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authorAlex Williamson <alex.williamson@redhat.com>2017-04-18 01:07:06 +0300
committerAlex Williamson <alex.williamson@redhat.com>2017-04-19 00:01:15 +0300
commit7cb671e7a34d73b29df77d0b53492277744e57e7 (patch)
treec8ec48571db212aabe91b5fc77a20fb8277d78a0
parent80dbe1fbafbf469fd19862f0d400b769bff0ee46 (diff)
downloadlinux-7cb671e7a34d73b29df77d0b53492277744e57e7.tar.xz
vfio/type1: Reduce repetitive calls in vfio_pin_pages_remote()
vfio_pin_pages_remote() is typically called to iterate over a range of memory. Testing CAP_IPC_LOCK is relatively expensive, so it makes sense to push it up to the caller, which can then repeatedly call vfio_pin_pages_remote() using that value. This can show nearly a 20% improvement on the worst case path through VFIO_IOMMU_MAP_DMA with contiguous page mapping disabled. Testing RLIMIT_MEMLOCK is much more lightweight, but we bring it along on the same principle and it does seem to show a marginal improvement. Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
-rw-r--r--drivers/vfio/vfio_iommu_type1.c17
1 files changed, 11 insertions, 6 deletions
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 372e4f626138..8549cb111627 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -380,10 +380,10 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
* first page and all consecutive pages with the same locking.
*/
static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr,
- long npage, unsigned long *pfn_base)
+ long npage, unsigned long *pfn_base,
+ bool lock_cap, unsigned long limit)
{
- unsigned long pfn = 0, limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
- bool lock_cap = capable(CAP_IPC_LOCK);
+ unsigned long pfn = 0;
long ret, pinned = 0, lock_acct = 0;
bool rsvd;
dma_addr_t iova = vaddr - dma->vaddr + dma->iova;
@@ -924,13 +924,15 @@ static int vfio_pin_map_dma(struct vfio_iommu *iommu, struct vfio_dma *dma,
unsigned long vaddr = dma->vaddr;
size_t size = map_size;
long npage;
- unsigned long pfn;
+ unsigned long pfn, limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+ bool lock_cap = capable(CAP_IPC_LOCK);
int ret = 0;
while (size) {
/* Pin a contiguous chunk of memory */
npage = vfio_pin_pages_remote(dma, vaddr + dma->size,
- size >> PAGE_SHIFT, &pfn);
+ size >> PAGE_SHIFT, &pfn,
+ lock_cap, limit);
if (npage <= 0) {
WARN_ON(!npage);
ret = (int)npage;
@@ -1040,6 +1042,8 @@ static int vfio_iommu_replay(struct vfio_iommu *iommu,
{
struct vfio_domain *d;
struct rb_node *n;
+ unsigned long limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+ bool lock_cap = capable(CAP_IPC_LOCK);
int ret;
/* Arbitrarily pick the first domain in the list for lookups */
@@ -1086,7 +1090,8 @@ static int vfio_iommu_replay(struct vfio_iommu *iommu,
npage = vfio_pin_pages_remote(dma, vaddr,
n >> PAGE_SHIFT,
- &pfn);
+ &pfn, lock_cap,
+ limit);
if (npage <= 0) {
WARN_ON(!npage);
ret = (int)npage;