| Message ID | 1409134661-27916-3-git-send-email-tangchen@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Aug 27, 2014 at 06:17:37PM +0800, Tang Chen wrote: > kvm_arch->ept_identity_pagetable holds the ept identity pagetable page. But > it is never used to refer to the page at all. > > In vcpu initialization, it indicates two things: > 1. indicates if ept page is allocated > 2. indicates if a memory slot for identity page is initialized > > Actually, kvm_arch->ept_identity_pagetable_done is enough to tell if the ept > identity pagetable is initialized. So we can remove ept_identity_pagetable. > > NOTE: In the original code, ept identity pagetable page is pinned in memroy. > As a result, it cannot be migrated/hot-removed. After this patch, since > kvm_arch->ept_identity_pagetable is removed, ept identity pagetable page > is no longer pinned in memory. And it can be migrated/hot-removed. Reviewed-by: Gleb Natapov <gleb@kernel.org> > > Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com> > --- > arch/x86/include/asm/kvm_host.h | 1 - > arch/x86/kvm/vmx.c | 50 ++++++++++++++++++++--------------------- > arch/x86/kvm/x86.c | 2 -- > 3 files changed, 25 insertions(+), 28 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 7c492ed..35171c7 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -580,7 +580,6 @@ struct kvm_arch { > > gpa_t wall_clock; > > - struct page *ept_identity_pagetable; > bool ept_identity_pagetable_done; > gpa_t ept_identity_map_addr; > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 4b80ead..953d529 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -743,6 +743,7 @@ static u32 vmx_segment_access_rights(struct kvm_segment *var); > static void vmx_sync_pir_to_irr_dummy(struct kvm_vcpu *vcpu); > static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx); > static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx); > +static int alloc_identity_pagetable(struct kvm *kvm); > > static DEFINE_PER_CPU(struct vmcs *, vmxarea); > static DEFINE_PER_CPU(struct vmcs *, current_vmcs); > @@ -3938,21 +3939,27 @@ out: > > static int init_rmode_identity_map(struct kvm *kvm) > { > - int i, idx, r, ret; > + int i, idx, r, ret = 0; > pfn_t identity_map_pfn; > u32 tmp; > > if (!enable_ept) > return 1; > - if (unlikely(!kvm->arch.ept_identity_pagetable)) { > - printk(KERN_ERR "EPT: identity-mapping pagetable " > - "haven't been allocated!\n"); > - return 0; > + > + /* Protect kvm->arch.ept_identity_pagetable_done. */ > + mutex_lock(&kvm->slots_lock); > + > + if (likely(kvm->arch.ept_identity_pagetable_done)) { > + ret = 1; > + goto out2; > } > - if (likely(kvm->arch.ept_identity_pagetable_done)) > - return 1; > - ret = 0; > + > identity_map_pfn = kvm->arch.ept_identity_map_addr >> PAGE_SHIFT; > + > + r = alloc_identity_pagetable(kvm); > + if (r) > + goto out2; > + > idx = srcu_read_lock(&kvm->srcu); > r = kvm_clear_guest_page(kvm, identity_map_pfn, 0, PAGE_SIZE); > if (r < 0) > @@ -3970,6 +3977,9 @@ static int init_rmode_identity_map(struct kvm *kvm) > ret = 1; > out: > srcu_read_unlock(&kvm->srcu, idx); > + > +out2: > + mutex_unlock(&kvm->slots_lock); > return ret; > } > > @@ -4019,31 +4029,23 @@ out: > > static int alloc_identity_pagetable(struct kvm *kvm) > { > - struct page *page; > + /* > + * In init_rmode_identity_map(), kvm->arch.ept_identity_pagetable_done > + * is checked before calling this function and set to true after the > + * calling. The access to kvm->arch.ept_identity_pagetable_done should > + * be protected by kvm->slots_lock. > + */ > + > struct kvm_userspace_memory_region kvm_userspace_mem; > int r = 0; > > - mutex_lock(&kvm->slots_lock); > - if (kvm->arch.ept_identity_pagetable) > - goto out; > kvm_userspace_mem.slot = IDENTITY_PAGETABLE_PRIVATE_MEMSLOT; > kvm_userspace_mem.flags = 0; > kvm_userspace_mem.guest_phys_addr = > kvm->arch.ept_identity_map_addr; > kvm_userspace_mem.memory_size = PAGE_SIZE; > r = __kvm_set_memory_region(kvm, &kvm_userspace_mem); > - if (r) > - goto out; > > - page = gfn_to_page(kvm, kvm->arch.ept_identity_map_addr >> PAGE_SHIFT); > - if (is_error_page(page)) { > - r = -EFAULT; > - goto out; > - } > - > - kvm->arch.ept_identity_pagetable = page; > -out: > - mutex_unlock(&kvm->slots_lock); > return r; > } > > @@ -7643,8 +7645,6 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id) > kvm->arch.ept_identity_map_addr = > VMX_EPT_IDENTITY_PAGETABLE_ADDR; > err = -ENOMEM; > - if (alloc_identity_pagetable(kvm) != 0) > - goto free_vmcs; > if (!init_rmode_identity_map(kvm)) > goto free_vmcs; > } > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 8f1e22d..e05bd58 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -7239,8 +7239,6 @@ void kvm_arch_destroy_vm(struct kvm *kvm) > kvm_free_vcpus(kvm); > if (kvm->arch.apic_access_page) > put_page(kvm->arch.apic_access_page); > - if (kvm->arch.ept_identity_pagetable) > - put_page(kvm->arch.ept_identity_pagetable); > kfree(rcu_dereference_check(kvm->arch.apic_map, 1)); > } > > -- > 1.8.3.1 > -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 7c492ed..35171c7 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -580,7 +580,6 @@ struct kvm_arch { gpa_t wall_clock; - struct page *ept_identity_pagetable; bool ept_identity_pagetable_done; gpa_t ept_identity_map_addr; diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 4b80ead..953d529 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -743,6 +743,7 @@ static u32 vmx_segment_access_rights(struct kvm_segment *var); static void vmx_sync_pir_to_irr_dummy(struct kvm_vcpu *vcpu); static void copy_vmcs12_to_shadow(struct vcpu_vmx *vmx); static void copy_shadow_to_vmcs12(struct vcpu_vmx *vmx); +static int alloc_identity_pagetable(struct kvm *kvm); static DEFINE_PER_CPU(struct vmcs *, vmxarea); static DEFINE_PER_CPU(struct vmcs *, current_vmcs); @@ -3938,21 +3939,27 @@ out: static int init_rmode_identity_map(struct kvm *kvm) { - int i, idx, r, ret; + int i, idx, r, ret = 0; pfn_t identity_map_pfn; u32 tmp; if (!enable_ept) return 1; - if (unlikely(!kvm->arch.ept_identity_pagetable)) { - printk(KERN_ERR "EPT: identity-mapping pagetable " - "haven't been allocated!\n"); - return 0; + + /* Protect kvm->arch.ept_identity_pagetable_done. */ + mutex_lock(&kvm->slots_lock); + + if (likely(kvm->arch.ept_identity_pagetable_done)) { + ret = 1; + goto out2; } - if (likely(kvm->arch.ept_identity_pagetable_done)) - return 1; - ret = 0; + identity_map_pfn = kvm->arch.ept_identity_map_addr >> PAGE_SHIFT; + + r = alloc_identity_pagetable(kvm); + if (r) + goto out2; + idx = srcu_read_lock(&kvm->srcu); r = kvm_clear_guest_page(kvm, identity_map_pfn, 0, PAGE_SIZE); if (r < 0) @@ -3970,6 +3977,9 @@ static int init_rmode_identity_map(struct kvm *kvm) ret = 1; out: srcu_read_unlock(&kvm->srcu, idx); + +out2: + mutex_unlock(&kvm->slots_lock); return ret; } @@ -4019,31 +4029,23 @@ out: static int alloc_identity_pagetable(struct kvm *kvm) { - struct page *page; + /* + * In init_rmode_identity_map(), kvm->arch.ept_identity_pagetable_done + * is checked before calling this function and set to true after the + * calling. The access to kvm->arch.ept_identity_pagetable_done should + * be protected by kvm->slots_lock. + */ + struct kvm_userspace_memory_region kvm_userspace_mem; int r = 0; - mutex_lock(&kvm->slots_lock); - if (kvm->arch.ept_identity_pagetable) - goto out; kvm_userspace_mem.slot = IDENTITY_PAGETABLE_PRIVATE_MEMSLOT; kvm_userspace_mem.flags = 0; kvm_userspace_mem.guest_phys_addr = kvm->arch.ept_identity_map_addr; kvm_userspace_mem.memory_size = PAGE_SIZE; r = __kvm_set_memory_region(kvm, &kvm_userspace_mem); - if (r) - goto out; - page = gfn_to_page(kvm, kvm->arch.ept_identity_map_addr >> PAGE_SHIFT); - if (is_error_page(page)) { - r = -EFAULT; - goto out; - } - - kvm->arch.ept_identity_pagetable = page; -out: - mutex_unlock(&kvm->slots_lock); return r; } @@ -7643,8 +7645,6 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id) kvm->arch.ept_identity_map_addr = VMX_EPT_IDENTITY_PAGETABLE_ADDR; err = -ENOMEM; - if (alloc_identity_pagetable(kvm) != 0) - goto free_vmcs; if (!init_rmode_identity_map(kvm)) goto free_vmcs; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8f1e22d..e05bd58 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7239,8 +7239,6 @@ void kvm_arch_destroy_vm(struct kvm *kvm) kvm_free_vcpus(kvm); if (kvm->arch.apic_access_page) put_page(kvm->arch.apic_access_page); - if (kvm->arch.ept_identity_pagetable) - put_page(kvm->arch.ept_identity_pagetable); kfree(rcu_dereference_check(kvm->arch.apic_map, 1)); }
kvm_arch->ept_identity_pagetable holds the ept identity pagetable page. But it is never used to refer to the page at all. In vcpu initialization, it indicates two things: 1. indicates if ept page is allocated 2. indicates if a memory slot for identity page is initialized Actually, kvm_arch->ept_identity_pagetable_done is enough to tell if the ept identity pagetable is initialized. So we can remove ept_identity_pagetable. NOTE: In the original code, ept identity pagetable page is pinned in memroy. As a result, it cannot be migrated/hot-removed. After this patch, since kvm_arch->ept_identity_pagetable is removed, ept identity pagetable page is no longer pinned in memory. And it can be migrated/hot-removed. Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com> --- arch/x86/include/asm/kvm_host.h | 1 - arch/x86/kvm/vmx.c | 50 ++++++++++++++++++++--------------------- arch/x86/kvm/x86.c | 2 -- 3 files changed, 25 insertions(+), 28 deletions(-)