diff mbox series

[08/12] KVM: X86/MMU: Remove the useless idx from struct kvm_mmu_pages

Message ID 20220605064342.309219-9-jiangshanlai@gmail.com (mailing list archive)
State New, archived
Headers show
Series KVM: X86/MMU: Simpliy mmu_unsync_walk() | expand

Commit Message

Lai Jiangshan June 5, 2022, 6:43 a.m. UTC 
From: Lai Jiangshan <jiangshan.ljs@antgroup.com>

The value is only set but never really used.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
---
 arch/x86/kvm/mmu/mmu.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

Comments

Sean Christopherson July 19, 2022, 8:31 p.m. UTC | #1 
It's arguably not useless, e.g. it's still used for a sanity check.  Not sure
how to word that though.  Maybe?

  KVM: x86/mmu: Drop no-longer-necessary mmu_page_and_offset.idx

On Sun, Jun 05, 2022, Lai Jiangshan wrote:
> From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
> 
> The value is only set but never really used.

Please elaborate on why it's no longer truly used.  Something like:

  Drop mmu_page_and_offset.idx, it's no longer strictly necessary now that
  KVM doesn't recurse up the walk to clear unsync information in parents.
  The field is still used for a sanity check, but that sanity check will
  soon be made obsolete by further simplifying the gathering of unsync
  shadow pages
diff mbox series

Patch

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 65a2f4a2ce25..dc159db46b34 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1745,13 +1745,11 @@  static int nonpaging_sync_page(struct kvm_vcpu *vcpu,
 struct kvm_mmu_pages {
 	struct mmu_page_and_offset {
 		struct kvm_mmu_page *sp;
-		unsigned int idx;
 	} page[KVM_PAGE_ARRAY_NR];
 	unsigned int nr;
 };
 
-static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp,
-			 int idx)
+static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp)
 {
 	int i;
 
@@ -1761,7 +1759,6 @@  static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp,
 				return 0;
 
 	pvec->page[pvec->nr].sp = sp;
-	pvec->page[pvec->nr].idx = idx;
 	pvec->nr++;
 	return (pvec->nr == KVM_PAGE_ARRAY_NR);
 }
@@ -1790,7 +1787,7 @@  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, i))
+			if (mmu_pages_add(pvec, child))
 				return -ENOSPC;
 
 			ret = __mmu_unsync_walk_and_clear(child, pvec);
@@ -1808,7 +1805,7 @@  static int __mmu_unsync_walk_and_clear(struct kvm_mmu_page *sp,
 		clear_unsync_child_bit(sp, i);
 		if (child->unsync) {
 			nr_unsync_leaf++;
-			if (mmu_pages_add(pvec, child, i))
+			if (mmu_pages_add(pvec, child))
 				return -ENOSPC;
 		}
 	}
@@ -1816,8 +1813,6 @@  static int __mmu_unsync_walk_and_clear(struct kvm_mmu_page *sp,
 	return nr_unsync_leaf;
 }
 
-#define INVALID_INDEX (-1)
-
 static int mmu_unsync_walk_and_clear(struct kvm_mmu_page *sp,
 			   struct kvm_mmu_pages *pvec)
 {
@@ -1825,7 +1820,7 @@  static int mmu_unsync_walk_and_clear(struct kvm_mmu_page *sp,
 	if (!sp->unsync_children)
 		return 0;
 
-	mmu_pages_add(pvec, sp, INVALID_INDEX);
+	mmu_pages_add(pvec, sp);
 	return __mmu_unsync_walk_and_clear(sp, pvec);
 }
 
@@ -1926,8 +1921,6 @@  static int mmu_pages_first(struct kvm_mmu_pages *pvec)
 	if (pvec->nr == 0)
 		return 0;
 
-	WARN_ON(pvec->page[0].idx != INVALID_INDEX);
-
 	sp = pvec->page[0].sp;
 	level = sp->role.level;
 	WARN_ON(level == PG_LEVEL_4K);