kvm: x86: Add request bit to reload APIC access page address

Currently, the APIC access page is pinned by KVM for the entire life
of the guest.  We want to make it migratable in order to make memory
hot-unplug available for machines that run KVM.

This patch prepares to handle this in generic code, through a new
request bit (that will be set by the MMU notifier) and a new hook
that is called whenever the request bit is processed.

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 142569e6f8f9..c1412f5d93db 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6026,6 +6026,18 @@ static void kvm_vcpu_flush_tlb(struct kvm_vcpu *vcpu)
         kvm_x86_ops->tlb_flush(vcpu);
 }
 
+void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
+{
+        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));
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_reload_apic_access_page);
+
 void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
                                            unsigned long address)
 {
@@ -6091,6 +6103,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
                         kvm_deliver_pmi(vcpu);
                 if (kvm_check_request(KVM_REQ_SCAN_IOAPIC, vcpu))
                         vcpu_scan_ioapic(vcpu);
+                if (kvm_check_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu))
+                        kvm_vcpu_reload_apic_access_page(vcpu);
         }
 
         if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) {