Re: [PATCH][POWERPC] Workaround for iommu page alignment (#2)
> And sloppy of me to not catch it. Anyway: > > Acked-by: Olof Johansson <[EMAIL PROTECTED]> > > I wonder how long until there's a device that has some other < PAGE_SIZE > alignment bug^Wrequirement that we'll need to meet too. :( Yeah, it's a worry... Ben. ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [PATCH][POWERPC] Workaround for iommu page alignment (#2)
On Tue, Jan 08, 2008 at 10:34:22AM +1100, Benjamin Herrenschmidt wrote: > powerpc: Workaround for iommu page alignment > > Our iommu page size is currently always 4K. That means with our current > code, drivers may do a dma_map_sg() of a 64K page and obtain a dma_addr_t > that is only 4K aligned. > > This works fine in most cases except some infiniband HW it seems, where > they tell the HW about the page size and it ignores the low bits of the > DMA address. > > This works around it by making our IOMMU code enforce a PAGE_SIZE alignment > for mappings of objects that are page aligned in the first place and whose > size is larger or equal to a page. > > Signed-off-by: Benjamin Herrenschmidt <[EMAIL PROTECTED]> > --- > > And this version actually does what the comment says (I had forgotten > to quilt ref... a common mistake). And sloppy of me to not catch it. Anyway: Acked-by: Olof Johansson <[EMAIL PROTECTED]> I wonder how long until there's a device that has some other < PAGE_SIZE alignment bug^Wrequirement that we'll need to meet too. :( -Olof ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
[PATCH][POWERPC] Workaround for iommu page alignment (#2)
powerpc: Workaround for iommu page alignment
Our iommu page size is currently always 4K. That means with our current
code, drivers may do a dma_map_sg() of a 64K page and obtain a dma_addr_t
that is only 4K aligned.
This works fine in most cases except some infiniband HW it seems, where
they tell the HW about the page size and it ignores the low bits of the
DMA address.
This works around it by making our IOMMU code enforce a PAGE_SIZE alignment
for mappings of objects that are page aligned in the first place and whose
size is larger or equal to a page.
Signed-off-by: Benjamin Herrenschmidt <[EMAIL PROTECTED]>
---
And this version actually does what the comment says (I had forgotten
to quilt ref... a common mistake).
Index: linux-work/arch/powerpc/kernel/iommu.c
===
--- linux-work.orig/arch/powerpc/kernel/iommu.c 2007-12-21 10:39:39.0
+1100
+++ linux-work/arch/powerpc/kernel/iommu.c 2007-12-21 10:48:12.0
+1100
@@ -278,6 +278,7 @@ int iommu_map_sg(struct iommu_table *tbl
unsigned long flags;
struct scatterlist *s, *outs, *segstart;
int outcount, incount, i;
+ unsigned int align;
unsigned long handle;
BUG_ON(direction == DMA_NONE);
@@ -309,7 +310,12 @@ int iommu_map_sg(struct iommu_table *tbl
/* Allocate iommu entries for that segment */
vaddr = (unsigned long) sg_virt(s);
npages = iommu_num_pages(vaddr, slen);
- entry = iommu_range_alloc(tbl, npages, &handle, mask >>
IOMMU_PAGE_SHIFT, 0);
+ align = 0;
+ if (IOMMU_PAGE_SHIFT < PAGE_SHIFT && slen >= PAGE_SIZE &&
+ (vaddr & ~PAGE_MASK) == 0)
+ align = PAGE_SHIFT - IOMMU_PAGE_SHIFT;
+ entry = iommu_range_alloc(tbl, npages, &handle,
+ mask >> IOMMU_PAGE_SHIFT, align);
DBG(" - vaddr: %lx, size: %lx\n", vaddr, slen);
@@ -572,7 +578,7 @@ dma_addr_t iommu_map_single(struct iommu
{
dma_addr_t dma_handle = DMA_ERROR_CODE;
unsigned long uaddr;
- unsigned int npages;
+ unsigned int npages, align;
BUG_ON(direction == DMA_NONE);
@@ -580,8 +586,13 @@ dma_addr_t iommu_map_single(struct iommu
npages = iommu_num_pages(uaddr, size);
if (tbl) {
+ align = 0;
+ if (IOMMU_PAGE_SHIFT < PAGE_SHIFT && size >= PAGE_SIZE &&
+ ((unsigned long)vaddr & ~PAGE_MASK) == 0)
+ align = PAGE_SHIFT - IOMMU_PAGE_SHIFT;
+
dma_handle = iommu_alloc(tbl, vaddr, npages, direction,
-mask >> IOMMU_PAGE_SHIFT, 0);
+mask >> IOMMU_PAGE_SHIFT, align);
if (dma_handle == DMA_ERROR_CODE) {
if (printk_ratelimit()) {
printk(KERN_INFO "iommu_alloc failed, "
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Re: [PATCH][POWERPC] Workaround for iommu page alignment
> I don't see in the code where you implement the "size > PAGE_SIZE" > condition. But I only just got back from holidays .. :) Indeed ... a "quilt ref" was missing :-( New patch coming ... Ben. ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [PATCH][POWERPC] Workaround for iommu page alignment
On Tue, 2008-01-08 at 08:45 +1100, Benjamin Herrenschmidt wrote: > Our iommu page size is currently always 4K. That means with our current > code, drivers may do a dma_map_sg() of a 64K page and obtain a dma_addr_t > that is only 4K aligned. > > This works fine in most cases except some infiniband HW it seems, where > they tell the HW about the page size and it ignores the low bits of the > DMA address. > > This works around it by making our IOMMU code enforce a PAGE_SIZE alignment > for mappings of objects that are page aligned in the first place and whose > size is larger or equal to a page. ^ I don't see in the code where you implement the "size > PAGE_SIZE" condition. But I only just got back from holidays .. :) cheers -- Michael Ellerman OzLabs, IBM Australia Development Lab wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person signature.asc Description: This is a digitally signed message part ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [PATCH][POWERPC] Workaround for iommu page alignment
On Tue, Jan 08, 2008 at 08:45:59AM +1100, Benjamin Herrenschmidt wrote: > Our iommu page size is currently always 4K. That means with our current > code, drivers may do a dma_map_sg() of a 64K page and obtain a dma_addr_t > that is only 4K aligned. > > This works fine in most cases except some infiniband HW it seems, where > they tell the HW about the page size and it ignores the low bits of the > DMA address. > > This works around it by making our IOMMU code enforce a PAGE_SIZE alignment > for mappings of objects that are page aligned in the first place and whose > size is larger or equal to a page. > > Signed-off-by: Benjamin Herrenschmidt <[EMAIL PROTECTED]> Acked-by: Olof Johansson <[EMAIL PROTECTED]> -Olof ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
[PATCH][POWERPC] Workaround for iommu page alignment
Our iommu page size is currently always 4K. That means with our current
code, drivers may do a dma_map_sg() of a 64K page and obtain a dma_addr_t
that is only 4K aligned.
This works fine in most cases except some infiniband HW it seems, where
they tell the HW about the page size and it ignores the low bits of the
DMA address.
This works around it by making our IOMMU code enforce a PAGE_SIZE alignment
for mappings of objects that are page aligned in the first place and whose
size is larger or equal to a page.
Signed-off-by: Benjamin Herrenschmidt <[EMAIL PROTECTED]>
---
Looks like it fell through the holiday cracks ...
It could still go in 2.6.24 I suppose... If not, put it in 2.6.25 and
we'll backport to stable later.
Index: linux-work/arch/powerpc/kernel/iommu.c
===
--- linux-work.orig/arch/powerpc/kernel/iommu.c 2007-12-21 10:39:39.0
+1100
+++ linux-work/arch/powerpc/kernel/iommu.c 2007-12-21 10:46:18.0
+1100
@@ -278,6 +278,7 @@ int iommu_map_sg(struct iommu_table *tbl
unsigned long flags;
struct scatterlist *s, *outs, *segstart;
int outcount, incount, i;
+ unsigned int align;
unsigned long handle;
BUG_ON(direction == DMA_NONE);
@@ -309,7 +310,11 @@ int iommu_map_sg(struct iommu_table *tbl
/* Allocate iommu entries for that segment */
vaddr = (unsigned long) sg_virt(s);
npages = iommu_num_pages(vaddr, slen);
- entry = iommu_range_alloc(tbl, npages, &handle, mask >>
IOMMU_PAGE_SHIFT, 0);
+ align = 0;
+ if (IOMMU_PAGE_SHIFT < PAGE_SHIFT && (vaddr & ~PAGE_MASK) == 0)
+ align = PAGE_SHIFT - IOMMU_PAGE_SHIFT;
+ entry = iommu_range_alloc(tbl, npages, &handle,
+ mask >> IOMMU_PAGE_SHIFT, align);
DBG(" - vaddr: %lx, size: %lx\n", vaddr, slen);
@@ -572,7 +577,7 @@ dma_addr_t iommu_map_single(struct iommu
{
dma_addr_t dma_handle = DMA_ERROR_CODE;
unsigned long uaddr;
- unsigned int npages;
+ unsigned int npages, align;
BUG_ON(direction == DMA_NONE);
@@ -580,8 +585,13 @@ dma_addr_t iommu_map_single(struct iommu
npages = iommu_num_pages(uaddr, size);
if (tbl) {
+ align = 0;
+ if (IOMMU_PAGE_SHIFT < PAGE_SHIFT &&
+ ((unsigned long)vaddr & ~PAGE_MASK) == 0)
+ align = PAGE_SHIFT - IOMMU_PAGE_SHIFT;
+
dma_handle = iommu_alloc(tbl, vaddr, npages, direction,
-mask >> IOMMU_PAGE_SHIFT, 0);
+mask >> IOMMU_PAGE_SHIFT, align);
if (dma_handle == DMA_ERROR_CODE) {
if (printk_ratelimit()) {
printk(KERN_INFO "iommu_alloc failed, "
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