[PATCH 13/14] KVM: x86/mmu: Remove lpage_is_disallowed() check from set_spte()

Sean Christopherson
2020-01-08T20:27:20Z

Remove the late "lpage is disallowed" check from set_spte() now that the
initial check is performed after acquiring mmu_lock. Fold the guts of
the remaining helper, __mmu_gfn_lpage_is_disallowed(), into
kvm_mmu_hugepage_adjust() to eliminate the unnecessary slot !NULL check.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/mmu/mmu.c | 39 +++------------------------------------
1 file changed, 3 insertions(+), 36 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index f2667fe0dc75..1e4e0ac169a7 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1264,28 +1264,6 @@ static void unaccount_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp)
list_del(&sp->lpage_disallowed_link);
}

-static bool __mmu_gfn_lpage_is_disallowed(gfn_t gfn, int level,
- struct kvm_memory_slot *slot)
-{
- struct kvm_lpage_info *linfo;
-
- if (slot) {
- linfo = lpage_info_slot(gfn, slot, level);
- return !!linfo->disallow_lpage;
- }
-
- return true;
-}
-
-static bool mmu_gfn_lpage_is_disallowed(struct kvm_vcpu *vcpu, gfn_t gfn,
- int level)
-{
- struct kvm_memory_slot *slot;
-
- slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
- return __mmu_gfn_lpage_is_disallowed(gfn, level, slot);
-}
-
static inline bool memslot_valid_for_gpte(struct kvm_memory_slot *slot,
bool no_dirty_log)
{
@@ -3078,18 +3056,6 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
spte |= (u64)pfn << PAGE_SHIFT;

if (pte_access & ACC_WRITE_MASK) {
-
- /*
- * Legacy code to handle an obsolete scenario where a different
- * vcpu creates new sp in the window between this vcpu's query
- * of lpage_is_disallowed() and acquiring mmu_lock. No longer
- * necessary now that lpage_is_disallowed() is called after
- * acquiring mmu_lock.
- */
- if (level > PT_PAGE_TABLE_LEVEL &&
- mmu_gfn_lpage_is_disallowed(vcpu, gfn, level))
- goto done;
-
spte |= PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE;

/*
@@ -3121,7 +3087,6 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
set_pte:
if (mmu_spte_update(sptep, spte))
ret |= SET_SPTE_NEED_REMOTE_TLB_FLUSH;
-done:
return ret;
}

@@ -3309,6 +3274,7 @@ static int kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, gfn_t gfn,
int max_level, kvm_pfn_t *pfnp)
{
struct kvm_memory_slot *slot;
+ struct kvm_lpage_info *linfo;
kvm_pfn_t pfn = *pfnp;
kvm_pfn_t mask;
int level;
@@ -3326,7 +3292,8 @@ static int kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, gfn_t gfn,

max_level = min(max_level, kvm_x86_ops->get_lpage_level());
for ( ; max_level > PT_PAGE_TABLE_LEVEL; max_level--) {
- if (!__mmu_gfn_lpage_is_disallowed(gfn, max_level, slot))
+ linfo = lpage_info_slot(gfn, slot, max_level);
+ if (!linfo->disallow_lpage)
break;
}

--
2.24.1