On 25/05/16 00:06, Wei Yang wrote:
Hi, Joerg
Not sure whether you think this calculation is correct.
If I missed something for this " + 1" in your formula, I am glad to hear your
explanation. So that I could learn something from you :-)
I'm not familiar enough with this aspect of the driver to confirm
whether the change is appropriate or not, but it does seem worth noting
that using DIV_ROUND_UP would be an even neater approach.
Robin.
Have a good day~
On Sat, May 21, 2016 at 02:41:51AM +0000, Wei Yang wrote:
In commit <8bf478163e69> ("iommu/vt-d: Split up iommu->domains array"), it
it splits iommu->domains in two levels. Each first level contains 256
entries of second level. In case of the ndomains is exact a multiple of
256, it would have one more extra first level entry for current
implementation.
This patch refines this calculation to reduce the extra first level entry.
Signed-off-by: Wei Yang <[email protected]>
---
drivers/iommu/intel-iommu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index e3061d3..2204ca4 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1634,7 +1634,7 @@ static int iommu_init_domains(struct intel_iommu *iommu)
return -ENOMEM;
}
- size = ((ndomains >> 8) + 1) * sizeof(struct dmar_domain **);
+ size = (ALIGN(ndomains, 256) >> 8) * sizeof(struct dmar_domain **);
iommu->domains = kzalloc(size, GFP_KERNEL);
if (iommu->domains) {
@@ -1699,7 +1699,7 @@ static void disable_dmar_iommu(struct intel_iommu *iommu)
static void free_dmar_iommu(struct intel_iommu *iommu)
{
if ((iommu->domains) && (iommu->domain_ids)) {
- int elems = (cap_ndoms(iommu->cap) >> 8) + 1;
+ int elems = ALIGN(cap_ndoms(iommu->cap), 256) >> 8;
int i;
for (i = 0; i < elems; i++)
--
1.7.9.5
