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Subject[PATCH 25/40] KVM: MMU: Add for_each_shadow_entry(), a simpler alternative to walk_shadow()
Date
Using a for_each loop style removes the need to write callback and nasty
casts.

Implement the walk_shadow() using the for_each_shadow_entry().

Signed-off-by: Avi Kivity <avi@redhat.com>
---
arch/x86/kvm/mmu.c | 69 +++++++++++++++++++++++++++++++++++++---------------
1 files changed, 49 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 5f03ec3..c669f2a 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -150,6 +150,20 @@ struct kvm_shadow_walk {
u64 addr, u64 *spte, int level);
};

+struct kvm_shadow_walk_iterator {
+ u64 addr;
+ hpa_t shadow_addr;
+ int level;
+ u64 *sptep;
+ unsigned index;
+};
+
+#define for_each_shadow_entry(_vcpu, _addr, _walker) \
+ for (shadow_walk_init(&(_walker), _vcpu, _addr); \
+ shadow_walk_okay(&(_walker)); \
+ shadow_walk_next(&(_walker)))
+
+
struct kvm_unsync_walk {
int (*entry) (struct kvm_mmu_page *sp, struct kvm_unsync_walk *walk);
};
@@ -1254,33 +1268,48 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
return sp;
}

+static void shadow_walk_init(struct kvm_shadow_walk_iterator *iterator,
+ struct kvm_vcpu *vcpu, u64 addr)
+{
+ iterator->addr = addr;
+ iterator->shadow_addr = vcpu->arch.mmu.root_hpa;
+ iterator->level = vcpu->arch.mmu.shadow_root_level;
+ if (iterator->level == PT32E_ROOT_LEVEL) {
+ iterator->shadow_addr
+ = vcpu->arch.mmu.pae_root[(addr >> 30) & 3];
+ iterator->shadow_addr &= PT64_BASE_ADDR_MASK;
+ --iterator->level;
+ if (!iterator->shadow_addr)
+ iterator->level = 0;
+ }
+}
+
+static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator)
+{
+ if (iterator->level < PT_PAGE_TABLE_LEVEL)
+ return false;
+ iterator->index = SHADOW_PT_INDEX(iterator->addr, iterator->level);
+ iterator->sptep = ((u64 *)__va(iterator->shadow_addr)) + iterator->index;
+ return true;
+}
+
+static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator)
+{
+ iterator->shadow_addr = *iterator->sptep & PT64_BASE_ADDR_MASK;
+ --iterator->level;
+}
+
static int walk_shadow(struct kvm_shadow_walk *walker,
struct kvm_vcpu *vcpu, u64 addr)
{
- hpa_t shadow_addr;
- int level;
+ struct kvm_shadow_walk_iterator iterator;
int r;
- u64 *sptep;
- unsigned index;
-
- shadow_addr = vcpu->arch.mmu.root_hpa;
- level = vcpu->arch.mmu.shadow_root_level;
- if (level == PT32E_ROOT_LEVEL) {
- shadow_addr = vcpu->arch.mmu.pae_root[(addr >> 30) & 3];
- shadow_addr &= PT64_BASE_ADDR_MASK;
- if (!shadow_addr)
- return 1;
- --level;
- }

- while (level >= PT_PAGE_TABLE_LEVEL) {
- index = SHADOW_PT_INDEX(addr, level);
- sptep = ((u64 *)__va(shadow_addr)) + index;
- r = walker->entry(walker, vcpu, addr, sptep, level);
+ for_each_shadow_entry(vcpu, addr, iterator) {
+ r = walker->entry(walker, vcpu, addr,
+ iterator.sptep, iterator.level);
if (r)
return r;
- shadow_addr = *sptep & PT64_BASE_ADDR_MASK;
- --level;
}
return 0;
}
--
1.6.0.6


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