linux-kernel - Re: [PATCH RFC 4/4] KVM: MIPS: Define arch-specific kvm_flush_remote

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Date:   Wed, 18 Mar 2020 11:03:13 +0800
From:   maobibo <maobibo@...ngson.cn>
To:     Peter Xu <peterx@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        linux-mips@...r.kernel.org, Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: Re: [PATCH RFC 4/4] KVM: MIPS: Define arch-specific
 kvm_flush_remote_tlbs()



On 02/08/2020 06:35 AM, Peter Xu wrote:
> Select HAVE_KVM_ARCH_TLB_FLUSH_ALL for MIPS to define its own
> kvm_flush_remote_tlbs().  It's as simple as calling the
> flush_shadow_all(kvm) hook.  Then replace all the flush_shadow_all()
> calls to use this KVM generic API to do TLB flush.
>
> Signed-off-by: Peter Xu <peterx@...hat.com>
> ---
>  arch/mips/kvm/Kconfig |  1 +
>  arch/mips/kvm/mips.c  | 22 ++++++++++------------
>  2 files changed, 11 insertions(+), 12 deletions(-)
>
> diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
> index eac25aef21e0..8a06f660d39e 100644
> --- a/arch/mips/kvm/Kconfig
> +++ b/arch/mips/kvm/Kconfig
> @@ -26,6 +26,7 @@ config KVM
>  	select KVM_MMIO
>  	select MMU_NOTIFIER
>  	select SRCU
> +	select HAVE_KVM_ARCH_TLB_FLUSH_ALL
>  	---help---
>  	  Support for hosting Guest kernels.
>
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index 1d5e7ffda746..518020b466bf 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -194,13 +194,16 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
>  	return 0;
>  }
>
> +void kvm_flush_remote_tlbs(struct kvm *kvm)
> +{
> +	kvm_mips_callbacks->flush_shadow_all(kvm);
> +}
> +
Hi Peter,

Although I do not understand mip VZ fully, however it changes behavior 
of MIPS VZ, since kvm_flush_remote_tlbs is also called in function 
kvm_mmu_notifier_change_pte/kvm_mmu_notifier_invalidate_range_start

regards
bibo, mao

>  void kvm_arch_flush_shadow_all(struct kvm *kvm)
>  {
>  	/* Flush whole GPA */
>  	kvm_mips_flush_gpa_pt(kvm, 0, ~0);
> -
> -	/* Let implementation do the rest */
> -	kvm_mips_callbacks->flush_shadow_all(kvm);
> +	kvm_flush_remote_tlbs(kvm);
>  }
>
>  void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
> @@ -215,8 +218,7 @@ void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
>  	/* Flush slot from GPA */
>  	kvm_mips_flush_gpa_pt(kvm, slot->base_gfn,
>  			      slot->base_gfn + slot->npages - 1);
> -	/* Let implementation do the rest */
> -	kvm_mips_callbacks->flush_shadow_all(kvm);
> +	kvm_flush_remote_tlbs(kvm);
>  	spin_unlock(&kvm->mmu_lock);
>  }
>
> @@ -258,7 +260,7 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
>  					new->base_gfn + new->npages - 1);
>  		/* Let implementation do the rest */
>  		if (needs_flush)
> -			kvm_mips_callbacks->flush_shadow_all(kvm);
> +			kvm_flush_remote_tlbs(kvm);
>  		spin_unlock(&kvm->mmu_lock);
>  	}
>  }
> @@ -1001,9 +1003,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
>  	if (flush) {
>  		slots = kvm_memslots(kvm);
>  		memslot = id_to_memslot(slots, log->slot);
> -
> -		/* Let implementation handle TLB/GVA invalidation */
> -		kvm_mips_callbacks->flush_shadow_all(kvm);
> +		kvm_flush_remote_tlbs(kvm);
>  	}
>
>  	mutex_unlock(&kvm->slots_lock);
> @@ -1024,9 +1024,7 @@ int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm, struct kvm_clear_dirty_log *lo
>  	if (flush) {
>  		slots = kvm_memslots(kvm);
>  		memslot = id_to_memslot(slots, log->slot);
> -
> -		/* Let implementation handle TLB/GVA invalidation */
> -		kvm_mips_callbacks->flush_shadow_all(kvm);
> +		kvm_flush_remote_tlbs(kvm);
>  	}
>
>  	mutex_unlock(&kvm->slots_lock);
>