From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Peter Feiner <pfeiner@google.com>,
Jon Cargille <jcargill@google.com>
Subject: [PATCH 1/2] KVM: x86/mmu: Avoid multiple hash lookups in kvm_get_mmu_page()
Date: Tue, 23 Jun 2020 12:40:26 -0700 [thread overview]
Message-ID: <20200623194027.23135-2-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20200623194027.23135-1-sean.j.christopherson@intel.com>
Refactor for_each_valid_sp() to take the list of shadow pages instead of
retrieving it from a gfn to avoid doing the gfn->list hash and lookup
multiple times during kvm_get_mmu_page().
Cc: Peter Feiner <pfeiner@google.com>
Cc: Jon Cargille <jcargill@google.com>
Cc: Jim Mattson <jmattson@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/mmu/mmu.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 3dd0af7e7515..67f8f82e9783 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2258,15 +2258,14 @@ static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,
static void kvm_mmu_commit_zap_page(struct kvm *kvm,
struct list_head *invalid_list);
-
-#define for_each_valid_sp(_kvm, _sp, _gfn) \
- hlist_for_each_entry(_sp, \
- &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)], hash_link) \
+#define for_each_valid_sp(_kvm, _sp, _list) \
+ hlist_for_each_entry(_sp, _list, hash_link) \
if (is_obsolete_sp((_kvm), (_sp))) { \
} else
#define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \
- for_each_valid_sp(_kvm, _sp, _gfn) \
+ for_each_valid_sp(_kvm, _sp, \
+ &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \
if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else
static inline bool is_ept_sp(struct kvm_mmu_page *sp)
@@ -2477,6 +2476,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
unsigned int access)
{
union kvm_mmu_page_role role;
+ struct hlist_head *sp_list;
unsigned quadrant;
struct kvm_mmu_page *sp;
bool need_sync = false;
@@ -2496,7 +2496,9 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
role.quadrant = quadrant;
}
- for_each_valid_sp(vcpu->kvm, sp, gfn) {
+
+ sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
+ for_each_valid_sp(vcpu->kvm, sp, sp_list) {
if (sp->gfn != gfn) {
collisions++;
continue;
@@ -2533,8 +2535,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
sp->gfn = gfn;
sp->role = role;
- hlist_add_head(&sp->hash_link,
- &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]);
+ hlist_add_head(&sp->hash_link, sp_list);
if (!direct) {
/*
* we should do write protection before syncing pages
--
2.26.0
next prev parent reply other threads:[~2020-06-23 19:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 19:40 [PATCH 0/2] KVM: x86/mmu: Optimizations for kvm_get_mmu_page() Sean Christopherson
2020-06-23 19:40 ` Sean Christopherson [this message]
2020-06-23 20:27 ` [PATCH 1/2] KVM: x86/mmu: Avoid multiple hash lookups in kvm_get_mmu_page() Jon Cargille
2020-06-23 19:40 ` [PATCH 2/2] KVM: x86/mmu: Optimize MMU page cache lookup for fully direct MMUs Sean Christopherson
2020-06-23 20:28 ` Jon Cargille
2020-07-03 17:17 ` [PATCH 0/2] KVM: x86/mmu: Optimizations for kvm_get_mmu_page() Paolo Bonzini
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