[PATCH 05/10] KVM: x86: MMU: Use for_each_rmap_spte macro instead of pte_list_walk()

From: Takuya Yoshikawa
Date: Thu Nov 12 2015 - 06:39:49 EST


kvm_mmu_mark_parents_unsync() alone uses pte_list_walk(), witch does
nearly the same as the for_each_rmap_spte macro. The only difference
is that is_shadow_present_pte() checks cannot be placed there because
kvm_mmu_mark_parents_unsync() can be called with a new parent pointer
whose entry is not set yet.

By calling mark_unsync() separately for the parent and adding the parent
pointer to the parent_ptes chain later in kvm_mmu_get_page(), the macro
works with no problem.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@xxxxxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 36 +++++++++++++-----------------------
1 file changed, 13 insertions(+), 23 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index e8cfdc4..1691171 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1007,26 +1007,6 @@ static void pte_list_remove(u64 *spte, unsigned long *pte_list)
}
}

-typedef void (*pte_list_walk_fn) (u64 *spte);
-static void pte_list_walk(unsigned long *pte_list, pte_list_walk_fn fn)
-{
- struct pte_list_desc *desc;
- int i;
-
- if (!*pte_list)
- return;
-
- if (!(*pte_list & 1))
- return fn((u64 *)*pte_list);
-
- desc = (struct pte_list_desc *)(*pte_list & ~1ul);
- while (desc) {
- for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i)
- fn(desc->sptes[i]);
- desc = desc->more;
- }
-}
-
static unsigned long *__gfn_to_rmap(gfn_t gfn, int level,
struct kvm_memory_slot *slot)
{
@@ -1741,7 +1721,12 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
static void mark_unsync(u64 *spte);
static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp)
{
- pte_list_walk(&sp->parent_ptes, mark_unsync);
+ u64 *sptep;
+ struct rmap_iterator iter;
+
+ for_each_rmap_spte(&sp->parent_ptes, &iter, sptep) {
+ mark_unsync(sptep);
+ }
}

static void mark_unsync(u64 *spte)
@@ -2111,12 +2096,17 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
if (sp->unsync && kvm_sync_page_transient(vcpu, sp))
break;

- mmu_page_add_parent_pte(vcpu, sp, parent_pte);
if (sp->unsync_children) {
kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
kvm_mmu_mark_parents_unsync(sp);
- } else if (sp->unsync)
+ if (parent_pte)
+ mark_unsync(parent_pte);
+ } else if (sp->unsync) {
kvm_mmu_mark_parents_unsync(sp);
+ if (parent_pte)
+ mark_unsync(parent_pte);
+ }
+ mmu_page_add_parent_pte(vcpu, sp, parent_pte);

__clear_sp_write_flooding_count(sp);
trace_kvm_mmu_get_page(sp, false);
--
2.1.0

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