struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);

drivers/xen/xen-pciback/conf_space.h

@@ -65,6 +65,11 @@ struct config_field_entry {
 	void *data;
 };
 
+#define INTERRUPT_TYPE_NONE (1<<0)
+#define INTERRUPT_TYPE_INTX (1<<1)
+#define INTERRUPT_TYPE_MSI  (1<<2)
+#define INTERRUPT_TYPE_MSIX (1<<3)
+
 extern bool xen_pcibk_permissive;
 
 #define OFFSET(cfg_entry) ((cfg_entry)->base_offset+(cfg_entry)->field->offset)
@@ -126,4 +131,6 @@ int xen_pcibk_config_capability_init(void);
 int xen_pcibk_config_header_add_fields(struct pci_dev *dev);
 int xen_pcibk_config_capability_add_fields(struct pci_dev *dev);
 
+int xen_pcibk_get_interrupt_type(struct pci_dev *dev);
+
 #endif				/* __XEN_PCIBACK_CONF_SPACE_H__ */

drivers/xen/xen-pciback/conf_space_capability.c

@@ -189,6 +189,85 @@ static const struct config_field caplist_pm[] = {
 	{}
 };
 
+static struct msi_msix_field_config {
+	u16          enable_bit; /* bit for enabling MSI/MSI-X */
+	unsigned int int_type;   /* interrupt type for exclusiveness check */
+} msi_field_config = {
+	.enable_bit	= PCI_MSI_FLAGS_ENABLE,
+	.int_type	= INTERRUPT_TYPE_MSI,
+}, msix_field_config = {
+	.enable_bit	= PCI_MSIX_FLAGS_ENABLE,
+	.int_type	= INTERRUPT_TYPE_MSIX,
+};
+
+static void *msi_field_init(struct pci_dev *dev, int offset)
+{
+	return &msi_field_config;
+}
+
+static void *msix_field_init(struct pci_dev *dev, int offset)
+{
+	return &msix_field_config;
+}
+
+static int msi_msix_flags_write(struct pci_dev *dev, int offset, u16 new_value,
+				void *data)
+{
+	int err;
+	u16 old_value;
+	const struct msi_msix_field_config *field_config = data;
+	const struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
+
+	if (xen_pcibk_permissive || dev_data->permissive)
+		goto write;
+
+	err = pci_read_config_word(dev, offset, &old_value);
+	if (err)
+		return err;
+
+	if (new_value == old_value)
+		return 0;
+
+	if (!dev_data->allow_interrupt_control ||
+	    (new_value ^ old_value) & ~field_config->enable_bit)
+		return PCIBIOS_SET_FAILED;
+
+	if (new_value & field_config->enable_bit) {
+		/* don't allow enabling together with other interrupt types */
+		int int_type = xen_pcibk_get_interrupt_type(dev);
+
+		if (int_type == INTERRUPT_TYPE_NONE ||
+		    int_type == field_config->int_type)
+			goto write;
+		return PCIBIOS_SET_FAILED;
+	}
+
+write:
+	return pci_write_config_word(dev, offset, new_value);
+}
+
+static const struct config_field caplist_msix[] = {
+	{
+		.offset    = PCI_MSIX_FLAGS,
+		.size      = 2,
+		.init      = msix_field_init,
+		.u.w.read  = xen_pcibk_read_config_word,
+		.u.w.write = msi_msix_flags_write,
+	},
+	{}
+};
+
+static const struct config_field caplist_msi[] = {
+	{
+		.offset    = PCI_MSI_FLAGS,
+		.size      = 2,
+		.init      = msi_field_init,
+		.u.w.read  = xen_pcibk_read_config_word,
+		.u.w.write = msi_msix_flags_write,
+	},
+	{}
+};
+
 static struct xen_pcibk_config_capability xen_pcibk_config_capability_pm = {
 	.capability = PCI_CAP_ID_PM,
 	.fields = caplist_pm,
@@ -197,11 +276,21 @@ static struct xen_pcibk_config_capability xen_pcibk_config_capability_vpd = {
 	.capability = PCI_CAP_ID_VPD,
 	.fields = caplist_vpd,
 };
+static struct xen_pcibk_config_capability xen_pcibk_config_capability_msi = {
+	.capability = PCI_CAP_ID_MSI,
+	.fields = caplist_msi,
+};
+static struct xen_pcibk_config_capability xen_pcibk_config_capability_msix = {
+	.capability = PCI_CAP_ID_MSIX,
+	.fields = caplist_msix,
+};
 
 int xen_pcibk_config_capability_init(void)
 {
 	register_capability(&xen_pcibk_config_capability_vpd);
 	register_capability(&xen_pcibk_config_capability_pm);
+	register_capability(&xen_pcibk_config_capability_msi);
+	register_capability(&xen_pcibk_config_capability_msix);
 
 	return 0;
 }

drivers/xen/xen-pciback/conf_space_header.c

@@ -117,6 +117,25 @@ static int command_write(struct pci_dev *dev, int offset, u16 value, void *data)
 		pci_clear_mwi(dev);
 	}
 
+	if (dev_data && dev_data->allow_interrupt_control) {
+		if ((cmd->val ^ value) & PCI_COMMAND_INTX_DISABLE) {
+			if (value & PCI_COMMAND_INTX_DISABLE) {
+				pci_intx(dev, 0);
+			} else {
+				/* Do not allow enabling INTx together with MSI or MSI-X. */
+				switch (xen_pcibk_get_interrupt_type(dev)) {
+				case INTERRUPT_TYPE_NONE:
+					pci_intx(dev, 1);
+					break;
+				case INTERRUPT_TYPE_INTX:
+					break;
+				default:
+					return PCIBIOS_SET_FAILED;
+				}
+			}
+		}
+	}
+
 	cmd->val = value;
 
 	if (!xen_pcibk_permissive && (!dev_data || !dev_data->permissive))

drivers/xen/xen-pciback/pci_stub.c

@@ -304,6 +304,8 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
 	xen_pcibk_config_reset_dev(dev);
 	xen_pcibk_config_free_dyn_fields(dev);
 
+	dev_data->allow_interrupt_control = 0;
+
 	xen_unregister_device_domain_owner(dev);
 
 	spin_lock_irqsave(&found_psdev->lock, flags);
@@ -1431,6 +1433,65 @@ static ssize_t permissive_show(struct device_driver *drv, char *buf)
 }
 static DRIVER_ATTR_RW(permissive);
 
+static ssize_t allow_interrupt_control_store(struct device_driver *drv,
+					     const char *buf, size_t count)
+{
+	int domain, bus, slot, func;
+	int err;
+	struct pcistub_device *psdev;
+	struct xen_pcibk_dev_data *dev_data;
+
+	err = str_to_slot(buf, &domain, &bus, &slot, &func);
+	if (err)
+		goto out;
+
+	psdev = pcistub_device_find(domain, bus, slot, func);
+	if (!psdev) {
+		err = -ENODEV;
+		goto out;
+	}
+
+	dev_data = pci_get_drvdata(psdev->dev);
+	/* the driver data for a device should never be null at this point */
+	if (!dev_data) {
+		err = -ENXIO;
+		goto release;
+	}
+	dev_data->allow_interrupt_control = 1;
+release:
+	pcistub_device_put(psdev);
+out:
+	if (!err)
+		err = count;
+	return err;
+}
+
+static ssize_t allow_interrupt_control_show(struct device_driver *drv,
+					    char *buf)
+{
+	struct pcistub_device *psdev;
+	struct xen_pcibk_dev_data *dev_data;
+	size_t count = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pcistub_devices_lock, flags);
+	list_for_each_entry(psdev, &pcistub_devices, dev_list) {
+		if (count >= PAGE_SIZE)
+			break;
+		if (!psdev->dev)
+			continue;
+		dev_data = pci_get_drvdata(psdev->dev);
+		if (!dev_data || !dev_data->allow_interrupt_control)
+			continue;
+		count +=
+		    scnprintf(buf + count, PAGE_SIZE - count, "%s\n",
+			      pci_name(psdev->dev));
+	}
+	spin_unlock_irqrestore(&pcistub_devices_lock, flags);
+	return count;
+}
+static DRIVER_ATTR_RW(allow_interrupt_control);
+
 static void pcistub_exit(void)
 {
 	driver_remove_file(&xen_pcibk_pci_driver.driver, &driver_attr_new_slot);
@@ -1440,6 +1501,8 @@ static void pcistub_exit(void)
 	driver_remove_file(&xen_pcibk_pci_driver.driver, &driver_attr_quirks);
 	driver_remove_file(&xen_pcibk_pci_driver.driver,
 			   &driver_attr_permissive);
+	driver_remove_file(&xen_pcibk_pci_driver.driver,
+			   &driver_attr_allow_interrupt_control);
 	driver_remove_file(&xen_pcibk_pci_driver.driver,
 			   &driver_attr_irq_handlers);
 	driver_remove_file(&xen_pcibk_pci_driver.driver,
@@ -1530,6 +1593,9 @@ static int __init pcistub_init(void)
 	if (!err)
 		err = driver_create_file(&xen_pcibk_pci_driver.driver,
 					 &driver_attr_permissive);
+	if (!err)
+		err = driver_create_file(&xen_pcibk_pci_driver.driver,
+					 &driver_attr_allow_interrupt_control);
 
 	if (!err)
 		err = driver_create_file(&xen_pcibk_pci_driver.driver,

drivers/xen/xen-pciback/pciback.h

@@ -45,6 +45,7 @@ struct xen_pcibk_dev_data {
 	struct list_head config_fields;
 	struct pci_saved_state *pci_saved_state;
 	unsigned int permissive:1;
+	unsigned int allow_interrupt_control:1;
 	unsigned int warned_on_write:1;
 	unsigned int enable_intx:1;
 	unsigned int isr_on:1; /* Whether the IRQ handler is installed. */

drivers/xen/xenbus/xenbus_probe.c

@@ -239,7 +239,9 @@ int xenbus_dev_probe(struct device *_dev)
 		goto fail;
 	}
 
+	spin_lock(&dev->reclaim_lock);
 	err = drv->probe(dev, id);
+	spin_unlock(&dev->reclaim_lock);
 	if (err)
 		goto fail_put;
 
@@ -268,8 +270,11 @@ int xenbus_dev_remove(struct device *_dev)
 
 	free_otherend_watch(dev);
 
-	if (drv->remove)
+	if (drv->remove) {
+		spin_lock(&dev->reclaim_lock);
 		drv->remove(dev);
+		spin_unlock(&dev->reclaim_lock);
+	}
 
 	module_put(drv->driver.owner);
 
@@ -468,6 +473,7 @@ int xenbus_probe_node(struct xen_bus_type *bus,
 		goto fail;
 
 	dev_set_name(&xendev->dev, "%s", devname);
+	spin_lock_init(&xendev->reclaim_lock);
 
 	/* Register with generic device framework. */
 	err = device_register(&xendev->dev);

drivers/xen/xenbus/xenbus_probe_backend.c

@@ -247,6 +247,41 @@ static int backend_probe_and_watch(struct notifier_block *notifier,
 	return NOTIFY_DONE;
 }
 
+static int backend_reclaim_memory(struct device *dev, void *data)
+{
+	const struct xenbus_driver *drv;
+	struct xenbus_device *xdev;
+
+	if (!dev->driver)
+		return 0;
+	drv = to_xenbus_driver(dev->driver);
+	if (drv && drv->reclaim_memory) {
+		xdev = to_xenbus_device(dev);
+		if (!spin_trylock(&xdev->reclaim_lock))
+			return 0;
+		drv->reclaim_memory(xdev);
+		spin_unlock(&xdev->reclaim_lock);
+	}
+	return 0;
+}
+
+/*
+ * Returns 0 always because we are using shrinker to only detect memory
+ * pressure.
+ */
+static unsigned long backend_shrink_memory_count(struct shrinker *shrinker,
+				struct shrink_control *sc)
+{
+	bus_for_each_dev(&xenbus_backend.bus, NULL, NULL,
+			backend_reclaim_memory);
+	return 0;
+}
+
+static struct shrinker backend_memory_shrinker = {
+	.count_objects = backend_shrink_memory_count,
+	.seeks = DEFAULT_SEEKS,
+};
+
 static int __init xenbus_probe_backend_init(void)
 {
 	static struct notifier_block xenstore_notifier = {
@@ -263,6 +298,9 @@ static int __init xenbus_probe_backend_init(void)
 
 	register_xenstore_notifier(&xenstore_notifier);
 
+	if (register_shrinker(&backend_memory_shrinker))
+		pr_warn("shrinker registration failed\n");
+
 	return 0;
 }
 subsys_initcall(xenbus_probe_backend_init);