Re: [PATCH 1/1] kvm, mem-hotplug: Add arch specific mmu notifier to handle apic access migration.

[Paolo Bonzini]

Il 24/09/2014 04:09, Tang Chen ha scritto:
> Hi Paolo, 
> 
> I'm not sure if this patch is following your comment. Please review.
> And all the other comments are followed. If this patch is OK, I'll 
> send v8 soon.
> 
> Thanks.
> 
> We are handling "L1 and L2 share one apic access page" situation when migrating
> apic access page. We should do some handling when migration happens in the
> following situations:
> 
>    1) when L0 is running: Update L1's vmcs in the next L0->L1 entry and L2's
>       vmcs in the next L1->L2 entry.
> 
>    2) when L1 is running: Force a L1->L0 exit, update L1's vmcs in the next
>       L0->L1 entry and L2's vmcs in the next L1->L2 entry.
> 
>    3) when L2 is running: Force a L2->L0 exit, update L2's vmcs in the next
>       L0->L2 entry and L1's vmcs in the next L2->L1 exit.
> 
> This patch force a L1->L0 exit or L2->L0 exit when shared apic access page is
> migrated using mmu notifier. Since apic access page is only used on intel x86,
> this is arch specific code.
> ---
>  arch/arm/include/asm/kvm_host.h     |  6 ++++++
>  arch/arm64/include/asm/kvm_host.h   |  6 ++++++
>  arch/ia64/include/asm/kvm_host.h    |  8 ++++++++
>  arch/mips/include/asm/kvm_host.h    |  7 +++++++
>  arch/powerpc/include/asm/kvm_host.h |  6 ++++++
>  arch/s390/include/asm/kvm_host.h    |  9 +++++++++
>  arch/x86/include/asm/kvm_host.h     |  2 ++
>  arch/x86/kvm/x86.c                  | 11 +++++++++++
>  virt/kvm/kvm_main.c                 |  3 +++
>  9 files changed, 58 insertions(+)
> 
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 6dfb404..79bbf7d 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -182,6 +182,12 @@ static inline int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
>  	return 0;
>  }
>  
> +static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
> +							 unsigned long address)
> +{
> +	return;
> +}
> +
>  struct kvm_vcpu *kvm_arm_get_running_vcpu(void);
>  struct kvm_vcpu __percpu **kvm_get_running_vcpus(void);
>  
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index e10c45a..ee89fad 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -192,6 +192,12 @@ static inline int kvm_test_age_hva(struct kvm *kvm, unsigned long hva)
>  	return 0;
>  }
>  
> +static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
> +							 unsigned long address)
> +{
> +	return;
> +}
> +
>  struct kvm_vcpu *kvm_arm_get_running_vcpu(void);
>  struct kvm_vcpu __percpu **kvm_get_running_vcpus(void);
>  
> diff --git a/arch/ia64/include/asm/kvm_host.h b/arch/ia64/include/asm/kvm_host.h
> index db95f57..326ac55 100644
> --- a/arch/ia64/include/asm/kvm_host.h
> +++ b/arch/ia64/include/asm/kvm_host.h
> @@ -574,6 +574,14 @@ static inline struct kvm_pt_regs *vcpu_regs(struct kvm_vcpu *v)
>  	return (struct kvm_pt_regs *) ((unsigned long) v + KVM_STK_OFFSET) - 1;
>  }
>  
> +#ifdef KVM_ARCH_WANT_MMU_NOTIFIER
> +static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
> +							 unsigned long address)
> +{
> +	return;
> +}
> +#endif /* KVM_ARCH_WANT_MMU_NOTIFIER */
> +
>  typedef int kvm_vmm_entry(void);
>  typedef void kvm_tramp_entry(union context *host, union context *guest);
>  
> diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
> index 7a3fc67..c392705 100644
> --- a/arch/mips/include/asm/kvm_host.h
> +++ b/arch/mips/include/asm/kvm_host.h
> @@ -767,5 +767,12 @@ extern int kvm_mips_trans_mtc0(uint32_t inst, uint32_t *opc,
>  extern void kvm_mips_dump_stats(struct kvm_vcpu *vcpu);
>  extern unsigned long kvm_mips_get_ramsize(struct kvm *kvm);
>  
> +#ifdef KVM_ARCH_WANT_MMU_NOTIFIER
> +static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
> +							 unsigned long address)
> +{
> +	return;
> +}
> +#endif /* KVM_ARCH_WANT_MMU_NOTIFIER */
>  
>  #endif /* __MIPS_KVM_HOST_H__ */
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index 98d9dd5..c16a573 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -61,6 +61,12 @@ extern int kvm_age_hva(struct kvm *kvm, unsigned long hva);
>  extern int kvm_test_age_hva(struct kvm *kvm, unsigned long hva);
>  extern void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);
>  
> +static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
> +							 unsigned long address)
> +{
> +	return;
> +}
> +
>  #define HPTEG_CACHE_NUM			(1 << 15)
>  #define HPTEG_HASH_BITS_PTE		13
>  #define HPTEG_HASH_BITS_PTE_LONG	12
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index 773bef7..693290f 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -450,4 +450,13 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
>  
>  extern int sie64a(struct kvm_s390_sie_block *, u64 *);
>  extern char sie_exit;
> +
> +#ifdef KVM_ARCH_WANT_MMU_NOTIFIER
> +static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
> +							 unsigned long address)
> +{
> +	return;
> +}
> +#endif /* KVM_ARCH_WANT_MMU_NOTIFIER */
> +
>  #endif
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 66480fd..408b944 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1047,6 +1047,8 @@ int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu);
>  int kvm_cpu_get_interrupt(struct kvm_vcpu *v);
>  void kvm_vcpu_reset(struct kvm_vcpu *vcpu);
>  void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu);
> +void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
> +					   unsigned long address);
>  
>  void kvm_define_shared_msr(unsigned index, u32 msr);
>  void kvm_set_shared_msr(unsigned index, u64 val, u64 mask);
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index c064ca6..e042ef6 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6011,6 +6011,17 @@ void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
>  }
>  EXPORT_SYMBOL_GPL(kvm_vcpu_reload_apic_access_page);
>  
> +void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
> +					   unsigned long address)
> +{
> +	/*
> +	 * 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_make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD);
> +}
> +
>  /*
>   * Returns 1 to let __vcpu_run() continue the guest execution loop without
>   * exiting to the userspace.  Otherwise, the value will be returned to the
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 0f8b6f6..5427973d 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -295,6 +295,9 @@ static void kvm_mmu_notifier_invalidate_page(struct mmu_notifier *mn,
>  		kvm_flush_remote_tlbs(kvm);
>  
>  	spin_unlock(&kvm->mmu_lock);
> +
> +	kvm_arch_mmu_notifier_invalidate_page(kvm, address);
> +
>  	srcu_read_unlock(&kvm->srcu, idx);
>  }
>  
> 

Yes, this is it.

Paolo
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