On 27/11/12 15:29, Alex Williamson wrote:
On Tue, 2012-11-27 at 15:06 +1100, Alexey Kardashevskiy wrote:
On 27/11/12 05:20, Alex Williamson wrote:
On Fri, 2012-11-23 at 20:03 +1100, Alexey Kardashevskiy wrote:
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@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
---
drivers/vfio/Kconfig | 6 +
drivers/vfio/Makefile | 1 +
drivers/vfio/vfio_iommu_spapr_tce.c | 247 +++++++++++++++++++++++++++++++++++
include/linux/vfio.h | 20 +++
4 files changed, 274 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..46a6298
--- /dev/null
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -0,0 +1,247 @@
+/*
+ * 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_type1.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/err.h>
+#include <linux/vfio.h>
+#include <asm/iommu.h>
+
+#define DRIVER_VERSION "0.1"
+#define DRIVER_AUTHOR "aik@xxxxxxxxx"
+#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
+ */
+
+/*
+ * 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) {
+ printk(KERN_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);
I think your patch ordering is backwards here. it_group isn't added
until 2/2. I'd really like to see the arch/powerpc code approved and
merged by the powerpc maintainer before we add the code that makes use
of it into vfio. Otherwise we just get lots of churn if interfaces
change or they disapprove of it altogether.
Makes sense, thanks.
+ 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;
+
+ 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,
+ dma64_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.dma64_window_start = 0;
+ info.dma64_window_size = 0;
+ 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 = DMA_NONE;
+
+ if (WARN_ON(!tbl))
+ return -ENXIO;
+
+ minsz = offsetofend(vfio_iommu_spapr_tce_dma_map, size);
+
+ if (copy_from_user(¶m, (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;
+ }
+
+ param.size += param.iova & ~IOMMU_PAGE_MASK;
+ param.size = _ALIGN_UP(param.size, IOMMU_PAGE_SIZE);
On x86 we force iova, vaddr, and size to all be aligned to the smallest
page granularity of the iommu and return -EINVAL if it doesn't fit.
What does it imply to the user if they're always aligned to work here?
Won't this interface happily map overlapping entries with no indication
to the user that the previous mapping is no longer valid?
Maybe another reason why a combined unmap/map makes me nervous, we have
to assume the user knows what they're doing.
I got used to guests which do know what they are doing so I am pretty calm :)
but ok, I'll move alignment to the QEMU, it makes sense.
+
+ return iommu_put_tces(tbl, param.iova >> IOMMU_PAGE_SHIFT,
+ param.vaddr & IOMMU_PAGE_MASK, direction,
+ param.size >> IOMMU_PAGE_SHIFT);
+ }
+ 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(¶m, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ if (param.argsz < minsz)
+ return -EINVAL;
+
+ param.size += param.iova & ~IOMMU_PAGE_MASK;
+ param.size = _ALIGN_UP(param.size, IOMMU_PAGE_SIZE);
+
+ return iommu_put_tces(tbl, param.iova >> IOMMU_PAGE_SHIFT,
+ 0, DMA_NONE, param.size >> IOMMU_PAGE_SHIFT);
+ }
+ default:
+ printk(KERN_WARNING "tce_vfio: unexpected cmd %x\n", cmd);
pr_warn
+ }
+
+ 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) {
+ printk(KERN_WARNING "tce_vfio: Only one group per IOMMU container is allowed, existing id=%d, attaching id=%d\n",
pr_warn
+ iommu_group_id(container->tbl->it_group),
+ iommu_group_id(iommu_group));
+ mutex_unlock(&container->lock);
+ return -EBUSY;
+ }
+
+ container->tbl = tbl;
Would it be too much paranoia to clear all the tce here as you do below
on detach?
Guess so. I do unmap on detach() and the guest calls put_tce(0) (i.e.
unmaps) the whole DMA window at the boot time.
But that's just one user of this interface, we can't assume they'll all
be so agreeable. If any tces were enabled here, a malicious user would
have a window to host memory, right? Thanks,
But I still release pages on detach(), how can this code be not called on
the guest exit (normal or crashed)?
Alex
--
Alexey
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