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Subject[PATCH 2/5] KVM: x86: MMU: Add helper function to clear a bit in unsync child bitmap
Both __mmu_unsync_walk() and mmu_pages_clear_parents() have three line
code which clears a bit in the unsync child bitmap; the former places it
inside a loop block and uses a few goto statements to jump to it.

A new helper function, clear_unsync_child_bit(), makes the code cleaner.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
---
arch/x86/kvm/mmu.c | 36 ++++++++++++++++++------------------
1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index a76bc04..a9622a2 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1806,6 +1806,13 @@ static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp,
return (pvec->nr == KVM_PAGE_ARRAY_NR);
}

+static inline void clear_unsync_child_bit(struct kvm_mmu_page *sp, int idx)
+{
+ --sp->unsync_children;
+ WARN_ON((int)sp->unsync_children < 0);
+ __clear_bit(idx, sp->unsync_child_bitmap);
+}
+
static int __mmu_unsync_walk(struct kvm_mmu_page *sp,
struct kvm_mmu_pages *pvec)
{
@@ -1815,8 +1822,10 @@ static int __mmu_unsync_walk(struct kvm_mmu_page *sp,
struct kvm_mmu_page *child;
u64 ent = sp->spt[i];

- if (!is_shadow_present_pte(ent) || is_large_pte(ent))
- goto clear_child_bitmap;
+ if (!is_shadow_present_pte(ent) || is_large_pte(ent)) {
+ clear_unsync_child_bit(sp, i);
+ continue;
+ }

child = page_header(ent & PT64_BASE_ADDR_MASK);

@@ -1825,28 +1834,21 @@ static int __mmu_unsync_walk(struct kvm_mmu_page *sp,
return -ENOSPC;

ret = __mmu_unsync_walk(child, pvec);
- if (!ret)
- goto clear_child_bitmap;
- else if (ret > 0)
+ if (!ret) {
+ clear_unsync_child_bit(sp, i);
+ continue;
+ } else if (ret > 0) {
nr_unsync_leaf += ret;
- else
+ } else
return ret;
} else if (child->unsync) {
nr_unsync_leaf++;
if (mmu_pages_add(pvec, child, i))
return -ENOSPC;
} else
- goto clear_child_bitmap;
-
- continue;
-
-clear_child_bitmap:
- __clear_bit(i, sp->unsync_child_bitmap);
- sp->unsync_children--;
- WARN_ON((int)sp->unsync_children < 0);
+ clear_unsync_child_bit(sp, i);
}

-
return nr_unsync_leaf;
}

@@ -2009,9 +2011,7 @@ static void mmu_pages_clear_parents(struct mmu_page_path *parents)
if (!sp)
return;

- --sp->unsync_children;
- WARN_ON((int)sp->unsync_children < 0);
- __clear_bit(idx, sp->unsync_child_bitmap);
+ clear_unsync_child_bit(sp, idx);
level++;
} while (level < PT64_ROOT_LEVEL-1 && !sp->unsync_children);
}
--
2.1.0


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