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SubjectRe: [PATCH]intel-iommu batched iotlb flushes
On Mon, Feb 11, 2008 at 03:27:16PM -0800, Randy Dunlap wrote:
> On Mon, 11 Feb 2008 14:41:05 -0800 mark gross wrote:
>
> > The hole is the following scenarios:
> > do many map_signal operations, do some unmap_signals, reuse a recently
> > unmapped page, <errant DMA hardware sneaks through and steps on reused
> > memory>
> >
> > Or: you have rouge hardware using DMA's to look at pages: do many
>
> or rogue hardware?

yes bad-guy hardware.

>
> > map_signal's, do many unmap_singles, reuse some unmapped pages :
>
> signal .................... single
>
> > <rouge hardware looks at reused page>
>
> why rouge?

because I'm a dumb ass.

>
> > Note : these holes are very hard to get too, as the IOTLB is small and
> > only the PTE's still in the IOTLB can be accessed through this
> > mechanism.
> >
> > Its recommended that strict is used when developing drivers that do DMA
> > operations to catch bugs early. For production code where performance
> > is desired running with the batched IOTLB flushing is a good way to
> > go.
> >
> >
> > --mgross
> >
> >
> > Signed-off-by: <mgross@linux.intel.com>
> >
> >
> >
> > Index: linux-2.6.24-mm1/drivers/pci/intel-iommu.c
> > ===================================================================
> > --- linux-2.6.24-mm1.orig/drivers/pci/intel-iommu.c 2008-02-07 13:03:10.000000000 -0800
> > +++ linux-2.6.24-mm1/drivers/pci/intel-iommu.c 2008-02-11 10:38:49.000000000 -0800
>
> > @@ -50,11 +52,39 @@
> >
> > #define DOMAIN_MAX_ADDR(gaw) ((((u64)1) << gaw) - 1)
> >
> > +
> > +static void flush_unmaps_timeout(unsigned long data);
> > +
> > +static struct timer_list unmap_timer =
> > + TIMER_INITIALIZER(flush_unmaps_timeout, 0, 0);
> > +
> > +struct unmap_list {
> > + struct list_head list;
> > + struct dmar_domain *domain;
> > + struct iova *iova;
> > +};
> > +
> > +static struct intel_iommu *g_iommus;
> > +/* bitmap for indexing intel_iommus */
> > +static unsigned long *g_iommus_to_flush;
> > +static int g_num_of_iommus;
> > +
> > +static DEFINE_SPINLOCK(async_umap_flush_lock);
> > +static LIST_HEAD(unmaps_to_do);
> > +
> > +static int timer_on;
> > +static long list_size;
> > +static int high_watermark;
> > +
> > +static struct dentry *intel_iommu_debug, *debug;
> > +
> > +
> > static void domain_remove_dev_info(struct dmar_domain *domain);
> >
> > static int dmar_disabled;
> > static int __initdata dmar_map_gfx = 1;
> > static int dmar_forcedac;
> > +static int intel_iommu_strict;
> >
> > #define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1))
> > static DEFINE_SPINLOCK(device_domain_lock);
> > @@ -73,9 +103,13 @@
> > printk(KERN_INFO
> > "Intel-IOMMU: disable GFX device mapping\n");
> > } else if (!strncmp(str, "forcedac", 8)) {
> > - printk (KERN_INFO
> > + printk(KERN_INFO
> > "Intel-IOMMU: Forcing DAC for PCI devices\n");
> > dmar_forcedac = 1;
> > + } else if (!strncmp(str, "strict", 8)) {
> > + printk(KERN_INFO
> > + "Intel-IOMMU: disable bached IOTLB flush\n");
>
> batched

fixed.

>
> > + intel_iommu_strict = 1;
> > }
> >
> > str += strcspn(str, ",");
>
> > @@ -1672,7 +1702,29 @@
> > for_each_drhd_unit(drhd) {
> > if (drhd->ignored)
> > continue;
> > - iommu = alloc_iommu(drhd);
> > + g_num_of_iommus++;
> > + }
> > +
> > + nlongs = BITS_TO_LONGS(g_num_of_iommus);
> > + g_iommus_to_flush = kzalloc(nlongs * sizeof(unsigned long), GFP_KERNEL);
> > + if (!g_iommus_to_flush) {
> > + printk(KERN_ERR "Allocating bitmap array failed\n");
>
> identify: "IOMMU:
>
> > + return -ENOMEM;
> > + }
> > +
> > + g_iommus = kzalloc(g_num_of_iommus * sizeof(*iommu), GFP_KERNEL);
> > + if (!g_iommus) {
> > + kfree(g_iommus_to_flush);
> > + ret = -ENOMEM;
> > + goto error;
> > + }
> > +
> > + i = 0;
> > + for_each_drhd_unit(drhd) {
> > + if (drhd->ignored)
> > + continue;
> > + iommu = alloc_iommu(&g_iommus[i], drhd);
> > + i++;
> > if (!iommu) {
> > ret = -ENOMEM;
> > goto error;
>
> > Index: linux-2.6.24-mm1/Documentation/kernel-parameters.txt
> > ===================================================================
> > --- linux-2.6.24-mm1.orig/Documentation/kernel-parameters.txt 2008-02-11 13:44:23.000000000 -0800
> > +++ linux-2.6.24-mm1/Documentation/kernel-parameters.txt 2008-02-11 14:23:37.000000000 -0800
> > @@ -822,6 +822,10 @@
> > than 32 bit addressing. The default is to look
> > for translation below 32 bit and if not available
> > then look in the higher range.
> > + strict [Default Off]
> > + With this option on every umap_signle will
>
> on, every unmap_si{ngle,gnal} ??
>

fixed.


> > + result in a hardware IOTLB flush opperation as
> > + opposed to batching them for performance.
> >
> > io_delay= [X86-32,X86-64] I/O delay method
> > 0x80
>
>

thanks!

Signed-off-by: <mgross@linux.intel.com>


Index: linux-2.6.24-mm1/drivers/pci/intel-iommu.c
===================================================================
--- linux-2.6.24-mm1.orig/drivers/pci/intel-iommu.c 2008-02-12 07:12:06.000000000 -0800
+++ linux-2.6.24-mm1/drivers/pci/intel-iommu.c 2008-02-12 07:47:04.000000000 -0800
@@ -21,6 +21,7 @@

#include <linux/init.h>
#include <linux/bitmap.h>
+#include <linux/debugfs.h>
#include <linux/slab.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
@@ -30,6 +31,7 @@
#include <linux/dmar.h>
#include <linux/dma-mapping.h>
#include <linux/mempool.h>
+#include <linux/timer.h>
#include "iova.h"
#include "intel-iommu.h"
#include <asm/proto.h> /* force_iommu in this header in x86-64*/
@@ -50,11 +52,39 @@

#define DOMAIN_MAX_ADDR(gaw) ((((u64)1) << gaw) - 1)

+
+static void flush_unmaps_timeout(unsigned long data);
+
+static struct timer_list unmap_timer =
+ TIMER_INITIALIZER(flush_unmaps_timeout, 0, 0);
+
+struct unmap_list {
+ struct list_head list;
+ struct dmar_domain *domain;
+ struct iova *iova;
+};
+
+static struct intel_iommu *g_iommus;
+/* bitmap for indexing intel_iommus */
+static unsigned long *g_iommus_to_flush;
+static int g_num_of_iommus;
+
+static DEFINE_SPINLOCK(async_umap_flush_lock);
+static LIST_HEAD(unmaps_to_do);
+
+static int timer_on;
+static long list_size;
+static int high_watermark;
+
+static struct dentry *intel_iommu_debug, *debug;
+
+
static void domain_remove_dev_info(struct dmar_domain *domain);

static int dmar_disabled;
static int __initdata dmar_map_gfx = 1;
static int dmar_forcedac;
+static int intel_iommu_strict;

#define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1))
static DEFINE_SPINLOCK(device_domain_lock);
@@ -73,9 +103,13 @@
printk(KERN_INFO
"Intel-IOMMU: disable GFX device mapping\n");
} else if (!strncmp(str, "forcedac", 8)) {
- printk (KERN_INFO
+ printk(KERN_INFO
"Intel-IOMMU: Forcing DAC for PCI devices\n");
dmar_forcedac = 1;
+ } else if (!strncmp(str, "strict", 8)) {
+ printk(KERN_INFO
+ "Intel-IOMMU: disable batched IOTLB flush\n");
+ intel_iommu_strict = 1;
}

str += strcspn(str, ",");
@@ -965,17 +999,13 @@
set_bit(0, iommu->domain_ids);
return 0;
}
-
-static struct intel_iommu *alloc_iommu(struct dmar_drhd_unit *drhd)
+static struct intel_iommu *alloc_iommu(struct intel_iommu *iommu,
+ struct dmar_drhd_unit *drhd)
{
- struct intel_iommu *iommu;
int ret;
int map_size;
u32 ver;

- iommu = kzalloc(sizeof(*iommu), GFP_KERNEL);
- if (!iommu)
- return NULL;
iommu->reg = ioremap(drhd->reg_base_addr, PAGE_SIZE_4K);
if (!iommu->reg) {
printk(KERN_ERR "IOMMU: can't map the region\n");
@@ -1396,7 +1426,7 @@
int index;

while (dev) {
- for (index = 0; index < cnt; index ++)
+ for (index = 0; index < cnt; index++)
if (dev == devices[index])
return 1;

@@ -1661,7 +1691,7 @@
struct dmar_rmrr_unit *rmrr;
struct pci_dev *pdev;
struct intel_iommu *iommu;
- int ret, unit = 0;
+ int nlongs, i, ret, unit = 0;

/*
* for each drhd
@@ -1672,7 +1702,30 @@
for_each_drhd_unit(drhd) {
if (drhd->ignored)
continue;
- iommu = alloc_iommu(drhd);
+ g_num_of_iommus++;
+ }
+
+ nlongs = BITS_TO_LONGS(g_num_of_iommus);
+ g_iommus_to_flush = kzalloc(nlongs * sizeof(unsigned long), GFP_KERNEL);
+ if (!g_iommus_to_flush) {
+ printk(KERN_ERR "Intel-IOMMU: \
+ Allocating bitmap array failed\n");
+ return -ENOMEM;
+ }
+
+ g_iommus = kzalloc(g_num_of_iommus * sizeof(*iommu), GFP_KERNEL);
+ if (!g_iommus) {
+ kfree(g_iommus_to_flush);
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ i = 0;
+ for_each_drhd_unit(drhd) {
+ if (drhd->ignored)
+ continue;
+ iommu = alloc_iommu(&g_iommus[i], drhd);
+ i++;
if (!iommu) {
ret = -ENOMEM;
goto error;
@@ -1705,7 +1758,6 @@
* endfor
*/
for_each_rmrr_units(rmrr) {
- int i;
for (i = 0; i < rmrr->devices_cnt; i++) {
pdev = rmrr->devices[i];
/* some BIOS lists non-exist devices in DMAR table */
@@ -1909,6 +1961,54 @@
return 0;
}

+static void flush_unmaps(void)
+{
+ struct iova *node, *n;
+ unsigned long flags;
+ int i;
+
+ spin_lock_irqsave(&async_umap_flush_lock, flags);
+ timer_on = 0;
+
+ /*just flush them all*/
+ for (i = 0; i < g_num_of_iommus; i++) {
+ if (test_and_clear_bit(i, g_iommus_to_flush))
+ iommu_flush_iotlb_global(&g_iommus[i], 0);
+ }
+
+ list_for_each_entry_safe(node, n, &unmaps_to_do, list) {
+ /* free iova */
+ list_del(&node->list);
+ __free_iova(&((struct dmar_domain *)node->dmar)->iovad, node);
+
+ }
+ list_size = 0;
+ spin_unlock_irqrestore(&async_umap_flush_lock, flags);
+}
+
+static void flush_unmaps_timeout(unsigned long data)
+{
+ flush_unmaps();
+}
+
+static void add_unmap(struct dmar_domain *dom, struct iova *iova)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&async_umap_flush_lock, flags);
+ iova->dmar = dom;
+ list_add(&iova->list, &unmaps_to_do);
+ set_bit((dom->iommu - g_iommus), g_iommus_to_flush);
+
+ if (!timer_on) {
+ unmap_timer.expires = jiffies + msecs_to_jiffies(10);
+ mod_timer(&unmap_timer, unmap_timer.expires);
+ timer_on = 1;
+ }
+ list_size++;
+ spin_unlock_irqrestore(&async_umap_flush_lock, flags);
+}
+
static void intel_unmap_single(struct device *dev, dma_addr_t dev_addr,
size_t size, int dir)
{
@@ -1936,13 +2036,21 @@
dma_pte_clear_range(domain, start_addr, start_addr + size);
/* free page tables */
dma_pte_free_pagetable(domain, start_addr, start_addr + size);
-
- if (iommu_flush_iotlb_psi(domain->iommu, domain->id, start_addr,
- size >> PAGE_SHIFT_4K, 0))
- iommu_flush_write_buffer(domain->iommu);
-
- /* free iova */
- __free_iova(&domain->iovad, iova);
+ if (intel_iommu_strict) {
+ if (iommu_flush_iotlb_psi(domain->iommu,
+ domain->id, start_addr, size >> PAGE_SHIFT_4K, 0))
+ iommu_flush_write_buffer(domain->iommu);
+ /* free iova */
+ __free_iova(&domain->iovad, iova);
+ } else {
+ add_unmap(domain, iova);
+ /*
+ * queue up the release of the unmap to save the 1/6th of the
+ * cpu used up by the iotlb flush operation...
+ */
+ if (list_size > high_watermark)
+ flush_unmaps();
+ }
}

static void * intel_alloc_coherent(struct device *hwdev, size_t size,
@@ -2266,6 +2374,10 @@
if (dmar_table_init())
return -ENODEV;

+ high_watermark = 250;
+ intel_iommu_debug = debugfs_create_dir("intel_iommu", NULL);
+ debug = debugfs_create_u32("high_watermark", S_IWUGO | S_IRUGO,
+ intel_iommu_debug, &high_watermark);
iommu_init_mempool();
dmar_init_reserved_ranges();

@@ -2281,6 +2393,7 @@
printk(KERN_INFO
"PCI-DMA: Intel(R) Virtualization Technology for Directed I/O\n");

+ init_timer(&unmap_timer);
force_iommu = 1;
dma_ops = &intel_dma_ops;
return 0;
Index: linux-2.6.24-mm1/drivers/pci/iova.h
===================================================================
--- linux-2.6.24-mm1.orig/drivers/pci/iova.h 2008-02-12 07:12:06.000000000 -0800
+++ linux-2.6.24-mm1/drivers/pci/iova.h 2008-02-12 07:39:53.000000000 -0800
@@ -23,6 +23,8 @@
struct rb_node node;
unsigned long pfn_hi; /* IOMMU dish out addr hi */
unsigned long pfn_lo; /* IOMMU dish out addr lo */
+ struct list_head list;
+ void *dmar;
};

/* holds all the iova translations for a domain */
Index: linux-2.6.24-mm1/Documentation/kernel-parameters.txt
===================================================================
--- linux-2.6.24-mm1.orig/Documentation/kernel-parameters.txt 2008-02-12 07:12:06.000000000 -0800
+++ linux-2.6.24-mm1/Documentation/kernel-parameters.txt 2008-02-12 07:47:02.000000000 -0800
@@ -822,6 +822,10 @@
than 32 bit addressing. The default is to look
for translation below 32 bit and if not available
then look in the higher range.
+ strict [Default Off]
+ With this option on every umap_signal opperation will
+ result in a hardware IOTLB flush opperation as opposed
+ to batching them for performance.

io_delay= [X86-32,X86-64] I/O delay method
0x80

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