2022-06-06 04:58:06

by Lai Jiangshan

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

From: Lai Jiangshan <[email protected]>

Parents added into the struct kvm_mmu_pages are never used.

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

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,
--
2.19.1.6.gb485710b

2022-07-19 21:05:59

by Sean Christopherson

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

On Sun, Jun 05, 2022, Lai Jiangshan wrote:
> From: Lai Jiangshan <[email protected]>
>
> 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.