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From: maobibo <maobibo@loongson.cn>
To: Peter Xu <peterx@redhat.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	linux-mips@vger.kernel.org,
	Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH RFC 4/4] KVM: MIPS: Define arch-specific kvm_flush_remote_tlbs()
Date: Thu, 19 Mar 2020 10:21:09 +0800
Message-ID: <a78041a0-a987-5456-ed3f-44eb1a6022a7@loongson.cn> (raw)
In-Reply-To: <20200318152837.GB26585@xz-x1>



On 03/18/2020 11:28 PM, Peter Xu wrote:
> On Wed, Mar 18, 2020 at 11:03:13AM +0800, maobibo wrote:
>>
>>
>> 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@redhat.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,
>
> Hi, Bibo,
>
>>
>> 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
>
> I'm not familiar with MIPS either, however... I would start to suspect
> MIPS could be problematic with MMU notifiers when cpu_has_guestid is
> not set.  If that's the case, then this series might instead fix it.

yeap, from my viewpoint this series actually fix it when cpu_has_guestid 
is not set, previous kvm_flush_remote_tlbs function do nothing actually 
for MIPS VZ machine without cpu_has_guestid flag.

>
> Thanks,
>


  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-07 22:35 [PATCH RFC 0/4] KVM: MIPS: Provide " Peter Xu
2020-02-07 22:35 ` [PATCH RFC 1/4] KVM: Provide kvm_flush_remote_tlbs_common() Peter Xu
2020-02-12 13:33   ` Paolo Bonzini
2020-02-07 22:35 ` [PATCH RFC 2/4] KVM: MIPS: Drop flush_shadow_memslot() callback Peter Xu
2020-02-07 22:35 ` [PATCH RFC 3/4] KVM: MIPS: Replace all the kvm_flush_remote_tlbs() references Peter Xu
2020-02-07 22:35 ` [PATCH RFC 4/4] KVM: MIPS: Define arch-specific kvm_flush_remote_tlbs() Peter Xu
2020-03-18  3:03   ` maobibo
2020-03-18 15:28     ` Peter Xu
2020-03-19  2:21       ` maobibo [this message]
2020-02-07 23:00 ` [PATCH RFC 0/4] KVM: MIPS: Provide " Peter Xu
2020-02-12 12:25 ` Paolo Bonzini
2020-02-12 16:30   ` Paul Burton
2020-02-12 16:40     ` Paolo Bonzini
2020-02-12 19:02       ` Philippe Mathieu-Daudé
2020-03-11 18:32   ` Peter Xu
2020-03-17 13:33     ` Paolo Bonzini
2020-03-17 14:18       ` Peter Xu

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