KVM: Remove unnecessary divide operations

This patch converts unnecessary divide and modulo operations
in the KVM large page related code into logical operations.
This allows to convert gfn_t to u64 while not breaking 32
bit builds.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ec2e3c6ac7e..a60b6b053b6 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -626,9 +626,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
                 if (new.lpage_info[i])
                         continue;
 
-                lpages = 1 + (base_gfn + npages - 1) /
-                             KVM_PAGES_PER_HPAGE(level);
-                lpages -= base_gfn / KVM_PAGES_PER_HPAGE(level);
+                lpages = 1 + ((base_gfn + npages - 1)
+                             >> KVM_HPAGE_GFN_SHIFT(level));
+                lpages -= base_gfn >> KVM_HPAGE_GFN_SHIFT(level);
 
                 new.lpage_info[i] = vmalloc(lpages * sizeof(*new.lpage_info[i]));
 
@@ -638,9 +638,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
                 memset(new.lpage_info[i], 0,
                        lpages * sizeof(*new.lpage_info[i]));
 
-                if (base_gfn % KVM_PAGES_PER_HPAGE(level))
+                if (base_gfn & (KVM_PAGES_PER_HPAGE(level) - 1))
                         new.lpage_info[i][0].write_count = 1;
-                if ((base_gfn+npages) % KVM_PAGES_PER_HPAGE(level))
+                if ((base_gfn+npages) & (KVM_PAGES_PER_HPAGE(level) - 1))
                         new.lpage_info[i][lpages - 1].write_count = 1;
                 ugfn = new.userspace_addr >> PAGE_SHIFT;
                 /*