[PATCH v2 09/21] KVM: x86/mmu: Separate the memory caches for shadow pages and gfn arrays

Sean Christopherson
2020-06-22T20:09:19Z

Use separate caches for allocating shadow pages versus gfn arrays. This
sets the stage for specifying __GFP_ZERO when allocating shadow pages
without incurring extra cost for gfn arrays.

No functional change intended.

Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/include/asm/kvm_host.h | 3 ++-
arch/x86/kvm/mmu/mmu.c | 15 ++++++++++-----
2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7b6ac8fad9c2..376e1653ac41 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -636,7 +636,8 @@ struct kvm_vcpu_arch {
struct kvm_mmu *walk_mmu;

struct kvm_mmu_memory_cache mmu_pte_list_desc_cache;
- struct kvm_mmu_memory_cache mmu_page_cache;
+ struct kvm_mmu_memory_cache mmu_shadow_page_cache;
+ struct kvm_mmu_memory_cache mmu_gfn_array_cache;
struct kvm_mmu_memory_cache mmu_page_header_cache;

/*
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 451e0365e5dd..d245acece3cd 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1108,8 +1108,12 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
1 + PT64_ROOT_MAX_LEVEL + PTE_PREFETCH_NUM);
if (r)
return r;
- r = mmu_topup_memory_cache(&vcpu->arch.mmu_page_cache,
- 2 * PT64_ROOT_MAX_LEVEL);
+ r = mmu_topup_memory_cache(&vcpu->arch.mmu_shadow_page_cache,
+ PT64_ROOT_MAX_LEVEL);
+ if (r)
+ return r;
+ r = mmu_topup_memory_cache(&vcpu->arch.mmu_gfn_array_cache,
+ PT64_ROOT_MAX_LEVEL);
if (r)
return r;
return mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache,
@@ -1119,7 +1123,8 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
{
mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache);
- mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
+ mmu_free_memory_cache(&vcpu->arch.mmu_shadow_page_cache);
+ mmu_free_memory_cache(&vcpu->arch.mmu_gfn_array_cache);
mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache);
}

@@ -2096,9 +2101,9 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct
struct kvm_mmu_page *sp;

sp = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
- sp->spt = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache);
+ sp->spt = mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
if (!direct)
- sp->gfns = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache);
+ sp->gfns = mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache);
set_page_private(virt_to_page(sp->spt), (unsigned long)sp);

/*
--
2.26.0