[PATCH] vfio-powerpc: enabled and supported on power

[Alexey Kardashevskiy]

The patch introduces support of VFIO on POWER.

The patch consists of:

1. IOMMU driver for VFIO.
It does not use IOMMU API at all, instead it calls POWER
IOMMU API directly (ppc_md callbacks).

2. A piece of code (module_init) which creates IOMMU groups.
TBD: what is a better place for it?

The patch is made on top of
git://github.com/awilliam/linux-vfio.git iommu-group-vfio-20120523
(which is iommu-group-vfio-20120521 + some fixes)

Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
---
 arch/powerpc/Kconfig             |    6 +
 arch/powerpc/include/asm/iommu.h |    3 +
 arch/powerpc/kernel/Makefile     |    1 +
 arch/powerpc/kernel/iommu_vfio.c |  371 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 381 insertions(+), 0 deletions(-)
 create mode 100644 arch/powerpc/kernel/iommu_vfio.c

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index feab3ba..13d12ac 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -319,6 +319,12 @@ config 8XX_MINIMAL_FPEMU
 config IOMMU_HELPER
 	def_bool PPC64
 
+config IOMMU_VFIO
+	select IOMMU_API
+	depends on PPC64
+	tristate "Enable IOMMU chardev to support user-space PCI"
+	default n
+
 config SWIOTLB
 	bool "SWIOTLB support"
 	default n
diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 957a83f..c64bce7 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -66,6 +66,9 @@ struct iommu_table {
 	unsigned long  it_halfpoint; /* Breaking point for small/large allocs */
 	spinlock_t     it_lock;      /* Protects it_map */
 	unsigned long *it_map;       /* A simple allocation bitmap for now */
+#ifdef CONFIG_IOMMU_API
+	struct iommu_group *it_group;
+#endif
 };
 
 struct scatterlist;
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index f5808a3..7cfd68e 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -90,6 +90,7 @@ obj-$(CONFIG_RELOCATABLE_PPC32)	+= reloc_32.o
 
 obj-$(CONFIG_PPC32)		+= entry_32.o setup_32.o
 obj-$(CONFIG_PPC64)		+= dma-iommu.o iommu.o
+obj-$(CONFIG_IOMMU_VFIO)	+= iommu_vfio.o
 obj-$(CONFIG_KGDB)		+= kgdb.o
 obj-$(CONFIG_PPC_OF_BOOT_TRAMPOLINE)	+= prom_init.o
 obj-$(CONFIG_MODULES)		+= ppc_ksyms.o
diff --git a/arch/powerpc/kernel/iommu_vfio.c b/arch/powerpc/kernel/iommu_vfio.c
new file mode 100644
index 0000000..68a93dd
--- /dev/null
+++ b/arch/powerpc/kernel/iommu_vfio.c
@@ -0,0 +1,371 @@
+/*
+ * VFIO: IOMMU DMA mapping support for TCE on POWER
+ *
+ * Copyright (C) 2012 IBM Corp.  All rights reserved.
+ *     Author: Alexey Kardashevskiy <aik@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Derived from original vfio_iommu_x86.c:
+ * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
+ *     Author: Alex Williamson <alex.williamson@xxxxxxxxxx>
+ */
+
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/vfio.h>
+#include <linux/err.h>
+#include <linux/spinlock.h>
+#include <asm/iommu.h>
+
+#define DRIVER_VERSION  "0.1"
+#define DRIVER_AUTHOR   "aik@xxxxxxxxx"
+#define DRIVER_DESC     "POWER IOMMU chardev for VFIO"
+
+#define IOMMU_CHECK_EXTENSION	_IO(VFIO_TYPE, VFIO_BASE + 1)
+
+/* -------- API for POWERPC IOMMU -------- */
+
+#define POWERPC_IOMMU		2
+
+struct tce_iommu_info {
+	__u32 argsz;
+	__u32 dma32_window_start;
+	__u32 dma32_window_size;
+};
+
+#define POWERPC_IOMMU_GET_INFO	_IO(VFIO_TYPE, VFIO_BASE + 12)
+
+struct tce_iommu_dma_map {
+	__u32 argsz;
+	__u64 va;
+	__u64 dmaaddr;
+};
+
+#define POWERPC_IOMMU_MAP_DMA	_IO(VFIO_TYPE, VFIO_BASE + 13)
+#define POWERPC_IOMMU_UNMAP_DMA	_IO(VFIO_TYPE, VFIO_BASE + 14)
+
+/* ***************************************************************** */
+
+struct tce_iommu {
+	struct iommu_table *tbl;
+};
+
+static int tce_iommu_attach_group(void *iommu_data,
+		struct iommu_group *iommu_group)
+{
+	struct tce_iommu *tceiommu = iommu_data;
+
+	if (tceiommu->tbl) {
+		printk(KERN_ERR "Only one group per IOMMU instance is allowed\n");
+		return -EFAULT;
+	}
+	tceiommu->tbl = iommu_group_get_iommudata(iommu_group);
+
+	return 0;
+}
+
+static void tce_iommu_detach_group(void *iommu_data,
+		struct iommu_group *iommu_group)
+{
+	struct tce_iommu *tceiommu = iommu_data;
+
+	if (!tceiommu->tbl) {
+		printk(KERN_ERR "IOMMU already released\n");
+		return;
+	}
+	tceiommu->tbl = NULL;
+}
+
+static void *tce_iommu_open(unsigned long arg)
+{
+	struct tce_iommu *tceiommu;
+
+	if (arg != POWERPC_IOMMU)
+		return ERR_PTR(-EINVAL);
+
+	tceiommu = kzalloc(sizeof(*tceiommu), GFP_KERNEL);
+	if (!tceiommu)
+		return ERR_PTR(-ENOMEM);
+
+	return tceiommu;
+}
+
+static void tce_iommu_release(void *iommu_data)
+{
+	struct tce_iommu *tceiommu = iommu_data;
+	kfree(tceiommu);
+}
+
+static int tce_iommu_map(struct iommu_table *tbl, unsigned long iova,
+		   phys_addr_t paddr)
+{
+	unsigned long entry, flags;
+	int build_fail;
+
+	spin_lock_irqsave(&(tbl->it_lock), flags);
+	entry = iova >> IOMMU_PAGE_SHIFT;
+	build_fail = ppc_md.tce_build(tbl, entry, 1/*pages*/,
+			(unsigned long)paddr & IOMMU_PAGE_MASK,
+			DMA_BIDIRECTIONAL, NULL/*attrs*/);
+
+	/* ppc_md.tce_build() only returns non-zero for transient errors.
+	 * Clean up the table bitmap in this case and return
+	 * DMA_ERROR_CODE. For all other errors the functionality is
+	 * not altered.
+	 */
+	if (unlikely(build_fail)) {
+		printk("Failed to add TCE\n");
+		spin_unlock_irqrestore(&(tbl->it_lock), flags);
+		return -EFAULT;
+	}
+	/* Flush/invalidate TLB caches if necessary */
+	if (ppc_md.tce_flush)
+		ppc_md.tce_flush(tbl);
+
+	spin_unlock_irqrestore(&(tbl->it_lock), flags);
+
+	/* Make sure updates are seen by hardware */
+	mb();
+
+	return 0;
+}
+
+static void tce_iommu_unmap(struct iommu_table *tbl, unsigned long iova)
+{
+	unsigned long entry, flags;
+	entry = iova >> IOMMU_PAGE_SHIFT;
+
+	spin_lock_irqsave(&(tbl->it_lock), flags);
+	ppc_md.tce_free(tbl, entry, 1);
+	/* Flush/invalidate TLB caches if necessary */
+	if (ppc_md.tce_flush)
+		ppc_md.tce_flush(tbl);
+
+	spin_unlock_irqrestore(&(tbl->it_lock), flags);
+
+	/* Make sure updates are seen by hardware */
+	mb();
+}
+
+static phys_addr_t tce_iommu_iova_to_va(struct iommu_table *tbl,
+		unsigned long iova)
+{
+	unsigned long entry = iova >> IOMMU_PAGE_SHIFT;
+	phys_addr_t ret = 0;
+
+	if (ppc_md.tce_get)
+		ret = ppc_md.tce_get(tbl, entry);
+
+	return ret;
+}
+
+static struct page *tceaddr_to_page(void *addr)
+{
+	return pfn_to_page(__pa(addr) >> PAGE_SHIFT);
+}
+
+static long tce_dmamap_page(struct iommu_table *tbl,
+		uint64_t va, uint64_t dmaaddr)
+{
+	int ret = -EFAULT;
+	phys_addr_t addr;
+	struct page *page[1];
+	int iswrite = 1;
+	void *kva;
+
+	if (NULL == tbl) {
+		printk(KERN_ERR"tce_iommu: (map) IOMMU table has not "
+				"been initialized yet!\n");
+		return -EFAULT;
+	}
+	addr = tce_iommu_iova_to_va(tbl, dmaaddr);
+	if (addr) {
+		printk(KERN_WARNING"tce_iommu: already mapped va=%llx "
+				"da=%llx addr=%llx\n",
+				va, dmaaddr, addr);
+		/*TODO: unmap! */
+	}
+
+	ret = get_user_pages_fast(va, 1, iswrite, page);
+	if (1 != ret) {
+		printk(KERN_ERR"tce_iommu: get_user_pages_fast failed "
+				"va=%llx da=%llx addr=%llx ret=%d\n",
+				va, dmaaddr, addr, ret);
+		return -EFAULT;
+	}
+	ret = -EFAULT;
+	kva = (void *) page_address(page[0]);
+	if (kva) {
+		ret = tce_iommu_map(tbl, dmaaddr, (phys_addr_t) kva);
+	}
+	if (ret) {
+		printk(KERN_ERR"tce_iommu: tce_iommu_map va=%llx "
+				"da=%llx kva=%p\n",
+				va, dmaaddr, kva);
+		if (iswrite)
+			SetPageDirty(page[0]);
+		put_page(page[0]);
+	}
+
+	return ret;
+}
+
+static long tce_dmaunmap_page(struct iommu_table *tbl, uint64_t dmaaddr)
+{
+	int ret = 0;
+	phys_addr_t addr;
+	struct page *page;
+
+	if (NULL == tbl) {
+		printk(KERN_ERR"tce_iommu: (unmap) IOMMU table has not been "
+				"initialized yet!\n");
+		return -EFAULT;
+	}
+	addr = tce_iommu_iova_to_va(tbl, dmaaddr);
+	if (addr) {
+		page = tceaddr_to_page((void*)addr);
+		if (!page) {
+			printk(KERN_ERR"DMAUNMAP error: pfn_to_page(%llx) "
+					"failed\n", addr);
+			ret = -EFAULT;
+		} else {
+			SetPageDirty(page);
+			put_page(page);
+		}
+	}
+	tce_iommu_unmap(tbl, dmaaddr);
+	if (ret)
+		printk(KERN_ERR"Failed to DMAUNMAP: da=%llx pfn=%llx\n",
+				dmaaddr, addr);
+	return ret;
+}
+
+
+static long tce_iommu_ioctl(void *iommu_data,
+				 unsigned int cmd, unsigned long arg)
+{
+	struct tce_iommu *tceiommu = iommu_data;
+	unsigned long minsz;
+
+	if (cmd == IOMMU_CHECK_EXTENSION) {
+		switch (arg) {
+		case POWERPC_IOMMU:
+			return 1;
+		default:
+			return 0;
+		}
+	} else if (cmd == POWERPC_IOMMU_GET_INFO) {
+		struct tce_iommu_info info;
+
+		minsz = offsetofend(struct tce_iommu_info, dma32_window_size);
+
+		if (copy_from_user(&info, (void __user *)arg, minsz))
+			return -EFAULT;
+
+		if (info.argsz < minsz)
+			return -EINVAL;
+
+		info.dma32_window_start =
+				tceiommu->tbl->it_offset << IOMMU_PAGE_SHIFT;
+		info.dma32_window_size =
+				tceiommu->tbl->it_size << IOMMU_PAGE_SHIFT;
+
+		return copy_to_user((void __user *)arg, &info, minsz);
+
+	} else if (cmd == POWERPC_IOMMU_MAP_DMA) {
+		struct tce_iommu_dma_map map;
+
+		minsz = offsetofend(struct tce_iommu_dma_map, dmaaddr);
+
+		if (copy_from_user(&map, (void __user *)arg, minsz))
+			return -EFAULT;
+
+		if (map.argsz < minsz)
+			return -EINVAL;
+
+		return tce_dmamap_page(tceiommu->tbl, map.va, map.dmaaddr);
+
+	} else if (cmd == POWERPC_IOMMU_UNMAP_DMA) {
+		struct tce_iommu_dma_map unmap;
+
+		minsz = offsetofend(struct tce_iommu_dma_map, dmaaddr);
+
+		if (copy_from_user(&unmap, (void __user *)arg, minsz))
+			return -EFAULT;
+
+		if (unmap.argsz < minsz)
+			return -EINVAL;
+
+		return tce_dmaunmap_page(tceiommu->tbl, unmap.dmaaddr);
+	}
+
+	return -ENOTTY;
+}
+
+const struct vfio_iommu_driver_ops tce_iommu_driver_ops = {
+	.name		= "vfio-iommu-powerpc",
+	.owner		= THIS_MODULE,
+	.open		= tce_iommu_open,
+	.release	= tce_iommu_release,
+	.ioctl		= tce_iommu_ioctl,
+	.attach_group	= tce_iommu_attach_group,
+	.detach_group	= tce_iommu_detach_group,
+};
+
+static int __init tce_iommu_init(void)
+{
+	struct pci_dev *pdev = NULL;
+	struct iommu_table *tbl = NULL;
+	struct iommu_group *grp = NULL;
+	int ret = 0;
+
+	/* TODO: Do this for all devices, not just for PCI */
+	for_each_pci_dev(pdev) {
+
+		tbl = get_iommu_table_base(&pdev->dev);
+		if (NULL == tbl) {
+			printk("Skipping device %s\n", pdev->dev.kobj.name);
+			continue;
+		}
+		if (!tbl->it_group) {
+			struct iommu_group *tmp = iommu_group_alloc();
+			if (IS_ERR(tmp)) {
+				printk("Failed to create new IOMMU group, "
+						"ret = %ld\n", PTR_ERR(tmp));
+				break;
+			}
+			tbl->it_group = tmp;
+			iommu_group_set_iommudata(tmp, tbl, NULL);
+		}
+
+		grp = iommu_group_get(&pdev->dev);
+		if (!grp) {
+			ret = iommu_group_add_device(tbl->it_group, &pdev->dev);
+			if (ret < 0)
+				printk("iommu_group_add_device(%s) failed "
+						"with %d\n",
+						pdev->dev.kobj.name, ret);
+		}
+	}
+
+	return vfio_register_iommu_driver(&tce_iommu_driver_ops);
+}
+
+static void __exit tce_iommu_cleanup(void)
+{
+	vfio_unregister_iommu_driver(&tce_iommu_driver_ops);
+}
+
+module_init(tce_iommu_init);
+module_exit(tce_iommu_cleanup);
+
+MODULE_VERSION(DRIVER_VERSION);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+

-- 
1.7.7.3
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