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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: Gleb Natapov <gleb@kernel.org>
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Tang Chen 2014-09-24 15:57:58 +08:00 committed by Paolo Bonzini
parent 38b9917350
commit c24ae0dcd3
3 changed files with 24 additions and 9 deletions
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2
arch/x86/include/asm/kvm_host.h
View File

@ -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;

9
arch/x86/kvm/vmx.c
View File

@ -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;

22
arch/x86/kvm/x86.c
View File

@ -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));
}