Just like we removed kvm_arch->apic_access_page, nested_vmx->apic_access_page
becomes useless for the same reason. This patch removes 
nested_vmx->apic_access_page,
and use gfn_to_page() to pin it in memory when we need it, and unpin it after 
then.

Signed-off-by: Tang Chen <tangc...@cn.fujitsu.com>
---
 arch/x86/kvm/vmx.c | 31 +++++++++----------------------
 1 file changed, 9 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 058c373..4aa73cb 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -374,11 +374,6 @@ struct nested_vmx {
        u64 vmcs01_tsc_offset;
        /* L2 must run next, and mustn't decide to exit to L1. */
        bool nested_run_pending;
-       /*
-        * Guest pages referred to in vmcs02 with host-physical pointers, so
-        * we must keep them pinned while L2 runs.
-        */
-       struct page *apic_access_page;
        u64 msr_ia32_feature_control;
 
        struct hrtimer preemption_timer;
@@ -6154,11 +6149,6 @@ static void free_nested(struct vcpu_vmx *vmx)
        nested_release_vmcs12(vmx);
        if (enable_shadow_vmcs)
                free_vmcs(vmx->nested.current_shadow_vmcs);
-       /* Unpin physical memory we referred to in current vmcs02 */
-       if (vmx->nested.apic_access_page) {
-               nested_release_page(vmx->nested.apic_access_page);
-               vmx->nested.apic_access_page = 0;
-       }
 
        nested_free_all_saved_vmcss(vmx);
 }
@@ -7983,28 +7973,31 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, 
struct vmcs12 *vmcs12)
                        exec_control |= vmcs12->secondary_vm_exec_control;
 
                if (exec_control & SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES) {
+                       struct page *page;
                        /*
                         * Translate L1 physical address to host physical
                         * address for vmcs02. Keep the page pinned, so this
                         * physical address remains valid. We keep a reference
                         * to it so we can release it later.
                         */
-                       if (vmx->nested.apic_access_page) /* shouldn't happen */
-                               
nested_release_page(vmx->nested.apic_access_page);
-                       vmx->nested.apic_access_page =
-                               nested_get_page(vcpu, vmcs12->apic_access_addr);
+                       page = nested_get_page(vcpu, vmcs12->apic_access_addr);
                        /*
                         * If translation failed, no matter: This feature asks
                         * to exit when accessing the given address, and if it
                         * can never be accessed, this feature won't do
                         * anything anyway.
                         */
-                       if (!vmx->nested.apic_access_page)
+                       if (!page)
                                exec_control &=
                                  ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
                        else
                                vmcs_write64(APIC_ACCESS_ADDR,
-                                 page_to_phys(vmx->nested.apic_access_page));
+                                            page_to_phys(page));
+                       /*
+                        * Do not pin nested vm's apic access page in memory so
+                        * that memory hotplug process is able to migrate it.
+                        */
+                       put_page(page);
                } else if (vm_need_virtualize_apic_accesses(vmx->vcpu.kvm)) {
                        struct page *page = gfn_to_page(vmx->vcpu.kvm,
                                APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT);
@@ -8807,12 +8800,6 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 
exit_reason,
        /* This is needed for same reason as it was needed in prepare_vmcs02 */
        vmx->host_rsp = 0;
 
-       /* Unpin physical memory we referred to in vmcs02 */
-       if (vmx->nested.apic_access_page) {
-               nested_release_page(vmx->nested.apic_access_page);
-               vmx->nested.apic_access_page = 0;
-       }
-
        /*
         * Do not call kvm_reload_apic_access_page() because we are now
         * running, mmu_notifier will force to reload the page's hpa for L2
-- 
1.8.3.1

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