linux-kernel - [PATCH v3 0/6] kvm, mem-hotplug: Do not pin ept identity pagetable and apic access page.

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Date:	Wed, 23 Jul 2014 15:42:04 -0400
From:	Tang Chen <tangchen@...fujitsu.com>
To:	<gleb@...nel.org>, <mtosatti@...hat.com>, <nadav.amit@...il.com>,
	<jan.kiszka@....de>
CC:	<kvm@...r.kernel.org>, <laijs@...fujitsu.com>,
	<isimatu.yasuaki@...fujitsu.com>, <guz.fnst@...fujitsu.com>,
	<linux-kernel@...r.kernel.org>, <tangchen@...fujitsu.com>
Subject: [PATCH v3 0/6] kvm, mem-hotplug: Do not pin ept identity pagetable and apic access page.

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: Patch 1~5 are tested with -cpu xxx,-x2apic option, and they work well.
      Patch 6 is not tested yet, not sure if it is right.

Change log v2 -> v3:
1. Remove original [PATCH 3/6] since ept_identity_pagetable has been removed
   in new [PATCH 3/6].
2. In [PATCH 3/6], fix the problem that kvm->slots_lock does not protect 
   kvm->arch.ept_identity_pagetable_done checking.
3. In [PATCH 3/6], drop gfn_to_page() since ept_identity_pagetable has been 
   removed.
4. Add new [PATCH 4/6], remove redundant variable in init_rmode_identity_map(), 
   and make it return 0 on success.
5. In [PATCH 5/6], drop put_page(kvm->arch.apic_access_page) from x86.c .
6. In [PATCH 5/6], update kvm->arch.apic_access_page in vcpu_reload_apic_access_page().
7. Add new [PATCH 6/6], reload apic access page in L2->L1 exit.

Change log v1 -> v2:
1. Add [PATCH 4/5] to remove unnecessary kvm_arch->ept_identity_pagetable.
2. In [PATCH 5/5], only introduce KVM_REQ_APIC_PAGE_RELOAD request.
3. In [PATCH 5/5], add set_apic_access_page_addr() for svm.

Tang Chen (6):
  kvm: Add gfn_to_page_no_pin() to translate gfn to page without
    pinning.
  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: Do not pin apic access page in memory.
  kvm, mem-hotplug: Reload L1's apic access page if it is migrated when
    L2 is running.

 arch/x86/include/asm/kvm_host.h |   3 +-
 arch/x86/kvm/svm.c              |  15 +++++-
 arch/x86/kvm/vmx.c              | 108 +++++++++++++++++++++++++++-------------
 arch/x86/kvm/x86.c              |  22 ++++++--
 include/linux/kvm_host.h        |   3 ++
 virt/kvm/kvm_main.c             |  29 ++++++++++-
 6 files changed, 139 insertions(+), 41 deletions(-)

-- 
1.8.3.1

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