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Commit a255d479 authored by Tang Chen's avatar Tang Chen Committed by Paolo Bonzini
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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: default avatarTang Chen <tangchen@cn.fujitsu.com>
Reviewed-by: default avatarGleb Natapov <gleb@kernel.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 80ce1639

arch/x86/include/asm/kvm_host.h

+0 −1
Original line number Diff line number Diff line
@@ -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;

arch/x86/kvm/vmx.c

+22 −25
Original line number Diff line number Diff line
@@ -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 @@ static int init_rmode_tss(struct kvm *kvm) 


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 @@ static int alloc_apic_access_page(struct kvm *kvm) 


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;

	}

arch/x86/kvm/x86.c

+0 −2
Original line number Diff line number Diff line
@@ -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));

}