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

2014-09-16 Thread Tang Chen
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 , 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(-)

-- 
1.8.3.1

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

2014-09-16 Thread Paolo Bonzini
Il 16/09/2014 12:41, Tang Chen ha scritto:
> 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 , 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.

I'll push 1-3 soon to kvm/queue.  I think v7 will be good. :)

Paolo
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