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From:   Gavin Shan <gshan@redhat.com>
To:     kvmarm@lists.cs.columbia.edu
Cc:     linux-kernel@vger.kernel.org, eauger@redhat.com, oupton@google.com,
        Jonathan.Cameron@huawei.com, vkuznets@redhat.com, will@kernel.org,
        shannon.zhaosl@gmail.com, james.morse@arm.com,
        mark.rutland@arm.com, maz@kernel.org, pbonzini@redhat.com,
        shan.gavin@gmail.com
Subject: [PATCH v6 00/18] Support SDEI Virtualization
Date:   Sun,  3 Apr 2022 23:38:53 +0800
Message-Id: <20220403153911.12332-1-gshan@redhat.com>
MIME-Version: 1.0
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Precedence: bulk

This series intends to virtualize Software Delegated Exception Interface
(SDEI), which is defined by DEN0054C (v1.1). It allows the hypervisor to
deliver NMI-alike SDEI event to guest and it's needed by Async PF to
deliver page-not-present notification from hypervisor to guest. The code
and the required qemu changes can be found from:

   https://developer.arm.com/documentation/den0054/c
   https://github.com/gwshan/linux    ("kvm/arm64_sdei")
   https://github.com/gwshan/qemu     ("kvm/arm64_sdei")

The design is quite strightforward by following the specification. The
(SDEI) events are classified into the shared and private ones according
to their scope. The shared event is system or VM scoped, but the private
event is vcpu scoped. This implementation doesn't support the shared
event because all the needed events are private. Besides, the migration
isn't supported by implementation and it's something to be supported
in future.

There are several objects (data structures) introduced to help on the
event registration, enablement, disablement, unregistration, reset,
delivery and handling.

  * kvm_sdei_exposed_event
    The event which are defined and exposed by KVM. The event can't
    be registered until it's exposed. Besides, all the information
    in this event can't be changed after it's exposed.
    
  * kvm_sdei_event
    The events are created based on the exposed events. Their states
    are changed when hypercalls are received or they are delivered
    to guest for handling.
    
  * kvm_sdei_vcpu_context
    The vcpu context helps to handle events. The interrupted context
    is saved before the event handler is executed, and restored after
    the event handler is to finish.
    
  * kvm_sdei_vcpu
    Place holder for all objects for one particular VCPU.

The patches are organized as below:

  PATCH[01-02] Preparatory work to extend smccc_get_argx() and refactor
               hypercall routing mechanism
  PATCH[03]    Adds SDEI virtualization infrastructure
  PATCH[04-16] Supports various SDEI hypercalls and event handling
  PATCH[17]    Exposes SDEI capability
  PATCH[18]    Adds SDEI selftest case
  
The previous revisions can be found:

  v5: https://lore.kernel.org/kvmarm/20220322080710.51727-1-gshan@redhat.com/
  v4: https://lore.kernel.org/kvmarm/20210815001352.81927-1-gshan@redhat.com/
  v3: https://lore.kernel.org/kvmarm/20210507083124.43347-1-gshan@redhat.com/
  v2: https://lore.kernel.org/kvmarm/20210209032733.99996-1-gshan@redhat.com/
  v1: https://lore.kernel.org/kvmarm/20200817100531.83045-1-gshan@redhat.com/

Testing
=======
[1] The selftest case included in this series works fine. The default SDEI
    event, whose number is zero, can be registered, enabled, raised. The
    SDEI event handler can be invoked.

    [host]# pwd
    /home/gavin/sandbox/linux.main/tools/testing/selftests/kvm
    [root@virtlab-arm01 kvm]# ./aarch64/sdei 

        NR_VCPUS: 2    SDEI Event: 0x00000000

    --- VERSION
        Version:              1.1 (vendor: 0x4b564d)
    --- FEATURES
        Shared event slots:   0
        Private event slots:  0
        Relative mode:        No
    --- PRIVATE_RESET
    --- SHARED_RESET
    --- PE_UNMASK
    --- EVENT_GET_INFO
        Type:                 Private
        Priority:             Normal
        Signaled:             Yes
    --- EVENT_REGISTER
    --- EVENT_ENABLE
    --- EVENT_SIGNAL
        Handled:              Yes
        IRQ:                  No
        Status:               Registered-Enabled-Running
        PC/PSTATE:            000000000040232c 00000000600003c5
        Regs:                 0000000000000000 0000000000000000
                              0000000000000000 0000000000000000
    --- PE_MASK
    --- EVENT_DISABLE
    --- EVENT_UNREGISTER

        Result: OK

[2] There are additional patches in the following repositories to create
    procfs entries, allowing to inject SDEI event from host side. The
    SDEI client in the guest side registers the SDEI default event, whose
    number is zero. Also, the QEMU exports SDEI ACPI table and supports
    migration for SDEI.

    https://github.com/gwshan/linux    ("kvm/arm64_sdei")
    https://github.com/gwshan/qemu     ("kvm/arm64_sdei")

    [2.1] Start the guests and migrate the source VM to the destination
          VM.

    [host]# /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64       \
            -accel kvm -machine virt,gic-version=host                     \
            -cpu host -smp 6,sockets=2,cores=3,threads=1                  \
            -m 1024M,slots=16,maxmem=64G                                  \
               :                                                          \
            -kernel /home/gavin/sandbox/linux.guest/arch/arm64/boot/Image \
            -initrd /home/gavin/sandbox/images/rootfs.cpio.xz             \
            -append earlycon=pl011,mmio,0x9000000                         \
               :

    [host]# /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64       \
            -accel kvm -machine virt,gic-version=host                     \
            -cpu host -smp 6,sockets=2,cores=3,threads=1                  \
            -m 1024M,slots=16,maxmem=64G                                  \
               :                                                          \
            -kernel /home/gavin/sandbox/linux.guest/arch/arm64/boot/Image \
            -initrd /home/gavin/sandbox/images/rootfs.cpio.xz             \
            -append earlycon=pl011,mmio,0x9000000                         \
            -incoming tcp:0:4444                                          \
               :

    [2.2] Check kernel log on the source VM. The SDEI service is enabled
          and the default SDEI event (0x0) is enabled.

     [guest-src]# dmesg | grep -i sdei
     ACPI: SDEI 0x000000005BC80000 000024 \
                (v00 BOCHS  BXPC     00000001 BXPC 00000001)
     sdei: SDEIv1.1 (0x4b564d) detected in firmware.
     SDEI TEST: Version 1.1, Vendor 0x4b564d
     sdei_init: SDEI event (0x0) registered
     sdei_init: SDEI event (0x0) enabled

 
     (qemu) migrate -d tcp:localhost:4444

    [2.3] Migrate the source VM to the destination VM. Inject SDEI event
          to the destination VM. The event is raised and handled.

    (qemu) migrate -d tcp:localhost:4444

    [host]# echo 0 > /proc/kvm/kvm-5360/vcpu-1

    [guest-dst]#
    =========== SDEI Event (CPU#1) ===========
    Event: 0000000000000000  Parameter: 00000000dabfdabf
    PC: ffff800008cbb554  PSTATE: 00000000604000c5  SP: ffff800009c7bde0
    Regs:    00000000000016ee ffff00001ffd2e28 00000000000016ed 0000000000000001 
             ffff800016c28000 0000000000000000 0000000000000000 0000000000000000 
             0000000000000000 0000000000000000 0000000000000000 0000000000000000 
             0000000000000000 0000000000000000 0000000000000000 0000000000000000 
             0000000000000000 0000000000000000 0000000000000000 ffff800009399008 
             ffff8000097d9af0 ffff8000097d99f8 ffff8000093a8db8 ffff8000097d9b18 
             0000000000000000 0000000000000000 ffff000000339d00 0000000000000000 
             0000000000000000 ffff800009c7bde0 ffff800008cbb5c4 
    Context: 00000000000016ee ffff00001ffd2e28 00000000000016ed 0000000000000001 
             ffff800016c28000 03ffffffffffffff 000000024325db59 ffff8000097de190 
             ffff00000033a790 ffff800008cbb814 0000000000000a30 0000000000000000 

Changelog
========= 
v6:
   * Rebased to v5.18.rc1                                     (Gavin)
   * Pass additional argument to smccc_get_arg()              (Oliver) 
   * Add preparatory patch to route hypercalls based on their
     owners                                                   (Oliver)
   * Remove the support for shared event.                     (Oliver/Gavin)
   * Remove the support for migration and add-on patches to
     support it in future                                     (Oliver)
   * The events are exposed by KVM instead of VMM             (Oliver)
   * kvm_sdei_state.h is dropped and all the structures are
     folded into the corresponding ones in kvm_sdei.h         (Oliver)
   * Rename 'struct kvm_sdei_registered_event' to
     'struct kvm_sdei_event'                                  (Oliver)
   * Misc comments from Oliver Upon                           (Oliver)  
v5:
   * Rebased to v5.17.rc7                                     (Gavin)
   * Unified names for the objects, data structures, variables
     and functions. The events have been named as exposed,
     registered and vcpu event. The staes needs to be migrated
     is put into kvm_sdei_state.h                             (Eric)
   * More inline functions to visit SDEI event's properties   (Eric)
   * Support unregistration pending state                     (Eric)
   * Support v1.1 SDEI specification                          (Eric)
   * Fold the code to inject, deliver and handle SDEI event
     from PATCH[v4 13/18/19] into PATCH[v5 13]                (Eric)
   * Simplified ioctl interface to visit all events at once   (Eric/Gavin)
   * Improved reference count and avoid its migration. Also,
     the limit to memory allocation is added based on it.     (Eric)
   * Change the return values from hypercall functions        (Eric) 
   * Validate @ksdei and @vsdi in kvm_sdei_hypercall()        (Shannon)
   * Add document to explain how SDEI virtualization and the
     migration are supported                                  (Eric)
   * Improved selftest case to inject and handle SDEI event   (Gavin)
   * Improved comments and commit logs                        (Eric)
   * Address misc comments from Eric. Hopefully, all of them
     are covered in v5 because Eric provided lots of comments
     in the last round of review                              (Eric)
v4:
   * Rebased to v5.14.rc5                                     (Gavin)
v3:
   * Rebased to v5.13.rc1                                     (Gavin)
   * Use linux data types in kvm_sdei.h                       (Gavin)
v2:
   * Rebased to v5.11.rc6                                     (Gavin)
   * Dropped changes related to SDEI client driver            (Gavin)
   * Removed support for passthrou SDEI events                (Gavin)
   * Redesigned data structures                               (Gavin)
   * Implementation is almost rewritten as the data
     structures are totally changed                           (Gavin)
   * Added ioctl commands to support migration                (Gavin)

Gavin Shan (18):
  KVM: arm64: Extend smccc_get_argx()
  KVM: arm64: Route hypercalls based on their owner
  KVM: arm64: Add SDEI virtualization infrastructure
  KVM: arm64: Support SDEI_EVENT_REGISTER hypercall
  KVM: arm64: Support SDEI_EVENT_{ENABLE, DISABLE}
  KVM: arm64: Support SDEI_EVENT_CONTEXT hypercall
  KVM: arm64: Support SDEI_EVENT_UNREGISTER hypercall
  KVM: arm64: Support SDEI_EVENT_STATUS hypercall
  KVM: arm64: Support SDEI_EVENT_GET_INFO hypercall
  KVM: arm64: Support SDEI_PE_{MASK, UNMASK} hypercall
  KVM: arm64: Support SDEI_{PRIVATE, SHARED}_RESET
  KVM: arm64: Support SDEI event injection, delivery
  KVM: arm64: Support SDEI_EVENT_{COMPLETE,COMPLETE_AND_RESUME}
    hypercall
  KVM: arm64: Support SDEI_EVENT_SIGNAL hypercall
  KVM: arm64: Support SDEI_FEATURES hypercall
  KVM: arm64: Support SDEI_VERSION hypercall
  KVM: arm64: Expose SDEI capability
  KVM: selftests: Add SDEI test case

 Documentation/virt/kvm/api.rst             |  11 +
 arch/arm64/include/asm/kvm_emulate.h       |   1 +
 arch/arm64/include/asm/kvm_host.h          |   3 +
 arch/arm64/include/asm/kvm_sdei.h          | 155 ++++
 arch/arm64/kvm/Makefile                    |   2 +-
 arch/arm64/kvm/arm.c                       |   8 +
 arch/arm64/kvm/hyp/exception.c             |   7 +
 arch/arm64/kvm/hypercalls.c                | 204 +++--
 arch/arm64/kvm/inject_fault.c              |  29 +
 arch/arm64/kvm/psci.c                      |  14 +-
 arch/arm64/kvm/pvtime.c                    |   2 +-
 arch/arm64/kvm/sdei.c                      | 902 +++++++++++++++++++++
 arch/arm64/kvm/trng.c                      |   4 +-
 include/kvm/arm_hypercalls.h               |  19 +-
 include/uapi/linux/arm_sdei.h              |   4 +
 include/uapi/linux/kvm.h                   |   1 +
 tools/testing/selftests/kvm/Makefile       |   1 +
 tools/testing/selftests/kvm/aarch64/sdei.c | 498 ++++++++++++
 18 files changed, 1767 insertions(+), 98 deletions(-)
 create mode 100644 arch/arm64/include/asm/kvm_sdei.h
 create mode 100644 arch/arm64/kvm/sdei.c
 create mode 100644 tools/testing/selftests/kvm/aarch64/sdei.c

-- 
2.23.0