[PATCH 2/4] KVM: introduce helper to access lpage_info

[Takuya Yoshikawa]

The index calculation for accessing lpage_info appears a few times.
This patch replaces these with a new lpage_idx() helper.

Signed-off-by: Takuya Yoshikawa <yoshikawa.tak...@oss.ntt.co.jp>
---
 arch/x86/kvm/mmu.c |   20 +++++++++++---------
 1 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index e716def..2139309 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -476,6 +476,12 @@ static void kvm_mmu_page_set_gfn(struct kvm_mmu_page *sp, 
int index, gfn_t gfn)
                sp->gfns[index] = gfn;
 }
 
+static unsigned long lpage_idx(gfn_t gfn, gfn_t base_gfn, int level)
+{
+       return (gfn >> KVM_HPAGE_GFN_SHIFT(level)) -
+              (base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
+}
+
 /*
  * Return the pointer to the largepage write count for a given
  * gfn, handling slots that are not large page aligned.
@@ -484,10 +490,8 @@ static int *slot_largepage_idx(gfn_t gfn,
                               struct kvm_memory_slot *slot,
                               int level)
 {
-       unsigned long idx;
+       unsigned long idx = lpage_idx(gfn, slot->base_gfn, level);
 
-       idx = (gfn >> KVM_HPAGE_GFN_SHIFT(level)) -
-             (slot->base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
        return &slot->lpage_info[level - 2][idx].write_count;
 }
 
@@ -591,8 +595,7 @@ static unsigned long *gfn_to_rmap(struct kvm *kvm, gfn_t 
gfn, int level)
        if (likely(level == PT_PAGE_TABLE_LEVEL))
                return &slot->rmap[gfn - slot->base_gfn];
 
-       idx = (gfn >> KVM_HPAGE_GFN_SHIFT(level)) -
-               (slot->base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
+       idx = lpage_idx(gfn, slot->base_gfn, level);
 
        return &slot->lpage_info[level - 2][idx].rmap_pde;
 }
@@ -887,11 +890,10 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long 
hva,
 
                        for (j = 0; j < KVM_NR_PAGE_SIZES - 1; ++j) {
                                unsigned long idx;
-                               int sh;
 
-                               sh = KVM_HPAGE_GFN_SHIFT(PT_DIRECTORY_LEVEL+j);
-                               idx = ((memslot->base_gfn+gfn_offset) >> sh) -
-                                       (memslot->base_gfn >> sh);
+                               idx = lpage_idx(memslot->base_gfn + gfn_offset,
+                                               memslot->base_gfn,
+                                               PT_DIRECTORY_LEVEL + j);
                                ret |= handler(kvm,
                                        &memslot->lpage_info[j][idx].rmap_pde,
                                        data);
-- 
1.7.1

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