[PATCH v2 17/22] KVM: MMU: clean up spte updating and clearing

Xiao Guangrong
2011-06-22T14:34:53Z

Clean up the code between mmu_spte_clear_* and mmu_spte_update

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
arch/x86/kvm/mmu.c | 75 +++++++++++++++++++++++++++-------------------------
1 files changed, 39 insertions(+), 36 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 5ceb64a..339e1a3 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -279,24 +279,51 @@ static u64 __xchg_spte(u64 *sptep, u64 new_spte)
#endif
}

-static bool spte_has_volatile_bits(u64 spte)
+static bool spte_is_bit_cleared(u64 old_spte, u64 new_spte, u64 bit_mask)
+{
+ return (old_spte & bit_mask) && !(new_spte & bit_mask);
+}
+
+static bool spte_has_volatile_bits(u64 spte, u64 keep_bits)
{
+ bool access_nonvolatile = false, dirty_nonvolatile = false;
+
if (!shadow_accessed_mask)
return false;

- if (!is_shadow_present_pte(spte))
- return false;
+ if ((spte | keep_bits) & shadow_accessed_mask)
+ access_nonvolatile = true;
+
+ if (!is_writable_pte(spte) || ((spte | keep_bits) & shadow_dirty_mask))
+ dirty_nonvolatile = true;

- if ((spte & shadow_accessed_mask) &&
- (!is_writable_pte(spte) || (spte & shadow_dirty_mask)))
+ if (access_nonvolatile && dirty_nonvolatile)
return false;

return true;
}

-static bool spte_is_bit_cleared(u64 old_spte, u64 new_spte, u64 bit_mask)
+static void track_spte_bits(u64 old_spte, u64 keep_bits, bool always_track)
{
- return (old_spte & bit_mask) && !(new_spte & bit_mask);
+ if (always_track ||
+ (spte_is_bit_cleared(old_spte, keep_bits, shadow_accessed_mask)))
+ kvm_set_pfn_accessed(spte_to_pfn(old_spte));
+
+ if (always_track ||
+ (spte_is_bit_cleared(old_spte, keep_bits, shadow_dirty_mask)))
+ kvm_set_pfn_dirty(spte_to_pfn(old_spte));
+}
+
+static u64 spte_get_and_update_clear(u64 *sptep, u64 new_spte)
+{
+ u64 old_spte = *sptep;
+
+ if (!spte_has_volatile_bits(old_spte, new_spte))
+ __set_spte(sptep, new_spte);
+ else
+ old_spte = __xchg_spte(sptep, new_spte);
+
+ return old_spte;
}

/* Rules for using mmu_spte_set:
@@ -316,7 +343,7 @@ static void mmu_spte_set(u64 *sptep, u64 new_spte)
*/
static void mmu_spte_update(u64 *sptep, u64 new_spte)
{
- u64 mask, old_spte = *sptep;
+ u64 old_spte = *sptep;

WARN_ON(!is_rmap_spte(new_spte));

@@ -324,23 +351,8 @@ static void mmu_spte_update(u64 *sptep, u64 new_spte)
return mmu_spte_set(sptep, new_spte);

new_spte |= old_spte & shadow_dirty_mask;
-
- mask = shadow_accessed_mask;
- if (is_writable_pte(old_spte))
- mask |= shadow_dirty_mask;
-
- if (!spte_has_volatile_bits(old_spte) || (new_spte & mask) == mask)
- __set_spte(sptep, new_spte);
- else
- old_spte = __xchg_spte(sptep, new_spte);
-
- if (!shadow_accessed_mask)
- return;
-
- if (spte_is_bit_cleared(old_spte, new_spte, shadow_accessed_mask))
- kvm_set_pfn_accessed(spte_to_pfn(old_spte));
- if (spte_is_bit_cleared(old_spte, new_spte, shadow_dirty_mask))
- kvm_set_pfn_dirty(spte_to_pfn(old_spte));
+ old_spte = spte_get_and_update_clear(sptep, new_spte);
+ track_spte_bits(old_spte, new_spte, false);
}

/*
@@ -350,22 +362,13 @@ static void mmu_spte_update(u64 *sptep, u64 new_spte)
*/
static int mmu_spte_clear_track_bits(u64 *sptep)
{
- pfn_t pfn;
u64 old_spte = *sptep;

- if (!spte_has_volatile_bits(old_spte))
- __set_spte(sptep, 0ull);
- else
- old_spte = __xchg_spte(sptep, 0ull);
-
if (!is_rmap_spte(old_spte))
return 0;

- pfn = spte_to_pfn(old_spte);
- if (!shadow_accessed_mask || old_spte & shadow_accessed_mask)
- kvm_set_pfn_accessed(pfn);
- if (!shadow_dirty_mask || (old_spte & shadow_dirty_mask))
- kvm_set_pfn_dirty(pfn);
+ old_spte = spte_get_and_update_clear(sptep, 0ull);
+ track_spte_bits(old_spte, 0ull, !shadow_accessed_mask);
return 1;
}

--
1.7.5.4