On Thu, Nov 04, 2010 at 06:36:36PM +0800, Xiao Guangrong wrote: > 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. > Avi had an idea to allocate spte at the fault time, get reference to it and populate it on completion instead of prefaulting. How hard will it be?
> Signed-off-by: Xiao Guangrong <[email protected]> > --- > 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 -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
