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Commit c24ae0dc authored by Tang Chen's avatar Tang Chen Committed by Paolo Bonzini
Browse files

kvm: x86: Unpin and remove kvm_arch->apic_access_page 



In order to make the APIC access page migratable, stop pinning it in
memory.

And because the APIC access page is not pinned in memory, we can
remove kvm_arch->apic_access_page.  When we need to write its
physical address into vmcs, we use gfn_to_page() to get its page
struct, which is needed to call page_to_phys(); the page is then
immediately unpinned.

Suggested-by: default avatarGleb Natapov <gleb@kernel.org>
Signed-off-by: default avatarTang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 38b99173

arch/x86/include/asm/kvm_host.h

+1 −1
Original line number Diff line number Diff line
@@ -574,7 +574,7 @@ struct kvm_arch { 
	struct kvm_apic_map *apic_map;



	unsigned int tss_addr;

	struct page *apic_access_page;

	bool apic_access_page_done;



	gpa_t wall_clock;

arch/x86/kvm/vmx.c

+7 −2
Original line number Diff line number Diff line
@@ -4033,7 +4033,7 @@ static int alloc_apic_access_page(struct kvm *kvm) 
	int r = 0;



	mutex_lock(&kvm->slots_lock);

	if (kvm->arch.apic_access_page)

	if (kvm->arch.apic_access_page_done)

		goto out;

	kvm_userspace_mem.slot = APIC_ACCESS_PAGE_PRIVATE_MEMSLOT;

	kvm_userspace_mem.flags = 0;
@@ -4049,7 +4049,12 @@ static int alloc_apic_access_page(struct kvm *kvm) 
		goto out;

	}



	kvm->arch.apic_access_page = page;

	/*

	 * Do not pin the page in memory, so that memory hot-unplug

	 * is able to migrate it.

	 */

	put_page(page);

	kvm->arch.apic_access_page_done = true;

out:

	mutex_unlock(&kvm->slots_lock);

	return r;

arch/x86/kvm/x86.c

+16 −6
Original line number Diff line number Diff line
@@ -6028,19 +6028,31 @@ static void kvm_vcpu_flush_tlb(struct kvm_vcpu *vcpu) 


void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)

{

	struct page *page = NULL;



	if (!kvm_x86_ops->set_apic_access_page_addr)

		return;



	vcpu->kvm->arch.apic_access_page = gfn_to_page(vcpu->kvm,

			APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT);

	kvm_x86_ops->set_apic_access_page_addr(vcpu,

			page_to_phys(vcpu->kvm->arch.apic_access_page));

	page = gfn_to_page(vcpu->kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT);

	kvm_x86_ops->set_apic_access_page_addr(vcpu, page_to_phys(page));



	/*

	 * Do not pin apic access page in memory, the MMU notifier

	 * will call us again if it is migrated or swapped out.

	 */

	put_page(page);

}

EXPORT_SYMBOL_GPL(kvm_vcpu_reload_apic_access_page);



void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,

					   unsigned long address)

{

	/*

	 * The physical address of apic access page is stored in the VMCS.

	 * Update it when it becomes invalid.

	 */

	if (address == gfn_to_hva(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT))

		kvm_make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD);

}



/*
@@ -7297,8 +7309,6 @@ void kvm_arch_destroy_vm(struct kvm *kvm) 
	kfree(kvm->arch.vpic);

	kfree(kvm->arch.vioapic);

	kvm_free_vcpus(kvm);

	if (kvm->arch.apic_access_page)

		put_page(kvm->arch.apic_access_page);

	kfree(rcu_dereference_check(kvm->arch.apic_map, 1));

}