[PATCH v6 0/6] kvm, mem-hotplug: Do not pin ept identity pagetable and apic access page.

[Tang Chen <tangchen@cn.fujitsu.com>]

ept identity pagetable and apic access page in kvm are pinned in memory.
As a result, they cannot be migrated/hot-removed.

But actually they don't need to be pinned in memory.

[For ept identity page]
Just do not pin it. When it is migrated, guest will be able to find the
new page in the next ept violation.

[For apic access page]
The hpa of apic access page is stored in VMCS APIC_ACCESS_ADDR pointer.
When apic access page is migrated, we update VMCS APIC_ACCESS_ADDR pointer
for each vcpu in addition.

NOTE: Tested with -cpu xxx,-x2apic option.
      But since nested vm pins some other pages in memory, if user uses nested
      vm, memory hot-remove will not work.

Change log v5 -> v6:
1. Patch 1/6 has been applied by Paolo Bonzini <pbonzini@redhat.com>, just resend it.
2. Simplify comment in alloc_identity_pagetable() and add a BUG_ON() in patch 2/6.
3. Move err initialization forward in patch 3/6.
4. Rename vcpu_reload_apic_access_page() to kvm_vcpu_reload_apic_access_page() and 
   use it instead of kvm_reload_apic_access_page() in nested_vmx_vmexit() in patch 5/6.
5. Reuse kvm_vcpu_reload_apic_access_page() in prepare_vmcs02() and vmx_vcpu_reset() in patch 6/6.
6. Remove original patch 7 since we are not able to handle the situation in nested vm.

Tang Chen (6):
  kvm: Use APIC_DEFAULT_PHYS_BASE macro as the apic access page address.
  kvm: Remove ept_identity_pagetable from struct kvm_arch.
  kvm: Make init_rmode_identity_map() return 0 on success.
  kvm, mem-hotplug: Reload L1' apic access page on migration in
    vcpu_enter_guest().
  kvm, mem-hotplug: Reload L1's apic access page on migration when L2 is
    running.
  kvm, mem-hotplug: Unpin and remove kvm_arch->apic_access_page.

 arch/x86/include/asm/kvm_host.h |  5 ++-
 arch/x86/kvm/svm.c              |  9 +++-
 arch/x86/kvm/vmx.c              | 95 +++++++++++++++++++++++------------------
 arch/x86/kvm/x86.c              | 25 +++++++++--
 include/linux/kvm_host.h        |  2 +
 virt/kvm/kvm_main.c             | 12 ++++++
 6 files changed, 99 insertions(+), 49 deletions(-)

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1.8.3.1