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vfio/type1: Chunk contiguous reserved/invalid page mappings 

We currently map invalid and reserved pages, such as often occur from
mapping MMIO regions of a VM through the IOMMU, using single pages.
There's really no reason we can't instead follow the methodology we
use for normal pages and find the largest possible physically
contiguous chunk for mapping.  The only difference is that we don't
do locked memory accounting for these since they're not back by RAM.

In most applications this will be a very minor improvement, but when
graphics and GPGPU devices are in play, MMIO BARs become non-trivial.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2015-02-06 10:59:16 -07:00
parent 6fe1010d6d
commit babbf17609
1 changed files with 11 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/vfio/vfio_iommu_type1.c
View File

@ -265,6 +265,7 @@ static long vfio_pin_pages(unsigned long vaddr, long npage,
unsigned long limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
bool lock_cap = capable(CAP_IPC_LOCK);
long ret, i;
bool rsvd;
if (!current->mm)
return -ENODEV;
@ -273,10 +274,9 @@ static long vfio_pin_pages(unsigned long vaddr, long npage,
if (ret)
return ret;
if (is_invalid_reserved_pfn(*pfn_base))
return 1;
rsvd = is_invalid_reserved_pfn(*pfn_base);
if (!lock_cap && current->mm->locked_vm + 1 > limit) {
if (!rsvd && !lock_cap && current->mm->locked_vm + 1 > limit) {
put_pfn(*pfn_base, prot);
pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", __func__,
limit << PAGE_SHIFT);
@ -284,7 +284,8 @@ static long vfio_pin_pages(unsigned long vaddr, long npage,
}
if (unlikely(disable_hugepages)) {
vfio_lock_acct(1);
if (!rsvd)
vfio_lock_acct(1);
return 1;
}
@ -296,12 +297,14 @@ static long vfio_pin_pages(unsigned long vaddr, long npage,
if (ret)
break;
if (pfn != *pfn_base + i || is_invalid_reserved_pfn(pfn)) {
if (pfn != *pfn_base + i ||
rsvd != is_invalid_reserved_pfn(pfn)) {
put_pfn(pfn, prot);
break;
}
if (!lock_cap && current->mm->locked_vm + i + 1 > limit) {
if (!rsvd && !lock_cap &&
current->mm->locked_vm + i + 1 > limit) {
put_pfn(pfn, prot);
pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n",
__func__, limit << PAGE_SHIFT);
@ -309,7 +312,8 @@ static long vfio_pin_pages(unsigned long vaddr, long npage,
}
}
vfio_lock_acct(i);
if (!rsvd)
vfio_lock_acct(i);
return i;
}