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Subject[PATCH 2/2] vfio powerpc: implemented IOMMU driver for VFIO
Date
VFIO implements platform independent stuff such as
a PCI driver, BAR access (via read/write on a file descriptor
or direct mapping when possible) and IRQ signaling.

The platform dependent part includes IOMMU initialization
and handling. This patch implements an IOMMU driver for VFIO
which does mapping/unmapping pages for the guest IO and
provides information about DMA window (required by a POWERPC
guest).

The counterpart in QEMU is required to support this functionality.

Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
drivers/vfio/Kconfig | 6 +
drivers/vfio/Makefile | 1 +
drivers/vfio/vfio_iommu_spapr_tce.c | 350 +++++++++++++++++++++++++++++++++++
include/linux/vfio.h | 26 +++
4 files changed, 383 insertions(+)
create mode 100644 drivers/vfio/vfio_iommu_spapr_tce.c

diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
index 7cd5dec..b464687 100644
--- a/drivers/vfio/Kconfig
+++ b/drivers/vfio/Kconfig
@@ -3,10 +3,16 @@ config VFIO_IOMMU_TYPE1
depends on VFIO
default n

+config VFIO_IOMMU_SPAPR_TCE
+ tristate
+ depends on VFIO && SPAPR_TCE_IOMMU
+ default n
+
menuconfig VFIO
tristate "VFIO Non-Privileged userspace driver framework"
depends on IOMMU_API
select VFIO_IOMMU_TYPE1 if X86
+ select VFIO_IOMMU_SPAPR_TCE if PPC_POWERNV
help
VFIO provides a framework for secure userspace device drivers.
See Documentation/vfio.txt for more details.
diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile
index 2398d4a..72bfabc 100644
--- a/drivers/vfio/Makefile
+++ b/drivers/vfio/Makefile
@@ -1,3 +1,4 @@
obj-$(CONFIG_VFIO) += vfio.o
obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o
+obj-$(CONFIG_VFIO_IOMMU_SPAPR_TCE) += vfio_iommu_spapr_tce.o
obj-$(CONFIG_VFIO_PCI) += pci/
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
new file mode 100644
index 0000000..806ad9f
--- /dev/null
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -0,0 +1,350 @@
+/*
+ * VFIO: IOMMU DMA mapping support for TCE on POWER
+ *
+ * Copyright (C) 2012 IBM Corp. All rights reserved.
+ * Author: Alexey Kardashevskiy <aik@ozlabs.ru>
+ *
+ * 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_type1.c:
+ * Copyright (C) 2012 Red Hat, Inc. All rights reserved.
+ * Author: Alex Williamson <alex.williamson@redhat.com>
+ */
+
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/err.h>
+#include <linux/vfio.h>
+#include <asm/iommu.h>
+
+#define DRIVER_VERSION "0.1"
+#define DRIVER_AUTHOR "aik@ozlabs.ru"
+#define DRIVER_DESC "VFIO IOMMU SPAPR TCE"
+
+static void tce_iommu_detach_group(void *iommu_data,
+ struct iommu_group *iommu_group);
+
+/*
+ * VFIO IOMMU fd for SPAPR_TCE IOMMU implementation
+ */
+
+/*
+ * This code handles mapping and unmapping of user data buffers
+ * into DMA'ble space using the IOMMU
+ */
+
+#define NPAGE_TO_SIZE(npage) ((size_t)(npage) << PAGE_SHIFT)
+
+struct vwork {
+ struct mm_struct *mm;
+ long npage;
+ struct work_struct work;
+};
+
+/* delayed decrement/increment for locked_vm */
+static void lock_acct_bg(struct work_struct *work)
+{
+ struct vwork *vwork = container_of(work, struct vwork, work);
+ struct mm_struct *mm;
+
+ mm = vwork->mm;
+ down_write(&mm->mmap_sem);
+ mm->locked_vm += vwork->npage;
+ up_write(&mm->mmap_sem);
+ mmput(mm);
+ kfree(vwork);
+}
+
+static void lock_acct(long npage)
+{
+ struct vwork *vwork;
+ struct mm_struct *mm;
+
+ if (!current->mm)
+ return; /* process exited */
+
+ if (down_write_trylock(&current->mm->mmap_sem)) {
+ current->mm->locked_vm += npage;
+ up_write(&current->mm->mmap_sem);
+ return;
+ }
+
+ /*
+ * Couldn't get mmap_sem lock, so must setup to update
+ * mm->locked_vm later. If locked_vm were atomic, we
+ * wouldn't need this silliness
+ */
+ vwork = kmalloc(sizeof(struct vwork), GFP_KERNEL);
+ if (!vwork)
+ return;
+ mm = get_task_mm(current);
+ if (!mm) {
+ kfree(vwork);
+ return;
+ }
+ INIT_WORK(&vwork->work, lock_acct_bg);
+ vwork->mm = mm;
+ vwork->npage = npage;
+ schedule_work(&vwork->work);
+}
+
+/*
+ * The container descriptor supports only a single group per container.
+ * Required by the API as the container is not supplied with the IOMMU group
+ * at the moment of initialization.
+ */
+struct tce_container {
+ struct mutex lock;
+ struct iommu_table *tbl;
+};
+
+static void *tce_iommu_open(unsigned long arg)
+{
+ struct tce_container *container;
+
+ if (arg != VFIO_SPAPR_TCE_IOMMU) {
+ pr_err("tce_vfio: Wrong IOMMU type\n");
+ return ERR_PTR(-EINVAL);
+ }
+
+ container = kzalloc(sizeof(*container), GFP_KERNEL);
+ if (!container)
+ return ERR_PTR(-ENOMEM);
+
+ mutex_init(&container->lock);
+
+ return container;
+}
+
+static void tce_iommu_release(void *iommu_data)
+{
+ struct tce_container *container = iommu_data;
+
+ WARN_ON(container->tbl && !container->tbl->it_group);
+ if (container->tbl && container->tbl->it_group)
+ tce_iommu_detach_group(iommu_data, container->tbl->it_group);
+
+ mutex_destroy(&container->lock);
+
+ kfree(container);
+}
+
+static long tce_iommu_ioctl(void *iommu_data,
+ unsigned int cmd, unsigned long arg)
+{
+ struct tce_container *container = iommu_data;
+ unsigned long minsz;
+ long ret;
+
+ switch (cmd) {
+ case VFIO_CHECK_EXTENSION: {
+ return (arg == VFIO_SPAPR_TCE_IOMMU) ? 1 : 0;
+ }
+ case VFIO_IOMMU_SPAPR_TCE_GET_INFO: {
+ struct vfio_iommu_spapr_tce_info info;
+ struct iommu_table *tbl = container->tbl;
+
+ if (WARN_ON(!tbl))
+ return -ENXIO;
+
+ minsz = offsetofend(struct vfio_iommu_spapr_tce_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 = tbl->it_offset << IOMMU_PAGE_SHIFT;
+ info.dma32_window_size = tbl->it_size << IOMMU_PAGE_SHIFT;
+ info.flags = 0;
+
+ if (copy_to_user((void __user *)arg, &info, minsz))
+ return -EFAULT;
+
+ return 0;
+ }
+ case VFIO_IOMMU_MAP_DMA: {
+ vfio_iommu_spapr_tce_dma_map param;
+ struct iommu_table *tbl = container->tbl;
+ enum dma_data_direction direction;
+ unsigned long locked, lock_limit;
+
+ if (WARN_ON(!tbl))
+ return -ENXIO;
+
+ minsz = offsetofend(vfio_iommu_spapr_tce_dma_map, size);
+
+ if (copy_from_user(&param, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (param.argsz < minsz)
+ return -EINVAL;
+
+ if ((param.flags & VFIO_DMA_MAP_FLAG_READ) &&
+ (param.flags & VFIO_DMA_MAP_FLAG_WRITE))
+ direction = DMA_BIDIRECTIONAL;
+ else if (param.flags & VFIO_DMA_MAP_FLAG_READ)
+ direction = DMA_TO_DEVICE;
+ else if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
+ direction = DMA_FROM_DEVICE;
+ else
+ return -EINVAL;
+
+ if ((param.size & ~IOMMU_PAGE_MASK) ||
+ (param.iova & ~IOMMU_PAGE_MASK) ||
+ (param.vaddr & ~IOMMU_PAGE_MASK))
+ return -EINVAL;
+
+ if ((param.iova + param.size) >
+ (tbl->it_size << IOMMU_PAGE_SHIFT))
+ return -EINVAL;
+
+ if (param.iova < (tbl->it_offset << IOMMU_PAGE_SHIFT))
+ return -EINVAL;
+
+ /* Account for locked pages */
+ locked = current->mm->locked_vm +
+ (param.size >> PAGE_SHIFT);
+ lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+ if (locked > lock_limit && !capable(CAP_IPC_LOCK)) {
+ pr_warn("RLIMIT_MEMLOCK (%ld) exceeded\n",
+ rlimit(RLIMIT_MEMLOCK));
+ return -ENOMEM;
+ }
+
+ ret = iommu_put_tces(tbl, param.iova >> IOMMU_PAGE_SHIFT,
+ param.vaddr, direction,
+ param.size >> IOMMU_PAGE_SHIFT);
+
+ if (ret > 0)
+ lock_acct(ret);
+
+ return ret;
+ }
+ case VFIO_IOMMU_UNMAP_DMA: {
+ vfio_iommu_spapr_tce_dma_unmap param;
+ struct iommu_table *tbl = container->tbl;
+
+ if (WARN_ON(!tbl))
+ return -ENXIO;
+
+ minsz = offsetofend(vfio_iommu_spapr_tce_dma_unmap, size);
+
+ if (copy_from_user(&param, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (param.argsz < minsz)
+ return -EINVAL;
+
+ if ((param.size & ~IOMMU_PAGE_MASK) ||
+ (param.iova & ~IOMMU_PAGE_MASK))
+ return -EINVAL;
+
+ if ((param.iova + param.size) >
+ (tbl->it_size << IOMMU_PAGE_SHIFT))
+ return -EINVAL;
+
+ if (param.iova < (tbl->it_offset << IOMMU_PAGE_SHIFT))
+ return -EINVAL;
+
+ ret = iommu_clear_tces(tbl, param.iova >> IOMMU_PAGE_SHIFT,
+ param.size >> IOMMU_PAGE_SHIFT);
+
+ if (ret > 0)
+ lock_acct(-ret);
+
+ return ret;
+ }
+ default:
+ pr_warn("tce_vfio: unexpected cmd %x\n", cmd);
+ }
+
+ return -ENOTTY;
+}
+
+static int tce_iommu_attach_group(void *iommu_data,
+ struct iommu_group *iommu_group)
+{
+ struct tce_container *container = iommu_data;
+ struct iommu_table *tbl = iommu_group_get_iommudata(iommu_group);
+
+ BUG_ON(!tbl);
+ mutex_lock(&container->lock);
+ pr_debug("tce_vfio: Attaching group #%u to iommu %p\n",
+ iommu_group_id(iommu_group), iommu_group);
+ if (container->tbl) {
+ pr_warn("tce_vfio: Only one group per IOMMU container is allowed, existing id=%d, attaching id=%d\n",
+ iommu_group_id(container->tbl->it_group),
+ iommu_group_id(iommu_group));
+ mutex_unlock(&container->lock);
+ return -EBUSY;
+ }
+
+ container->tbl = tbl;
+ iommu_clear_tces(tbl, tbl->it_offset, tbl->it_size);
+ mutex_unlock(&container->lock);
+
+ return 0;
+}
+
+static void tce_iommu_detach_group(void *iommu_data,
+ struct iommu_group *iommu_group)
+{
+ struct tce_container *container = iommu_data;
+ struct iommu_table *tbl = iommu_group_get_iommudata(iommu_group);
+
+ BUG_ON(!tbl);
+ mutex_lock(&container->lock);
+ if (tbl != container->tbl) {
+ pr_warn("tce_vfio: detaching group #%u, expected group is #%u\n",
+ iommu_group_id(iommu_group),
+ iommu_group_id(tbl->it_group));
+ } else {
+
+ pr_debug("tce_vfio: detaching group #%u from iommu %p\n",
+ iommu_group_id(iommu_group), iommu_group);
+
+ iommu_clear_tces(tbl, tbl->it_offset, tbl->it_size);
+ container->tbl = NULL;
+ /* Restore reserve for page 0 */
+ if (tbl->it_offset == 0)
+ set_bit(0, tbl->it_map);
+
+ }
+ mutex_unlock(&container->lock);
+}
+
+const struct vfio_iommu_driver_ops tce_iommu_driver_ops = {
+ .name = "iommu-vfio-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)
+{
+ 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);
+
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 0a4f180..a12295c 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -99,6 +99,7 @@ extern void vfio_unregister_iommu_driver(
/* Extensions */

#define VFIO_TYPE1_IOMMU 1
+#define VFIO_SPAPR_TCE_IOMMU 2

/*
* The IOCTL interface is designed for extensibility by embedding the
@@ -442,4 +443,29 @@ struct vfio_iommu_type1_dma_unmap {

#define VFIO_IOMMU_UNMAP_DMA _IO(VFIO_TYPE, VFIO_BASE + 14)

+/* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
+
+/*
+ * The SPAPR TCE info struct provides the information about the PCI bus
+ * address ranges available for DMA, these values are programmed into
+ * the hardware so the guest has to know that information.
+ *
+ * The IOMMU page size is always 4K.
+ */
+
+struct vfio_iommu_spapr_tce_info {
+ __u32 argsz;
+ __u32 flags; /* reserved for future use */
+ __u32 dma32_window_start; /* 32 bit window start (bytes) */
+ __u32 dma32_window_size; /* 32 bit window size (bytes) */
+};
+
+#define VFIO_IOMMU_SPAPR_TCE_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12)
+
+/* Reuse type1 map/unmap structs as they are the same at the moment */
+typedef struct vfio_iommu_type1_dma_map vfio_iommu_spapr_tce_dma_map;
+typedef struct vfio_iommu_type1_dma_unmap vfio_iommu_spapr_tce_dma_unmap;
+
+/* ***************************************************************** */
+
#endif /* VFIO_H */
--
1.7.10.4


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