[10/12] KVM: X86/MMU: Don't add parents to struct kvm_mmu_pages

Commit Message

Lai Jiangshan June 5, 2022, 6:43 a.m. UTC

From: Lai Jiangshan <[e-mail]>

Parents added into the struct kvm_mmu_pages are never used.

Signed-off-by: Lai Jiangshan <[e-mail]>
---
 arch/x86/kvm/mmu/mmu.c | 36 +++++-------------------------------
 1 file changed, 5 insertions(+), 31 deletions(-)

Comments

Sean Christopherson July 19, 2022, 8:34 p.m. UTC | #1

On Sun, Jun 05, 2022, Lai Jiangshan wrote:
> From: Lai Jiangshan <[e-mail]>
> 
> Parents added into the struct kvm_mmu_pages are never used.

s/never/no longer, and if possible, exapnd on why they are no longer used.  Most
of that can be gleaned from prior patches, but capturing the high level historical
details isn't that onerous.

Patch

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index a5563e5ee2e5..304a515bd073 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1751,10 +1751,9 @@  static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp)
 {
 	int i;
 
-	if (sp->unsync)
-		for (i=0; i < pvec->nr; i++)
-			if (pvec->sp[i] == sp)
-				return 0;
+	for (i=0; i < pvec->nr; i++)
+		if (pvec->sp[i] == sp)
+			return 0;
 
 	pvec->sp[pvec->nr] = sp;
 	pvec->nr++;
@@ -1785,9 +1784,6 @@  static int __mmu_unsync_walk_and_clear(struct kvm_mmu_page *sp,
 		child = to_shadow_page(ent & PT64_BASE_ADDR_MASK);
 
 		if (child->unsync_children) {
-			if (mmu_pages_add(pvec, child))
-				return -ENOSPC;
-
 			ret = __mmu_unsync_walk_and_clear(child, pvec);
 			if (ret < 0)
 				return ret;
@@ -1818,7 +1814,6 @@  static int mmu_unsync_walk_and_clear(struct kvm_mmu_page *sp,
 	if (!sp->unsync_children)
 		return 0;
 
-	mmu_pages_add(pvec, sp);
 	return __mmu_unsync_walk_and_clear(sp, pvec);
 }
 
@@ -1897,33 +1892,12 @@  static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
 
 static int mmu_pages_next(struct kvm_mmu_pages *pvec, int i)
 {
-	int n;
-
-	for (n = i+1; n < pvec->nr; n++) {
-		struct kvm_mmu_page *sp = pvec->sp[n];
-		int level = sp->role.level;
-
-		if (level == PG_LEVEL_4K)
-			break;
-
-	}
-
-	return n;
+	return i + 1;
 }
 
 static int mmu_pages_first(struct kvm_mmu_pages *pvec)
 {
-	struct kvm_mmu_page *sp;
-	int level;
-
-	if (pvec->nr == 0)
-		return 0;
-
-	sp = pvec->sp[0];
-	level = sp->role.level;
-	WARN_ON(level == PG_LEVEL_4K);
-
-	return mmu_pages_next(pvec, 0);
+	return 0;
 }
 
 static int mmu_sync_children(struct kvm_vcpu *vcpu,