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Date: Thu, 04 Nov 2010 18:36:36 +0800
From: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To: Avi Kivity <avi@...hat.com>
CC: Marcelo Tosatti <mtosatti@...hat.com>,
Gleb Natapov <gleb@...hat.com>,
LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: [PATCH 3/3] KVM: MMU: retry #PF for softmmu
Retry #PF for softmmu only when the current vcpu has the same
root shadow page as the time when #PF occurs. it means they
have same paging environment.
Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
---
arch/x86/include/asm/kvm_host.h | 6 ++++++
arch/x86/kvm/mmu.c | 33 ++++++++++++++++++++++++++++++++-
arch/x86/kvm/x86.c | 16 ++++++++++++++--
virt/kvm/async_pf.c | 1 +
4 files changed, 53 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 7f20f2c..b99ef7d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -192,6 +192,8 @@ struct kvm_mmu_page {
struct list_head link;
struct hlist_node hash_link;
+ struct kref apfs_counter;
+
/*
* The following two entries are used to key the shadow page in the
* hash table.
@@ -600,6 +602,7 @@ struct kvm_x86_ops {
struct kvm_arch_async_pf {
u32 token;
gfn_t gfn;
+ struct kvm_mmu_page *root_sp;
};
extern struct kvm_x86_ops *kvm_x86_ops;
@@ -697,6 +700,8 @@ void kvm_inject_nmi(struct kvm_vcpu *vcpu);
int fx_init(struct kvm_vcpu *vcpu);
+struct kvm_mmu_page *get_vcpu_root_sp(struct kvm_vcpu *vcpu, gva_t gva);
+void kvm_mmu_release_apf_sp(struct kvm_mmu_page *sp);
void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu);
void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
const u8 *new, int bytes,
@@ -822,6 +827,7 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu,
struct kvm_async_pf *work);
bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu);
+void kvm_arch_clear_async_pf(struct kvm_async_pf *work);
extern bool kvm_find_async_pf_gfn(struct kvm_vcpu *vcpu, gfn_t gfn);
#endif /* _ASM_X86_KVM_HOST_H */
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f3fad4f..60cc9f9 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -993,6 +993,19 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, int nr)
percpu_counter_add(&kvm_total_used_mmu_pages, nr);
}
+static void free_shadow_page(struct kref *kref)
+{
+ struct kvm_mmu_page *sp;
+
+ sp = container_of(kref, struct kvm_mmu_page, apfs_counter);
+ kmem_cache_free(mmu_page_header_cache, sp);
+}
+
+void kvm_mmu_release_apf_sp(struct kvm_mmu_page *sp)
+{
+ kref_put(&sp->apfs_counter, free_shadow_page);;
+}
+
static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp)
{
ASSERT(is_empty_shadow_page(sp->spt));
@@ -1001,7 +1014,7 @@ static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp)
__free_page(virt_to_page(sp->spt));
if (!sp->role.direct)
__free_page(virt_to_page(sp->gfns));
- kmem_cache_free(mmu_page_header_cache, sp);
+ kvm_mmu_release_apf_sp(sp);
kvm_mod_used_mmu_pages(kvm, -1);
}
@@ -1026,6 +1039,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
sp->multimapped = 0;
sp->parent_pte = parent_pte;
kvm_mod_used_mmu_pages(vcpu->kvm, +1);
+ kref_init(&sp->apfs_counter);
return sp;
}
@@ -2597,11 +2611,28 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
error_code & PFERR_WRITE_MASK, gfn);
}
+struct kvm_mmu_page *get_vcpu_root_sp(struct kvm_vcpu *vcpu, gva_t gva)
+{
+ struct kvm_shadow_walk_iterator iterator;
+ bool ret;
+
+ shadow_walk_init(&iterator, vcpu, gva);
+ ret = shadow_walk_okay(&iterator);
+ WARN_ON(!ret);
+
+ return page_header(__pa(iterator.sptep));
+}
+
static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn)
{
struct kvm_arch_async_pf arch;
+
arch.token = (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id;
arch.gfn = gfn;
+ if (!tdp_enabled) {
+ arch.root_sp = get_vcpu_root_sp(vcpu, gva);
+ kref_get(&arch.root_sp->apfs_counter);
+ }
return kvm_setup_async_pf(vcpu, gva, gfn, &arch);
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index aacc5eb..72d672f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6174,14 +6174,17 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work)
{
int r;
- if (!tdp_enabled || is_error_page(work->page))
+ if (is_error_page(work->page))
return;
r = kvm_mmu_reload(vcpu);
+
if (unlikely(r))
return;
- vcpu->arch.mmu.page_fault(vcpu, work->gva, 0, true);
+ if (tdp_enabled ||
+ get_vcpu_root_sp(vcpu, work->gva) == work->arch.root_sp)
+ vcpu->arch.mmu.page_fault(vcpu, work->gva, 0, true);
}
static inline u32 kvm_async_pf_hash_fn(gfn_t gfn)
@@ -6269,10 +6272,19 @@ void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu,
}
}
+void kvm_arch_clear_async_pf(struct kvm_async_pf *work)
+{
+ if (!tdp_enabled)
+ kvm_mmu_release_apf_sp(work->arch.root_sp);
+}
+
void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
struct kvm_async_pf *work)
{
trace_kvm_async_pf_ready(work->arch.token, work->gva);
+
+ kvm_arch_clear_async_pf(work);
+
if (is_error_page(work->page))
work->arch.token = ~0; /* broadcast wakeup */
else
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index 74268b4..c3d4788 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -101,6 +101,7 @@ void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu)
typeof(*work), queue);
cancel_work_sync(&work->work);
list_del(&work->queue);
+ kvm_arch_clear_async_pf(work);
if (!work->done) /* work was canceled */
kmem_cache_free(async_pf_cache, work);
}
--
1.7.0.4
--
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