Re: [PATCH 1/2] KVM: x86: fix APIC page invalidation

From: çéæ
Date: Wed Dec 06 2017 - 04:51:05 EST


2017-12-06 3:32 GMT+01:00 Wanpeng Li <kernellwp@xxxxxxxxx>:
> 2017-12-01 2:05 GMT+08:00 Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>:
>> Implementation of the unpinned APIC page didn't update the VMCS address
>> cache when invalidation was done through range mmu notifiers.
>> This became a problem when the page notifier was removed.
>>
>> Re-introduce the arch-specific helper and call it from ...range_start.
>>
>> Fixes: 38b9917350cb ("kvm: vmx: Implement set_apic_access_page_addr")
>> Fixes: 369ea8242c0f ("mm/rmap: update to new mmu_notifier semantic v2")
>> Signed-off-by: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
So the patch should be backport to v3.18+?

Thanks,
Jack
>
> Tested-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
>
> I observe the windows 2016 guest hang during boot on a heavy memory
> overcommit host, and this commit fixes it.
>
> Regards,
> Wanpeng Li
>
>> ---
>> arch/x86/include/asm/kvm_host.h | 3 +++
>> arch/x86/kvm/x86.c | 14 ++++++++++++++
>> virt/kvm/kvm_main.c | 8 ++++++++
>> 3 files changed, 25 insertions(+)
>>
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index 977de5fb968b..c16c3f924863 100644
>> --- a/arch/x86/include/asm/kvm_host.h
>> +++ b/arch/x86/include/asm/kvm_host.h
>> @@ -1435,4 +1435,7 @@ static inline int kvm_cpu_get_apicid(int mps_cpu)
>> #define put_smstate(type, buf, offset, val) \
>> *(type *)((buf) + (offset) - 0x7e00) = val
>>
>> +void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,
>> + unsigned long start, unsigned long end);
>> +
>> #endif /* _ASM_X86_KVM_HOST_H */
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index eee8e7faf1af..a219974cdb89 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -6778,6 +6778,20 @@ static void kvm_vcpu_flush_tlb(struct kvm_vcpu *vcpu)
>> kvm_x86_ops->tlb_flush(vcpu);
>> }
>>
>> +void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,
>> + unsigned long start, unsigned long end)
>> +{
>> + unsigned long apic_address;
>> +
>> + /*
>> + * The physical address of apic access page is stored in the VMCS.
>> + * Update it when it becomes invalid.
>> + */
>> + apic_address = gfn_to_hva(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT);
>> + if (start <= apic_address && apic_address < end)
>> + kvm_make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD);
>> +}
>> +
>> void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
>> {
>> struct page *page = NULL;
>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>> index c01cff064ec5..b7f4689e373f 100644
>> --- a/virt/kvm/kvm_main.c
>> +++ b/virt/kvm/kvm_main.c
>> @@ -135,6 +135,11 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm);
>> static unsigned long long kvm_createvm_count;
>> static unsigned long long kvm_active_vms;
>>
>> +__weak void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,
>> + unsigned long start, unsigned long end)
>> +{
>> +}
>> +
>> bool kvm_is_reserved_pfn(kvm_pfn_t pfn)
>> {
>> if (pfn_valid(pfn))
>> @@ -360,6 +365,9 @@ static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
>> kvm_flush_remote_tlbs(kvm);
>>
>> spin_unlock(&kvm->mmu_lock);
>> +
>> + kvm_arch_mmu_notifier_invalidate_range(kvm, start, end);
>> +
>> srcu_read_unlock(&kvm->srcu, idx);
>> }
>>
>> --
>> 2.14.2
>>
>> --
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