linux-kernel - Re: [PATCH v6 4/6] kvm, mem-hotplug: Reload L1' apic access page on migration in vcpu_enter

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Date:	Tue, 16 Sep 2014 13:24:17 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Tang Chen <tangchen@...fujitsu.com>, 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
Subject: Re: [PATCH v6 4/6] kvm, mem-hotplug: Reload L1' apic access page
 on migration in vcpu_enter_guest().

Il 16/09/2014 12:42, Tang Chen ha scritto:
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 33712fb..0df82c1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -210,6 +210,11 @@ void kvm_make_scan_ioapic_request(struct kvm *kvm)
>  	make_all_cpus_request(kvm, KVM_REQ_SCAN_IOAPIC);
>  }
>  
> +void kvm_reload_apic_access_page(struct kvm *kvm)
> +{
> +	make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD);
> +}
> +
>  int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
>  {
>  	struct page *page;
> @@ -294,6 +299,13 @@ static void kvm_mmu_notifier_invalidate_page(struct mmu_notifier *mn,
>  	if (need_tlb_flush)
>  		kvm_flush_remote_tlbs(kvm);
>  
> +	/*
> +	 * The physical address of apic access page is stored in VMCS.
> +	 * Update it when it becomes invalid.
> +	 */
> +	if (address == gfn_to_hva(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT))
> +		kvm_reload_apic_access_page(kvm);

This cannot be in the generic code.  It is architecture-specific.
Please add a new function kvm_arch_mmu_notifier_invalidate_page, and
call it outside the mmu_lock.

kvm_reload_apic_access_page need not be in virt/kvm/kvm_main.c, either.

Paolo

>  	spin_unlock(&kvm->mmu_lock);
>  	srcu_read_unlock(&kvm->srcu, idx);
>  }

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