From a255d4795f83cf3e6a1c7d5ab998392d9413298c Mon Sep 17 00:00:00 2001 From: Tang Chen Date: Tue, 16 Sep 2014 18:41:58 +0800 Subject: [PATCH] kvm: Remove ept_identity_pagetable from struct kvm_arch. 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 Reviewed-by: Gleb Natapov Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 1 - arch/x86/kvm/vmx.c | 47 +++++++++++++++------------------ arch/x86/kvm/x86.c | 2 -- 3 files changed, 22 insertions(+), 28 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 2dbde3b7446c..028df8dc538e 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -578,7 +578,6 @@ 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 5db47db6574b..5de0d7b1d8a9 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -767,6 +767,7 @@ 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); @@ -3962,21 +3963,27 @@ 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) @@ -3994,6 +4001,9 @@ 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; } @@ -4043,31 +4053,20 @@ out: static int alloc_identity_pagetable(struct kvm *kvm) { - struct page *page; + /* Called with kvm->slots_lock held. */ + struct kvm_userspace_memory_region kvm_userspace_mem; int r = 0; - mutex_lock(&kvm->slots_lock); - if (kvm->arch.ept_identity_pagetable) - goto out; + BUG_ON(kvm->arch.ept_identity_pagetable_done); + 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; } @@ -7758,8 +7757,6 @@ 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 68660b31457e..2d7f65daa8d0 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7273,8 +7273,6 @@ 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)); } -- 2.30.2