linux-kernel - [PATCH 13/14] KVM: x86/mmu: Remove lpage_is_disallowed() check from set

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Date:   Wed,  8 Jan 2020 12:24:47 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Paul Mackerras <paulus@...abs.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        kvm-ppc@...r.kernel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        syzbot+c9d1fb51ac9d0d10c39d@...kaller.appspotmail.com,
        Andrea Arcangeli <aarcange@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Barret Rhoden <brho@...gle.com>,
        David Hildenbrand <david@...hat.com>,
        Jason Zeng <jason.zeng@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Liran Alon <liran.alon@...cle.com>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>
Subject: [PATCH 13/14] KVM: x86/mmu: Remove lpage_is_disallowed() check from set_spte()

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@...el.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