iommu/s390: Add iommu api for s390 pci devices

This adds an IOMMU API implementation for s390 PCI devices.

Reviewed-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

3 files changed, 345 insertions, 0 deletions

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index d9da766719c8..5feb70a91a8c 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -369,4 +369,11 @@ config ARM_SMMU_V3
 	  Say Y here if your system includes an IOMMU device implementing
 	  the ARM SMMUv3 architecture.
 
+config S390_IOMMU
+	def_bool y if S390 && PCI
+	depends on S390 && PCI
+	select IOMMU_API
+	help
+	  Support for the IOMMU API for s390 PCI devices.
+
 endif # IOMMU_SUPPORT
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index c6dcc513d711..a2056d35420b 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -23,3 +23,4 @@ obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
 obj-$(CONFIG_SHMOBILE_IOMMU) += shmobile-iommu.o
 obj-$(CONFIG_SHMOBILE_IPMMU) += shmobile-ipmmu.o
 obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o
+obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
new file mode 100644
index 000000000000..cbe198cb3699
--- /dev/null
+++ b/drivers/iommu/s390-iommu.c
@@ -0,0 +1,337 @@
+/*
+ * IOMMU API for s390 PCI devices
+ *
+ * Copyright IBM Corp. 2015
+ * Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
+ */
+
+#include <linux/pci.h>
+#include <linux/iommu.h>
+#include <linux/iommu-helper.h>
+#include <linux/pci.h>
+#include <linux/sizes.h>
+#include <asm/pci_dma.h>
+
+/*
+ * Physically contiguous memory regions can be mapped with 4 KiB alignment,
+ * we allow all page sizes that are an order of 4KiB (no special large page
+ * support so far).
+ */
+#define S390_IOMMU_PGSIZES	(~0xFFFUL)
+
+struct s390_domain {
+	struct iommu_domain	domain;
+	struct list_head	devices;
+	unsigned long		*dma_table;
+	spinlock_t		dma_table_lock;
+	spinlock_t		list_lock;
+};
+
+struct s390_domain_device {
+	struct list_head	list;
+	struct zpci_dev		*zdev;
+};
+
+static struct s390_domain *to_s390_domain(struct iommu_domain *dom)
+{
+	return container_of(dom, struct s390_domain, domain);
+}
+
+static bool s390_iommu_capable(enum iommu_cap cap)
+{
+	switch (cap) {
+	case IOMMU_CAP_CACHE_COHERENCY:
+		return true;
+	case IOMMU_CAP_INTR_REMAP:
+		return true;
+	default:
+		return false;
+	}
+}
+
+struct iommu_domain *s390_domain_alloc(unsigned domain_type)
+{
+	struct s390_domain *s390_domain;
+
+	if (domain_type != IOMMU_DOMAIN_UNMANAGED)
+		return NULL;
+
+	s390_domain = kzalloc(sizeof(*s390_domain), GFP_KERNEL);
+	if (!s390_domain)
+		return NULL;
+
+	s390_domain->dma_table = dma_alloc_cpu_table();
+	if (!s390_domain->dma_table) {
+		kfree(s390_domain);
+		return NULL;
+	}
+
+	spin_lock_init(&s390_domain->dma_table_lock);
+	spin_lock_init(&s390_domain->list_lock);
+	INIT_LIST_HEAD(&s390_domain->devices);
+
+	return &s390_domain->domain;
+}
+
+void s390_domain_free(struct iommu_domain *domain)
+{
+	struct s390_domain *s390_domain = to_s390_domain(domain);
+
+	dma_cleanup_tables(s390_domain->dma_table);
+	kfree(s390_domain);
+}
+
+static int s390_iommu_attach_device(struct iommu_domain *domain,
+				    struct device *dev)
+{
+	struct s390_domain *s390_domain = to_s390_domain(domain);
+	struct zpci_dev *zdev = to_pci_dev(dev)->sysdata;
+	struct s390_domain_device *domain_device;
+	unsigned long flags;
+	int rc;
+
+	if (!zdev)
+		return -ENODEV;
+
+	domain_device = kzalloc(sizeof(*domain_device), GFP_KERNEL);
+	if (!domain_device)
+		return -ENOMEM;
+
+	if (zdev->dma_table)
+		zpci_dma_exit_device(zdev);
+
+	zdev->dma_table = s390_domain->dma_table;
+	rc = zpci_register_ioat(zdev, 0, zdev->start_dma + PAGE_OFFSET,
+				zdev->start_dma + zdev->iommu_size - 1,
+				(u64) zdev->dma_table);
+	if (rc)
+		goto out_restore;
+
+	spin_lock_irqsave(&s390_domain->list_lock, flags);
+	/* First device defines the DMA range limits */
+	if (list_empty(&s390_domain->devices)) {
+		domain->geometry.aperture_start = zdev->start_dma;
+		domain->geometry.aperture_end = zdev->end_dma;
+		domain->geometry.force_aperture = true;
+	/* Allow only devices with identical DMA range limits */
+	} else if (domain->geometry.aperture_start != zdev->start_dma ||
+		   domain->geometry.aperture_end != zdev->end_dma) {
+		rc = -EINVAL;
+		spin_unlock_irqrestore(&s390_domain->list_lock, flags);
+		goto out_restore;
+	}
+	domain_device->zdev = zdev;
+	zdev->s390_domain = s390_domain;
+	list_add(&domain_device->list, &s390_domain->devices);
+	spin_unlock_irqrestore(&s390_domain->list_lock, flags);
+
+	return 0;
+
+out_restore:
+	zpci_dma_init_device(zdev);
+	kfree(domain_device);
+
+	return rc;
+}
+
+static void s390_iommu_detach_device(struct iommu_domain *domain,
+				     struct device *dev)
+{
+	struct s390_domain *s390_domain = to_s390_domain(domain);
+	struct zpci_dev *zdev = to_pci_dev(dev)->sysdata;
+	struct s390_domain_device *domain_device, *tmp;
+	unsigned long flags;
+	int found = 0;
+
+	if (!zdev)
+		return;
+
+	spin_lock_irqsave(&s390_domain->list_lock, flags);
+	list_for_each_entry_safe(domain_device, tmp, &s390_domain->devices,
+				 list) {
+		if (domain_device->zdev == zdev) {
+			list_del(&domain_device->list);
+			kfree(domain_device);
+			found = 1;
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&s390_domain->list_lock, flags);
+
+	if (found) {
+		zdev->s390_domain = NULL;
+		zpci_unregister_ioat(zdev, 0);
+		zpci_dma_init_device(zdev);
+	}
+}
+
+static int s390_iommu_add_device(struct device *dev)
+{
+	struct iommu_group *group;
+	int rc;
+
+	group = iommu_group_get(dev);
+	if (!group) {
+		group = iommu_group_alloc();
+		if (IS_ERR(group))
+			return PTR_ERR(group);
+	}
+
+	rc = iommu_group_add_device(group, dev);
+	iommu_group_put(group);
+
+	return rc;
+}
+
+static void s390_iommu_remove_device(struct device *dev)
+{
+	struct zpci_dev *zdev = to_pci_dev(dev)->sysdata;
+	struct iommu_domain *domain;
+
+	/*
+	 * This is a workaround for a scenario where the IOMMU API common code
+	 * "forgets" to call the detach_dev callback: After binding a device
+	 * to vfio-pci and completing the VFIO_SET_IOMMU ioctl (which triggers
+	 * the attach_dev), removing the device via
+	 * "echo 1 > /sys/bus/pci/devices/.../remove" won't trigger detach_dev,
+	 * only remove_device will be called via the BUS_NOTIFY_REMOVED_DEVICE
+	 * notifier.
+	 *
+	 * So let's call detach_dev from here if it hasn't been called before.
+	 */
+	if (zdev && zdev->s390_domain) {
+		domain = iommu_get_domain_for_dev(dev);
+		if (domain)
+			s390_iommu_detach_device(domain, dev);
+	}
+
+	iommu_group_remove_device(dev);
+}
+
+static int s390_iommu_update_trans(struct s390_domain *s390_domain,
+				   unsigned long pa, dma_addr_t dma_addr,
+				   size_t size, int flags)
+{
+	struct s390_domain_device *domain_device;
+	u8 *page_addr = (u8 *) (pa & PAGE_MASK);
+	dma_addr_t start_dma_addr = dma_addr;
+	unsigned long irq_flags, nr_pages, i;
+	int rc = 0;
+
+	if (dma_addr < s390_domain->domain.geometry.aperture_start ||
+	    dma_addr + size > s390_domain->domain.geometry.aperture_end)
+		return -EINVAL;
+
+	nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	if (!nr_pages)
+		return 0;
+
+	spin_lock_irqsave(&s390_domain->dma_table_lock, irq_flags);
+	for (i = 0; i < nr_pages; i++) {
+		dma_update_cpu_trans(s390_domain->dma_table, page_addr,
+				     dma_addr, flags);
+		page_addr += PAGE_SIZE;
+		dma_addr += PAGE_SIZE;
+	}
+
+	spin_lock(&s390_domain->list_lock);
+	list_for_each_entry(domain_device, &s390_domain->devices, list) {
+		rc = zpci_refresh_trans((u64) domain_device->zdev->fh << 32,
+					start_dma_addr, nr_pages * PAGE_SIZE);
+		if (rc)
+			break;
+	}
+	spin_unlock(&s390_domain->list_lock);
+	spin_unlock_irqrestore(&s390_domain->dma_table_lock, irq_flags);
+
+	return rc;
+}
+
+static int s390_iommu_map(struct iommu_domain *domain, unsigned long iova,
+			  phys_addr_t paddr, size_t size, int prot)
+{
+	struct s390_domain *s390_domain = to_s390_domain(domain);
+	int flags = ZPCI_PTE_VALID, rc = 0;
+
+	if (!(prot & IOMMU_READ))
+		return -EINVAL;
+
+	if (!(prot & IOMMU_WRITE))
+		flags |= ZPCI_TABLE_PROTECTED;
+
+	rc = s390_iommu_update_trans(s390_domain, (unsigned long) paddr, iova,
+				     size, flags);
+
+	return rc;
+}
+
+static phys_addr_t s390_iommu_iova_to_phys(struct iommu_domain *domain,
+					   dma_addr_t iova)
+{
+	struct s390_domain *s390_domain = to_s390_domain(domain);
+	unsigned long *sto, *pto, *rto, flags;
+	unsigned int rtx, sx, px;
+	phys_addr_t phys = 0;
+
+	if (iova < domain->geometry.aperture_start ||
+	    iova > domain->geometry.aperture_end)
+		return 0;
+
+	rtx = calc_rtx(iova);
+	sx = calc_sx(iova);
+	px = calc_px(iova);
+	rto = s390_domain->dma_table;
+
+	spin_lock_irqsave(&s390_domain->dma_table_lock, flags);
+	if (rto && reg_entry_isvalid(rto[rtx])) {
+		sto = get_rt_sto(rto[rtx]);
+		if (sto && reg_entry_isvalid(sto[sx])) {
+			pto = get_st_pto(sto[sx]);
+			if (pto && pt_entry_isvalid(pto[px]))
+				phys = pto[px] & ZPCI_PTE_ADDR_MASK;
+		}
+	}
+	spin_unlock_irqrestore(&s390_domain->dma_table_lock, flags);
+
+	return phys;
+}
+
+static size_t s390_iommu_unmap(struct iommu_domain *domain,
+			       unsigned long iova, size_t size)
+{
+	struct s390_domain *s390_domain = to_s390_domain(domain);
+	int flags = ZPCI_PTE_INVALID;
+	phys_addr_t paddr;
+	int rc;
+
+	paddr = s390_iommu_iova_to_phys(domain, iova);
+	if (!paddr)
+		return 0;
+
+	rc = s390_iommu_update_trans(s390_domain, (unsigned long) paddr, iova,
+				     size, flags);
+	if (rc)
+		return 0;
+
+	return size;
+}
+
+static struct iommu_ops s390_iommu_ops = {
+	.capable = s390_iommu_capable,
+	.domain_alloc = s390_domain_alloc,
+	.domain_free = s390_domain_free,
+	.attach_dev = s390_iommu_attach_device,
+	.detach_dev = s390_iommu_detach_device,
+	.map = s390_iommu_map,
+	.unmap = s390_iommu_unmap,
+	.iova_to_phys = s390_iommu_iova_to_phys,
+	.add_device = s390_iommu_add_device,
+	.remove_device = s390_iommu_remove_device,
+	.pgsize_bitmap = S390_IOMMU_PGSIZES,
+};
+
+static int __init s390_iommu_init(void)
+{
+	return bus_set_iommu(&pci_bus_type, &s390_iommu_ops);
+}
+subsys_initcall(s390_iommu_init);