Re: [PATCH kernel v7 04/31] vfio: powerpc/spapr: Use it_page_size

[Alexey Kardashevskiy]

On 04/02/2015 08:48 AM, Alex Williamson wrote:
On Sat, 2015-03-28 at 01:54 +1100, Alexey Kardashevskiy wrote:
This makes use of the it_page_size from the iommu_table struct
as page size can differ.
This replaces missing IOMMU_PAGE_SHIFT macro in commented debug code
as recently introduced IOMMU_PAGE_XXX macros do not include
IOMMU_PAGE_SHIFT.

Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
---
  drivers/vfio/vfio_iommu_spapr_tce.c | 26 +++++++++++++-------------
  1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c 
b/drivers/vfio/vfio_iommu_spapr_tce.c
index f835e63..8bbee22 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -91,7 +91,7 @@ static int tce_iommu_enable(struct tce_container *container)
         * 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_4K) >> PAGE_SHIFT;
+       npages = (tbl->it_size << tbl->it_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)) {
@@ -120,7 +120,7 @@ static void tce_iommu_disable(struct tce_container 
*container)

        down_write(&current->mm->mmap_sem);
        current->mm->locked_vm -= (container->tbl->it_size <<
-                       IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT;
+                       container->tbl->it_page_shift) >> PAGE_SHIFT;
        up_write(&current->mm->mmap_sem);
  }

@@ -222,7 +222,7 @@ static long tce_iommu_build(struct tce_container *container,
                                        tce, ret);
                        break;
                }
-               tce += IOMMU_PAGE_SIZE_4K;
+               tce += IOMMU_PAGE_SIZE(tbl);


Is PAGE_SIZE ever smaller than IOMMU_PAGE_SIZE(tbl)?  IOW, can the page
we got from get_user_pages_fast() ever not completely fill the tce
entry?


Yes. IOMMU_PAGE_SIZE is 4K/64K/16M (16M is with huge pages enabled in QEMU 
with -mempath), PAGE_SIZE is 4K/64K (normally 64K).


(Have I asked this before?  Sorry if so)


:)



--
Alexey
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