linux-kernel - [PATCH 2/2] KVM: X86: Remove the present check from for_each_shadow

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Date:   Thu, 12 Aug 2021 12:36:30 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Lai Jiangshan <laijs@...ux.alibaba.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        kvm@...r.kernel.org
Subject: [PATCH 2/2] KVM: X86: Remove the present check from for_each_shadow_entry* loop body

From: Lai Jiangshan <laijs@...ux.alibaba.com>

The function __shadow_walk_next() for the for_each_shadow_entry* looping
has the check and propagates the result to shadow_walk_okay().

Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
---
 arch/x86/kvm/mmu/mmu.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index c48ecb25d5f8..42eebba6782e 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3152,9 +3152,6 @@ static u64 *fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, gpa_t gpa, u64 *spte)
 	for_each_shadow_entry_lockless(vcpu, gpa, iterator, old_spte) {
 		sptep = iterator.sptep;
 		*spte = old_spte;
-
-		if (!is_shadow_present_pte(old_spte))
-			break;
 	}
 
 	return sptep;
@@ -3694,9 +3691,6 @@ static int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level
 		spte = mmu_spte_get_lockless(iterator.sptep);
 
 		sptes[leaf] = spte;
-
-		if (!is_shadow_present_pte(spte))
-			break;
 	}
 
 	return leaf;
@@ -3811,11 +3805,8 @@ static void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr)
 	u64 spte;
 
 	walk_shadow_page_lockless_begin(vcpu);
-	for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) {
+	for_each_shadow_entry_lockless(vcpu, addr, iterator, spte)
 		clear_sp_write_flooding_count(iterator.sptep);
-		if (!is_shadow_present_pte(spte))
-			break;
-	}
 	walk_shadow_page_lockless_end(vcpu);
 }
 
-- 
2.19.1.6.gb485710b