Re: [PATCH v8 0/8] kvm, mem-hotplug: Do not pin ept identity pagetable and apic access page.

From: Tang Chen
Date: Thu Sep 25 2014 - 04:19:56 EST

Hi Paolo,

I'd like to help to test the patches.
Would you please tell me what is the best way to test this patch-set ?

I think ept page is being used by regular guest.
Is adding "-cpu xxx,-x2apic option" able to make sure guest is using
apic page ?


On 09/24/2014 04:20 PM, Paolo Bonzini wrote:
Il 24/09/2014 09:57, 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.

This patch-set is based on Linux 3.17.0-rc5.

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 v7->v8:
1. Patch 1/9~3/9 were applied to kvm/queue by Paolo Bonzini <pbonzini@xxxxxxxxxx>.
Just resend them, no changes.
2. Removed previous patch 4/9, which added unnecessary hook has_secondary_apic_access().
3. Set kvm_x86_ops->set_apic_access_page_addr to NULL when hardware had no flexpriority
functionality which actually exists only on x86.
4. Moved declaration of kvm_arch_mmu_notifier_invalidate_page() to arch/*/include/asm/kvm_host.h.
5. Removed useless set_apic_access_page_addr() hook for svm.

Tang Chen (8):
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's apic access page in vcpu_enter_guest().
kvm: Rename make_all_cpus_request() to kvm_make_all_cpus_request() and
make it non-static.
kvm, mem-hotplug: Reload L1's apic access page on migration when L2 is
kvm, mem-hotplug: Add arch specific mmu notifier to handle apic access
kvm, mem-hotplug: Unpin and remove kvm_arch->apic_access_page.

arch/arm/include/asm/kvm_host.h | 5 ++
arch/arm64/include/asm/kvm_host.h | 5 ++
arch/ia64/include/asm/kvm_host.h | 7 ++
arch/mips/include/asm/kvm_host.h | 6 ++
arch/powerpc/include/asm/kvm_host.h | 5 ++
arch/s390/include/asm/kvm_host.h | 8 +++
arch/x86/include/asm/kvm_host.h | 7 +-
arch/x86/kvm/svm.c | 3 +-
arch/x86/kvm/vmx.c | 130 ++++++++++++++++++++++++------------
arch/x86/kvm/x86.c | 45 +++++++++++--
include/linux/kvm_host.h | 2 +
virt/kvm/kvm_main.c | 13 ++--
12 files changed, 180 insertions(+), 56 deletions(-)

Thanks for your persistence! The patches look good, I'll test them and
apply to kvm/queue.


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