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authorAlexey Kardashevskiy <aik@ozlabs.ru>2013-05-21 13:33:10 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-06-20 16:55:14 +1000
commit5ffd229c02731a91d08ca21e76b503c5bbb5c095 (patch)
treeed5f684cb6a5b683846d6b3d97fa2c0999835c24 /drivers/vfio/vfio_iommu_spapr_tce.c
parent4e13c1ac6baa1d6c2b650d66ca89e1e12727ec19 (diff)
powerpc/vfio: Implement IOMMU driver for VFIO
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 implements an IOMMU driver for VFIO which does mapping/unmapping pages for the guest IO and provides information about DMA window (required by a POWER guest). Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Paul Mackerras <paulus@samba.org> Acked-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'drivers/vfio/vfio_iommu_spapr_tce.c')
-rw-r--r--drivers/vfio/vfio_iommu_spapr_tce.c377
1 files changed, 377 insertions, 0 deletions
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
new file mode 100644
index 000000000000..bdae7a04af75
--- /dev/null
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -0,0 +1,377 @@
+/*
+ * VFIO: IOMMU DMA mapping support for TCE on POWER
+ *
+ * Copyright (C) 2013 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>
+#include <asm/tce.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
+ */
+
+/*
+ * 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;
+ bool enabled;
+};
+
+static int tce_iommu_enable(struct tce_container *container)
+{
+ int ret = 0;
+ unsigned long locked, lock_limit, npages;
+ struct iommu_table *tbl = container->tbl;
+
+ if (!container->tbl)
+ return -ENXIO;
+
+ if (!current->mm)
+ return -ESRCH; /* process exited */
+
+ if (container->enabled)
+ return -EBUSY;
+
+ /*
+ * When userspace pages are mapped into the IOMMU, they are effectively
+ * locked memory, so, theoretically, we need to update the accounting
+ * of locked pages on each map and unmap. For powerpc, the map unmap
+ * paths can be very hot, though, and the accounting would kill
+ * performance, especially since it would be difficult to impossible
+ * to handle the accounting in real mode only.
+ *
+ * To address that, rather than precisely accounting every page, we
+ * instead account for a worst case on locked memory when the iommu is
+ * enabled and disabled. The worst case upper bound on locked memory
+ * is the size of the whole iommu window, which is usually relatively
+ * small (compared to total memory sizes) on POWER hardware.
+ *
+ * Also we don't have a nice way to fail on H_PUT_TCE due to ulimits,
+ * that would effectively kill the guest at random points, much better
+ * enforcing the limit based on the max that the guest can map.
+ */
+ down_write(&current->mm->mmap_sem);
+ npages = (tbl->it_size << IOMMU_PAGE_SHIFT) >> PAGE_SHIFT;
+ locked = current->mm->locked_vm + npages;
+ 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));
+ ret = -ENOMEM;
+ } else {
+
+ current->mm->locked_vm += npages;
+ container->enabled = true;
+ }
+ up_write(&current->mm->mmap_sem);
+
+ return ret;
+}
+
+static void tce_iommu_disable(struct tce_container *container)
+{
+ if (!container->enabled)
+ return;
+
+ container->enabled = false;
+
+ if (!container->tbl || !current->mm)
+ return;
+
+ down_write(&current->mm->mmap_sem);
+ current->mm->locked_vm -= (container->tbl->it_size <<
+ IOMMU_PAGE_SHIFT) >> PAGE_SHIFT;
+ up_write(&current->mm->mmap_sem);
+}
+
+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);
+ tce_iommu_disable(container);
+
+ 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: {
+ struct vfio_iommu_type1_dma_map param;
+ struct iommu_table *tbl = container->tbl;
+ unsigned long tce, i;
+
+ if (!tbl)
+ return -ENXIO;
+
+ BUG_ON(!tbl->it_group);
+
+ minsz = offsetofend(struct vfio_iommu_type1_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 |
+ VFIO_DMA_MAP_FLAG_WRITE))
+ return -EINVAL;
+
+ if ((param.size & ~IOMMU_PAGE_MASK) ||
+ (param.vaddr & ~IOMMU_PAGE_MASK))
+ return -EINVAL;
+
+ /* iova is checked by the IOMMU API */
+ tce = param.vaddr;
+ if (param.flags & VFIO_DMA_MAP_FLAG_READ)
+ tce |= TCE_PCI_READ;
+ if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
+ tce |= TCE_PCI_WRITE;
+
+ ret = iommu_tce_put_param_check(tbl, param.iova, tce);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < (param.size >> IOMMU_PAGE_SHIFT); ++i) {
+ ret = iommu_put_tce_user_mode(tbl,
+ (param.iova >> IOMMU_PAGE_SHIFT) + i,
+ tce);
+ if (ret)
+ break;
+ tce += IOMMU_PAGE_SIZE;
+ }
+ if (ret)
+ iommu_clear_tces_and_put_pages(tbl,
+ param.iova >> IOMMU_PAGE_SHIFT, i);
+
+ iommu_flush_tce(tbl);
+
+ return ret;
+ }
+ case VFIO_IOMMU_UNMAP_DMA: {
+ struct vfio_iommu_type1_dma_unmap param;
+ struct iommu_table *tbl = container->tbl;
+
+ if (WARN_ON(!tbl))
+ return -ENXIO;
+
+ minsz = offsetofend(struct vfio_iommu_type1_dma_unmap,
+ size);
+
+ if (copy_from_user(&param, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (param.argsz < minsz)
+ return -EINVAL;
+
+ /* No flag is supported now */
+ if (param.flags)
+ return -EINVAL;
+
+ if (param.size & ~IOMMU_PAGE_MASK)
+ return -EINVAL;
+
+ ret = iommu_tce_clear_param_check(tbl, param.iova, 0,
+ param.size >> IOMMU_PAGE_SHIFT);
+ if (ret)
+ return ret;
+
+ ret = iommu_clear_tces_and_put_pages(tbl,
+ param.iova >> IOMMU_PAGE_SHIFT,
+ param.size >> IOMMU_PAGE_SHIFT);
+ iommu_flush_tce(tbl);
+
+ return ret;
+ }
+ case VFIO_IOMMU_ENABLE:
+ mutex_lock(&container->lock);
+ ret = tce_iommu_enable(container);
+ mutex_unlock(&container->lock);
+ return ret;
+
+
+ case VFIO_IOMMU_DISABLE:
+ mutex_lock(&container->lock);
+ tce_iommu_disable(container);
+ mutex_unlock(&container->lock);
+ return 0;
+ }
+
+ return -ENOTTY;
+}
+
+static int tce_iommu_attach_group(void *iommu_data,
+ struct iommu_group *iommu_group)
+{
+ int ret;
+ 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));
+ ret = -EBUSY;
+ } else if (container->enabled) {
+ pr_err("tce_vfio: attaching group #%u to enabled container\n",
+ iommu_group_id(iommu_group));
+ ret = -EBUSY;
+ } else {
+ ret = iommu_take_ownership(tbl);
+ if (!ret)
+ container->tbl = tbl;
+ }
+
+ mutex_unlock(&container->lock);
+
+ return ret;
+}
+
+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 {
+ if (container->enabled) {
+ pr_warn("tce_vfio: detaching group #%u from enabled container, forcing disable\n",
+ iommu_group_id(tbl->it_group));
+ tce_iommu_disable(container);
+ }
+
+ /* pr_debug("tce_vfio: detaching group #%u from iommu %p\n",
+ iommu_group_id(iommu_group), iommu_group); */
+ container->tbl = NULL;
+ iommu_release_ownership(tbl);
+ }
+ 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);
+