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From: Jason Gunthorpe <jgg@nvidia.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Alistair Popple <apopple@nvidia.com>,
	Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH 0/3] KVM: x86: Use "standard" mmu_notifier hook for APIC page
Date: Tue, 6 Jun 2023 13:43:32 -0300	[thread overview]
Message-ID: <ZH9iNAPRBESPVmPA@nvidia.com> (raw)
In-Reply-To: <20230602011518.787006-1-seanjc@google.com>

On Thu, Jun 01, 2023 at 06:15:15PM -0700, Sean Christopherson wrote:
> Convert VMX's handling of mmu_notifier invalidations of the APIC-access page
> from invalidate_range() to KVM's standard invalidate_range_{start,end}().
> 
> KVM (ab)uses invalidate_range() to fudge around not stalling vCPUs until
> relevant in-flight invalidations complete.  Abusing invalidate_range() works,
> but it requires one-off code in KVM, sets a bad precedent in KVM, and is
> blocking improvements to mmu_notifier's definition of invalidate_range()
> due to KVM's usage diverging wildly from the original intent of notifying
> IOMMUs of changes to shared page tables.
> 
> Clean up the mess by hooking x86's implementation of kvm_unmap_gfn_range()
> and stalling vCPUs by re-requesting KVM_REQ_APIC_PAGE_RELOAD until the
> invalidation completes.

I don't know much about kvm, but this looks like what I had in mind
and is a good way to use mmu notifiers

Thanks,
Jason

  parent reply	other threads:[~2023-06-06 16:43 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-02  1:15 [PATCH 0/3] KVM: x86: Use "standard" mmu_notifier hook for APIC page Sean Christopherson
2023-06-02  1:15 ` [PATCH 1/3] KVM: VMX: Retry APIC-access page reload if invalidation is in-progress Sean Christopherson
2023-06-06  2:11   ` Alistair Popple
2023-06-06 17:22     ` Sean Christopherson
2023-06-06 17:39       ` Jason Gunthorpe
2023-06-07  7:40   ` yu.c.zhang
2023-06-07 14:30     ` Sean Christopherson
2023-06-07 17:23       ` Yu Zhang
2023-06-07 17:53         ` Sean Christopherson
2023-06-08  7:00           ` Yu Zhang
2023-06-13 19:07             ` Sean Christopherson
2023-06-17  3:45               ` Yu Zhang
2023-06-22 23:02                 ` Sean Christopherson
2023-06-02  1:15 ` [PATCH 2/3] KVM: x86: Use standard mmu_notifier invalidate hooks for APIC access page Sean Christopherson
2023-06-06  2:20   ` Alistair Popple
2023-06-02  1:15 ` [PATCH 3/3] KVM: x86/mmu: Trigger APIC-access page reload iff vendor code cares Sean Christopherson
2023-06-05 10:15 ` [PATCH 0/3] KVM: x86: Use "standard" mmu_notifier hook for APIC page Paolo Bonzini
2023-06-06 16:43 ` Jason Gunthorpe [this message]
2023-06-07  0:55 ` Sean Christopherson

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