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>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 022c356e0fed872d732f75bf00b78c900a266615..60f9d73c6282108b1b4d42ab84d02d6d15192109 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -736,6 +736,7 @@ struct kvm_x86_ops {
        void (*hwapic_isr_update)(struct kvm *kvm, int isr);
        void (*load_eoi_exitmap)(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap);
        void (*set_virtual_x2apic_mode)(struct kvm_vcpu *vcpu, bool set);
+       void (*set_apic_access_page_addr)(struct kvm_vcpu *vcpu, hpa_t hpa);
        void (*deliver_posted_interrupt)(struct kvm_vcpu *vcpu, int vector);
        void (*sync_pir_to_irr)(struct kvm_vcpu *vcpu);
        int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
@@ -1044,6 +1045,7 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu);
 int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu);
 int kvm_cpu_get_interrupt(struct kvm_vcpu *v);
 void kvm_vcpu_reset(struct kvm_vcpu *vcpu);
+void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu);
 void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
                                           unsigned long address);
 

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 142569e6f8f94522528b888830f42b8aff7cb612..c1412f5d93dbd36b7ec194d77fd8ccd2e6d31f8e 100644 (file)
--- 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) {

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 12c591fc2571c1ee112896f6fa1eba9cdf7a04c6..d594f9f34429d95ffc7a8ba785f13c6366d367b0 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -136,6 +136,7 @@ static inline bool is_error_page(struct page *page)
 #define KVM_REQ_GLOBAL_CLOCK_UPDATE 22
 #define KVM_REQ_ENABLE_IBS        23
 #define KVM_REQ_DISABLE_IBS       24
+#define KVM_REQ_APIC_PAGE_RELOAD  25
 
 #define KVM_USERSPACE_IRQ_SOURCE_ID            0
 #define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID       1