[RFC 7/7] iommu/core: split mapping to page sizes as supported by the hardware
Ohad Ben-Cohen
ohad at wizery.com
Fri Sep 2 13:32:36 EDT 2011
When mapping a memory region, split it to page sizes as supported
by the iommu hardware. Always prefer bigger pages, when possible,
in order to reduce the TLB pressure.
Conversely, when unmapping a memory region, iterate through its pages,
until the region is completely unmapped.
The logic to do that is now added to the IOMMU core, so neither the iommu
drivers themselves nor users of the IOMMU API have to duplicate it.
This is needed by future users (generic DMA-API, remoteproc and tidspbridge
to name a few) and could potentially also simplify existing users
(amd_iommu's iommu_unmap_page, intel-iommu's hardware_largepage_caps, and
possibly kvm_iommu_put_pages too).
This allows a more lenient granularity of mappings: traditionally the
IOMMU API took 'order' (of a page) as a mapping size, and directly let
the low level iommu drivers handle the mapping. Now that the IOMMU
core can split arbitrary memory regions into pages, we can remove this
limitation, so users don't have to split those regions by themselves.
Currently the supported page sizes are advertised once and they then
remain static. That works well for OMAP (and seemingly MSM too) but
it would probably not fly with intel's hardware, where the page size
capabilities seem to have the potential to be different between
several DMA remapping devices (so we might have to maintain this pgsize
bitmap information per IOMMU device).
Mainline users of the IOMMU API (kvm and omap-iovmm) are adopted
appropriately. Only OMAP and MSM were changed to advertise the supported
page sizes at this point (so this is definitely not merging material).
Signed-off-by: Ohad Ben-Cohen <ohad at wizery.com>
---
drivers/iommu/iommu.c | 127 +++++++++++++++++++++++++++++++++++++++----
drivers/iommu/msm_iommu.c | 8 +++-
drivers/iommu/omap-iommu.c | 6 ++-
drivers/iommu/omap-iovmm.c | 12 +---
include/linux/iommu.h | 7 ++-
virt/kvm/iommu.c | 4 +-
6 files changed, 136 insertions(+), 28 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index c08f1a0..b5c6d63 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -16,6 +16,8 @@
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
#include <linux/kernel.h>
#include <linux/bug.h>
#include <linux/types.h>
@@ -23,15 +25,41 @@
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/iommu.h>
+#include <linux/bitmap.h>
static struct iommu_ops *iommu_ops;
-void register_iommu(struct iommu_ops *ops)
+/* bitmap of supported page sizes */
+static unsigned long *iommu_pgsize_bitmap;
+
+/* number of bits used to represent the supported pages */
+static unsigned int iommu_nr_page_bits;
+
+/* size of the smallest supported page (in bytes) */
+static unsigned int iommu_min_pagesz;
+
+/* bit number of the smallest supported page */
+static unsigned int iommu_min_page_idx;
+
+/**
+ * register_iommu() - register an IOMMU hardware
+ * @ops: iommu handlers
+ * @pgsize_bitmap: bitmap of page sizes supported by the hardware
+ * @nr_page_bits: size of @pgsize_bitmap (in bits)
+ */
+void register_iommu(struct iommu_ops *ops, unsigned long *pgsize_bitmap,
+ unsigned int nr_page_bits)
{
- if (iommu_ops)
+ if (iommu_ops || iommu_pgsize_bitmap || !nr_page_bits)
BUG();
iommu_ops = ops;
+ iommu_pgsize_bitmap = pgsize_bitmap;
+ iommu_nr_page_bits = nr_page_bits;
+
+ /* find the minimum page size and its index only once */
+ iommu_min_page_idx = find_first_bit(pgsize_bitmap, nr_page_bits);
+ iommu_min_pagesz = 1 << iommu_min_page_idx;
}
bool iommu_found(void)
@@ -104,26 +132,101 @@ int iommu_domain_has_cap(struct iommu_domain *domain,
EXPORT_SYMBOL_GPL(iommu_domain_has_cap);
int iommu_map(struct iommu_domain *domain, unsigned long iova,
- phys_addr_t paddr, int gfp_order, int prot)
+ phys_addr_t paddr, size_t size, int prot)
{
- size_t size;
+ int ret = 0;
+
+ /*
+ * both the virtual address and the physical one, as well as
+ * the size of the mapping, must be aligned (at least) to the
+ * size of the smallest page supported by the hardware
+ */
+ if (!IS_ALIGNED(iova | paddr | size, iommu_min_pagesz)) {
+ pr_err("unaligned: iova 0x%lx pa 0x%x size 0x%x min_pagesz "
+ "0x%x\n", iova, paddr, size, iommu_min_pagesz);
+ return -EINVAL;
+ }
+
+ pr_debug("map this: iova 0x%lx pa 0x%x size 0x%x\n", iova, paddr, size);
+
+ while (size) {
+ unsigned long pgsize = iommu_min_pagesz;
+ unsigned long idx = iommu_min_page_idx;
+ unsigned long addr_merge = iova | paddr;
+ int order;
+
+ /* find the max page size with which iova, paddr are aligned */
+ for (;;) {
+ unsigned long try_pgsize;
- size = 0x1000UL << gfp_order;
+ idx = find_next_bit(iommu_pgsize_bitmap,
+ iommu_nr_page_bits, idx + 1);
- BUG_ON(!IS_ALIGNED(iova | paddr, size));
+ /* no more pages to check ? */
+ if (idx >= iommu_nr_page_bits)
+ break;
- return iommu_ops->map(domain, iova, paddr, gfp_order, prot);
+ try_pgsize = 1 << idx;
+
+ /* page too big ? addresses not aligned ? */
+ if (size < try_pgsize ||
+ !IS_ALIGNED(addr_merge, try_pgsize))
+ break;
+
+ pgsize = try_pgsize;
+ }
+
+ order = get_order(pgsize);
+
+ pr_debug("mapping: iova 0x%lx pa 0x%x order %d\n", iova,
+ paddr, order);
+
+ ret = iommu_ops->map(domain, iova, paddr, order, prot);
+ if (ret)
+ break;
+
+ size -= pgsize;
+ iova += pgsize;
+ paddr += pgsize;
+ }
+
+ return ret;
}
EXPORT_SYMBOL_GPL(iommu_map);
-int iommu_unmap(struct iommu_domain *domain, unsigned long iova, int gfp_order)
+int iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
{
- size_t size;
+ int order, unmapped_size, unmapped_order, total_unmapped = 0;
+
+ /*
+ * The virtual address, as well as the size of the mapping, must be
+ * aligned (at least) to the size of the smallest page supported
+ * by the hardware
+ */
+ if (!IS_ALIGNED(iova | size, iommu_min_pagesz)) {
+ pr_err("unaligned: iova 0x%lx size 0x%x min_pagesz 0x%x\n",
+ iova, size, iommu_min_pagesz);
+ return -EINVAL;
+ }
+
+ pr_debug("unmap this: iova 0x%lx size 0x%x\n", iova, size);
+
+ while (size > total_unmapped) {
+ order = get_order(size - total_unmapped);
+
+ unmapped_order = iommu_ops->unmap(domain, iova, order);
+ if (unmapped_order < 0)
+ return unmapped_order;
+
+ pr_debug("unmapped: iova 0x%lx order %d\n", iova,
+ unmapped_order);
- size = 0x1000UL << gfp_order;
+ unmapped_size = 0x1000UL << unmapped_order;
- BUG_ON(!IS_ALIGNED(iova, size));
+ iova += unmapped_size;
+ total_unmapped += unmapped_size;
+ }
- return iommu_ops->unmap(domain, iova, gfp_order);
+ return get_order(total_unmapped);
}
EXPORT_SYMBOL_GPL(iommu_unmap);
diff --git a/drivers/iommu/msm_iommu.c b/drivers/iommu/msm_iommu.c
index d1733f6..e59ced9 100644
--- a/drivers/iommu/msm_iommu.c
+++ b/drivers/iommu/msm_iommu.c
@@ -676,6 +676,9 @@ fail:
return 0;
}
+/* bitmap of the page sizes currently supported */
+static unsigned long msm_iommu_pgsizes = SZ_4K | SZ_64K | SZ_1M | SZ_16M;
+
static struct iommu_ops msm_iommu_ops = {
.domain_init = msm_iommu_domain_init,
.domain_destroy = msm_iommu_domain_destroy,
@@ -728,7 +731,10 @@ static void __init setup_iommu_tex_classes(void)
static int __init msm_iommu_init(void)
{
setup_iommu_tex_classes();
- register_iommu(&msm_iommu_ops);
+
+ /* we're only using the first 25 bits of the pgsizes bitmap */
+ register_iommu(&msm_iommu_ops, &msm_iommu_pgsizes, 25);
+
return 0;
}
diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
index 089fddc..3e651f9 100644
--- a/drivers/iommu/omap-iommu.c
+++ b/drivers/iommu/omap-iommu.c
@@ -1202,6 +1202,9 @@ static int omap_iommu_domain_has_cap(struct iommu_domain *domain,
return 0;
}
+/* bitmap of the page sizes supported by the OMAP IOMMU hardware */
+static unsigned long omap_iommu_pgsizes = SZ_4K | SZ_64K | SZ_1M | SZ_16M;
+
static struct iommu_ops omap_iommu_ops = {
.domain_init = omap_iommu_domain_init,
.domain_destroy = omap_iommu_domain_destroy,
@@ -1225,7 +1228,8 @@ static int __init omap_iommu_init(void)
return -ENOMEM;
iopte_cachep = p;
- register_iommu(&omap_iommu_ops);
+ /* we're only using the first 25 bits of the pgsizes bitmap */
+ register_iommu(&omap_iommu_ops, &omap_iommu_pgsizes, 25);
return platform_driver_register(&omap_iommu_driver);
}
diff --git a/drivers/iommu/omap-iovmm.c b/drivers/iommu/omap-iovmm.c
index e8fdb88..f4dea5a 100644
--- a/drivers/iommu/omap-iovmm.c
+++ b/drivers/iommu/omap-iovmm.c
@@ -409,7 +409,6 @@ static int map_iovm_area(struct iommu_domain *domain, struct iovm_struct *new,
unsigned int i, j;
struct scatterlist *sg;
u32 da = new->da_start;
- int order;
if (!domain || !sgt)
return -EINVAL;
@@ -428,12 +427,10 @@ static int map_iovm_area(struct iommu_domain *domain, struct iovm_struct *new,
if (bytes_to_iopgsz(bytes) < 0)
goto err_out;
- order = get_order(bytes);
-
pr_debug("%s: [%d] %08x %08x(%x)\n", __func__,
i, da, pa, bytes);
- err = iommu_map(domain, da, pa, order, flags);
+ err = iommu_map(domain, da, pa, bytes, flags);
if (err)
goto err_out;
@@ -448,10 +445,9 @@ err_out:
size_t bytes;
bytes = sg->length + sg->offset;
- order = get_order(bytes);
/* ignore failures.. we're already handling one */
- iommu_unmap(domain, da, order);
+ iommu_unmap(domain, da, bytes);
da += bytes;
}
@@ -474,12 +470,10 @@ static void unmap_iovm_area(struct iommu_domain *domain, struct omap_iommu *obj,
start = area->da_start;
for_each_sg(sgt->sgl, sg, sgt->nents, i) {
size_t bytes;
- int order;
bytes = sg->length + sg->offset;
- order = get_order(bytes);
- err = iommu_unmap(domain, start, order);
+ err = iommu_unmap(domain, start, bytes);
if (err < 0)
break;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 3cbea04..116d207 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -69,7 +69,8 @@ struct iommu_ops {
#ifdef CONFIG_IOMMU_API
-extern void register_iommu(struct iommu_ops *ops);
+extern void register_iommu(struct iommu_ops *ops, unsigned long *pgsize_bitmap,
+ unsigned int nr_page_bits);
extern bool iommu_found(void);
extern struct iommu_domain *iommu_domain_alloc(iommu_fault_handler_t handler);
extern void iommu_domain_free(struct iommu_domain *domain);
@@ -78,9 +79,9 @@ extern int iommu_attach_device(struct iommu_domain *domain,
extern void iommu_detach_device(struct iommu_domain *domain,
struct device *dev);
extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
- phys_addr_t paddr, int gfp_order, int prot);
+ phys_addr_t paddr, size_t size, int prot);
extern int iommu_unmap(struct iommu_domain *domain, unsigned long iova,
- int gfp_order);
+ size_t size);
extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain,
unsigned long iova);
extern int iommu_domain_has_cap(struct iommu_domain *domain,
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index 2fd67e5..3d107b9 100644
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -111,7 +111,7 @@ int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot)
/* Map into IO address space */
r = iommu_map(domain, gfn_to_gpa(gfn), pfn_to_hpa(pfn),
- get_order(page_size), flags);
+ page_size, flags);
if (r) {
printk(KERN_ERR "kvm_iommu_map_address:"
"iommu failed to map pfn=%llx\n", pfn);
@@ -293,7 +293,7 @@ static void kvm_iommu_put_pages(struct kvm *kvm,
pfn = phys >> PAGE_SHIFT;
/* Unmap address from IO address space */
- order = iommu_unmap(domain, gfn_to_gpa(gfn), 0);
+ order = iommu_unmap(domain, gfn_to_gpa(gfn), PAGE_SIZE);
unmap_pages = 1ULL << order;
/* Unpin all pages we just unmapped to not leak any memory */
--
1.7.4.1
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