From: David Matlack <dmatlack@google.com>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: Sean Christopherson <seanjc@google.com>,
Anish Moorthy <amoorthy@google.com>,
maz@kernel.org, kvm@vger.kernel.org, kvmarm@lists.linux.dev,
robert.hoo.linux@gmail.com, jthoughton@google.com,
axelrasmussen@google.com, peterx@redhat.com,
nadav.amit@gmail.com, isaku.yamahata@gmail.com,
kconsul@linux.vnet.ibm.com
Subject: Re: [PATCH v7 06/14] KVM: Add memslot flag to let userspace force an exit on missing hva mappings
Date: Mon, 11 Mar 2024 09:20:48 -0700 [thread overview]
Message-ID: <CALzav=cMrt8jhCKZSJL+76L=PUZLBH7D=Uo-5Cd1vBOoEja0Nw@mail.gmail.com> (raw)
In-Reply-To: <Ze6Md/RF8Lbg38Rf@thinky-boi>
On Sun, Mar 10, 2024 at 9:46 PM Oliver Upton <oliver.upton@linux.dev> wrote:
> > >
> > > 2. What is your best guess as to when KVM userfault patches will be available,
> > > even if only in RFC form?
> >
> > We're aiming for the end of April for RFC with KVM/ARM support.
>
> Just to make sure everyone is read in on what this entails -- is this
> the implementation that only worries about vCPUs touching non-present
> memory, leaving the question of other UAPIs that consume guest memory
> (e.g. GIC/ITS table save/restore) up for further discussion?
Yes. The initial version will only support returning to userspace on
invalid vCPU accesses with KVM_EXIT_MEMORY_FAULT. Non-vCPU accesses to
invalid pages (e.g. GIC/ITS table save/restore) will trigger an error
return from __gfn_to_hva_many() (which will cause the corresponding
ioctl to fail). It will be userspace's responsibility to clear the
invalid attribute before invoking those ioctls.
For x86 we may need an blocking kernel-to-userspace notification
mechanism for code paths in the emulator, but we'd like to investigate
and discuss if there are any other cleaner alternatives before going
too far down that route.
next prev parent reply other threads:[~2024-03-11 16:21 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-15 23:53 [PATCH v7 00/14] Improve KVM + userfaultfd performance via KVM_EXIT_MEMORY_FAULTs on stage-2 faults Anish Moorthy
2024-02-15 23:53 ` [PATCH v7 01/14] KVM: Clarify meaning of hva_to_pfn()'s 'atomic' parameter Anish Moorthy
2024-02-15 23:53 ` [PATCH v7 02/14] KVM: Add function comments for __kvm_read/write_guest_page() Anish Moorthy
2024-02-15 23:53 ` [PATCH v7 03/14] KVM: Documentation: Make note of the KVM_MEM_GUEST_MEMFD memslot flag Anish Moorthy
2024-04-09 22:47 ` Sean Christopherson
2024-02-15 23:53 ` [PATCH v7 04/14] KVM: Simplify error handling in __gfn_to_pfn_memslot() Anish Moorthy
2024-04-09 22:44 ` Sean Christopherson
2024-02-15 23:53 ` [PATCH v7 05/14] KVM: Define and communicate KVM_EXIT_MEMORY_FAULT RWX flags to userspace Anish Moorthy
2024-02-15 23:53 ` [PATCH v7 06/14] KVM: Add memslot flag to let userspace force an exit on missing hva mappings Anish Moorthy
2024-03-08 22:07 ` Sean Christopherson
2024-03-09 0:46 ` David Matlack
2024-03-11 4:45 ` Oliver Upton
2024-03-11 16:20 ` David Matlack [this message]
2024-03-11 16:36 ` Sean Christopherson
2024-03-11 17:08 ` Anish Moorthy
2024-03-11 21:21 ` Oliver Upton
2024-02-15 23:53 ` [PATCH v7 07/14] KVM: x86: Enable KVM_CAP_EXIT_ON_MISSING and annotate EFAULTs from stage-2 fault handler Anish Moorthy
2024-02-15 23:53 ` [PATCH v7 08/14] KVM: arm64: Enable KVM_CAP_MEMORY_FAULT_INFO and annotate fault in the " Anish Moorthy
2024-03-04 20:00 ` Oliver Upton
2024-03-04 20:10 ` Oliver Upton
2024-03-04 20:32 ` Sean Christopherson
2024-03-04 21:03 ` Oliver Upton
2024-03-04 22:49 ` Sean Christopherson
2024-03-05 1:01 ` Oliver Upton
2024-03-05 15:39 ` Sean Christopherson
2024-02-15 23:54 ` [PATCH v7 09/14] KVM: arm64: Implement and advertise KVM_CAP_EXIT_ON_MISSING Anish Moorthy
2024-02-15 23:54 ` [PATCH v7 10/14] KVM: selftests: Report per-vcpu demand paging rate from demand paging test Anish Moorthy
2024-04-09 22:49 ` Sean Christopherson
2024-02-15 23:54 ` [PATCH v7 11/14] KVM: selftests: Allow many vCPUs and reader threads per UFFD in " Anish Moorthy
2024-04-09 22:58 ` Sean Christopherson
2024-02-15 23:54 ` [PATCH v7 12/14] KVM: selftests: Use EPOLL in userfaultfd_util reader threads and signal errors via TEST_ASSERT Anish Moorthy
2024-02-15 23:54 ` [PATCH v7 13/14] KVM: selftests: Add memslot_flags parameter to memstress_create_vm() Anish Moorthy
2024-02-15 23:54 ` [PATCH v7 14/14] KVM: selftests: Handle memory fault exits in demand_paging_test Anish Moorthy
2024-02-16 7:36 ` [PATCH v7 00/14] Improve KVM + userfaultfd performance via KVM_EXIT_MEMORY_FAULTs on stage-2 faults Gupta, Pankaj
2024-02-16 20:00 ` Anish Moorthy
2024-02-16 23:40 ` Axel Rasmussen
2024-02-21 7:35 ` Gupta, Pankaj
2024-04-10 0:19 ` Sean Christopherson
2024-05-07 17:38 ` Anish Moorthy
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