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From: Sean Christopherson <seanjc@google.com>
To: Anish Moorthy <amoorthy@google.com>
Cc: oliver.upton@linux.dev, kvm@vger.kernel.org,
	kvmarm@lists.linux.dev, pbonzini@redhat.com, maz@kernel.org,
	robert.hoo.linux@gmail.com, jthoughton@google.com,
	bgardon@google.com, dmatlack@google.com, ricarkol@google.com,
	axelrasmussen@google.com, peterx@redhat.com,
	nadav.amit@gmail.com, isaku.yamahata@gmail.com
Subject: Re: [PATCH v4 01/16] KVM: Allow hva_pfn_fast() to resolve read-only faults.
Date: Thu, 10 Aug 2023 16:48:14 -0700	[thread overview]
Message-ID: <ZNV3Pnqczf6PrNrs@google.com> (raw)
In-Reply-To: <CAF7b7mqczaqwFhFaoicOtWHGEf50f-14cuCXSPj36eZsuCoGUg@mail.gmail.com>

On Thu, Aug 10, 2023, Anish Moorthy wrote:
> I figured I'd start double checking my documentation changes before
> sending out the next version, since those have been a persistent
> issue. So, here's what I've currently got for the commit message here
> 
> > hva_to_pfn_fast() currently just fails for read faults where
> > establishing writable mappings is forbidden, which is unnecessary.
> > Instead, try getting the page without passing FOLL_WRITE. This allows
> > the aforementioned faults to (potentially) be resolved without falling
> > back to slow GUP.

Looks good!  One nit, I would drop the "read" part of "read faults".  This behavior
also applies to executable faults.  You captured the key part well (writable mappings
forbidden), so I don't think there's any need to further clarify what types of
faults this applies to.

  reply	other threads:[~2023-08-10 23:48 UTC|newest]

Thread overview: 79+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-02 16:19 [PATCH v4 00/16] Improve scalability of KVM + userfaultfd live migration via annotated memory faults Anish Moorthy
2023-06-02 16:19 ` [PATCH v4 01/16] KVM: Allow hva_pfn_fast() to resolve read-only faults Anish Moorthy
2023-06-14 14:39   ` Sean Christopherson
2023-06-14 16:57     ` Anish Moorthy
2023-08-10 19:54       ` Anish Moorthy
2023-08-10 23:48         ` Sean Christopherson [this message]
2023-06-02 16:19 ` [PATCH v4 02/16] KVM: x86: Set vCPU exit reason to KVM_EXIT_UNKNOWN at the start of KVM_RUN Anish Moorthy
2023-06-02 20:30   ` Isaku Yamahata
2023-06-05 16:41     ` Anish Moorthy
2023-06-02 16:19 ` [PATCH v4 03/16] KVM: Add KVM_CAP_MEMORY_FAULT_INFO Anish Moorthy
2023-06-03 16:58   ` Isaku Yamahata
2023-06-05 16:37     ` Anish Moorthy
2023-06-14 14:55       ` Sean Christopherson
2023-06-05 17:46   ` Anish Moorthy
2023-06-14 17:35   ` Sean Christopherson
2023-06-20 21:13     ` Anish Moorthy
2023-07-07 11:50     ` Kautuk Consul
2023-07-10 15:00       ` Anish Moorthy
2023-07-11  3:54         ` Kautuk Consul
2023-07-11 14:25           ` Sean Christopherson
2023-08-11 22:12     ` Anish Moorthy
2023-08-14 18:01       ` Sean Christopherson
2023-08-15  0:06         ` Anish Moorthy
2023-08-15  0:43           ` Sean Christopherson
2023-08-15 17:01             ` Anish Moorthy
2023-08-16 15:58               ` Sean Christopherson
2023-08-16 21:28                 ` Anish Moorthy
2023-08-17 23:58                   ` Sean Christopherson
2023-08-18 17:32                     ` Anish Moorthy
2023-08-23 22:20                       ` Sean Christopherson
2023-08-23 23:38                         ` Anish Moorthy
2023-08-24 17:24                           ` Sean Christopherson
2023-08-17 22:55     ` Anish Moorthy
2023-07-05  8:21   ` Kautuk Consul
2023-06-02 16:19 ` [PATCH v4 04/16] KVM: Add docstrings to __kvm_write_guest_page() and __kvm_read_guest_page() Anish Moorthy
2023-06-15  2:41   ` Robert Hoo
2023-08-14 22:51     ` Anish Moorthy
2023-06-02 16:19 ` [PATCH v4 05/16] KVM: Annotate -EFAULTs from kvm_vcpu_write_guest_page() Anish Moorthy
2023-06-14 19:10   ` Sean Christopherson
2023-07-06 22:51     ` Anish Moorthy
2023-07-12 14:08       ` Sean Christopherson
2023-06-02 16:19 ` [PATCH v4 06/16] KVM: Annotate -EFAULTs from kvm_vcpu_read_guest_page() Anish Moorthy
2023-06-14 19:22   ` Sean Christopherson
2023-07-07 17:35     ` Anish Moorthy
2023-06-02 16:19 ` [PATCH v4 07/16] KVM: Simplify error handling in __gfn_to_pfn_memslot() Anish Moorthy
2023-06-14 19:26   ` Sean Christopherson
2023-07-07 17:33     ` Anish Moorthy
2023-07-10 17:40       ` Sean Christopherson
2023-06-02 16:19 ` [PATCH v4 08/16] KVM: x86: Annotate -EFAULTs from kvm_handle_error_pfn() Anish Moorthy
2023-06-14 20:03   ` Sean Christopherson
2023-07-07 18:05     ` Anish Moorthy
2023-06-15  2:43   ` Robert Hoo
2023-06-15 14:40     ` Sean Christopherson
2023-06-02 16:19 ` [PATCH v4 09/16] KVM: Introduce KVM_CAP_NOWAIT_ON_FAULT without implementation Anish Moorthy
2023-06-14 20:11   ` Sean Christopherson
2023-07-06 19:04     ` Anish Moorthy
2023-06-14 21:20   ` Sean Christopherson
2023-06-14 21:23     ` Sean Christopherson
2023-08-23 21:17       ` Anish Moorthy
2023-06-15  3:55     ` Wang, Wei W
2023-06-15 14:56       ` Sean Christopherson
2023-06-16 12:08         ` Wang, Wei W
2023-07-07 18:13     ` Anish Moorthy
2023-07-07 20:07       ` Anish Moorthy
2023-07-11 15:29         ` Sean Christopherson
2023-08-25  0:15           ` Anish Moorthy
2023-08-29 22:41             ` Sean Christopherson
2023-08-30 16:21               ` Anish Moorthy
2023-09-07 21:17                 ` Sean Christopherson
2023-06-02 16:19 ` [PATCH v4 10/16] KVM: x86: Implement KVM_CAP_NOWAIT_ON_FAULT Anish Moorthy
2023-06-14 20:25   ` Sean Christopherson
2023-07-07 17:41     ` Anish Moorthy
2023-06-02 16:19 ` [PATCH v4 11/16] KVM: arm64: " Anish Moorthy
2023-06-02 16:19 ` [PATCH v4 12/16] KVM: selftests: Report per-vcpu demand paging rate from demand paging test Anish Moorthy
2023-06-02 16:19 ` [PATCH v4 13/16] KVM: selftests: Allow many vCPUs and reader threads per UFFD in " Anish Moorthy
2023-06-02 16:19 ` [PATCH v4 14/16] KVM: selftests: Use EPOLL in userfaultfd_util reader threads and signal errors via TEST_ASSERT Anish Moorthy
2023-06-02 16:19 ` [PATCH v4 15/16] KVM: selftests: Add memslot_flags parameter to memstress_create_vm() Anish Moorthy
2023-06-02 16:19 ` [PATCH v4 16/16] KVM: selftests: Handle memory fault exits in demand_paging_test Anish Moorthy
2023-06-20  2:44   ` Robert Hoo

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