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Subject: Re: [PATCH v7 00/22] Support SDEI Virtualization
From:   Gavin Shan <gshan@redhat.com>
To:     kvmarm@lists.cs.columbia.edu
Cc:     maz@kernel.org, shijie@amperemail.onmicrosoft.com,
        linux-kernel@vger.kernel.org, eauger@redhat.com,
        shan.gavin@gmail.com, Jonathan.Cameron@huawei.com,
        pbonzini@redhat.com, vkuznets@redhat.com, will@kernel.org,
        oliver.upton@linux.dev, Oliver Upton <oupton@google.com>,
        James Morse <james.morse@arm.com>,
        Mark Rutland <mark.rutland@arm.com>
References: <20220527080253.1562538-1-gshan@redhat.com>
Message-ID: <6bdb9280-3530-dc1f-d33e-5bc1c5ac927b@redhat.com>
Date:   Thu, 23 Jun 2022 16:11:08 +1000
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Hi Oliver,

On 5/27/22 6:02 PM, Gavin Shan wrote:
> 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 critial
> events aren't supported by the implementation either. It means all events
> are normal in terms of priority.
> 
> There are several objects (data structures) introduced to help on the
> event registration, enablement, disablement, unregistration, reset,
> delivery and handling.
> 
>    * kvm_sdei_event_handler
>      SDEI event handler, which is provided through EVENT_REGISTER
>      hypercall, is called when the SDEI event is delivered from
>      host to guest.
>      
>    * kvm_sdei_event_context
>      The saved (preempted) context when SDEI event is delivered
>      for handling.
>      
>    * kvm_sdei_vcpu
>      SDEI events and their states.
> 
> 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[18-19] Support SDEI migration
>    PATCH[20]    Adds document about SDEI
>    PATCH[21-22] SDEI related selftest cases
> 
> The previous revisions can be found:
> 
>    v6: https://lore.kernel.org/lkml/20220403153911.12332-4-gshan@redhat.com/T/
>    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/
> 

Copying Oliver's new email address (oliver.upton@linux.dev).

Please let me know if I need to rebase and repost the series.

Thanks,
Gavin

> 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
> =========
> v7:
>     * Rebased to v5.19.rc1                                     (Gavin)
>     * Add hypercall ranges for routing                         (Oliver)
>     * Remove support to the critical event and redesigned
>       data structures. Function names are also modified
>       as Oliver suggested                                      (Oliver)
>     * Deliver event when it's enabled or the specific PE
>       is unmasked                                              (Oliver)
>     * Improve EVENT_COMPLETE_AND_RESUME hypercall to resume
>       from the specified address                               (Oliver)
>     * Add patches for SDEI migration and documentation         (Gavin)
>     * Misc comments from Oliver Upon                           (Oliver)
> 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/v4/v3/v2/v1:
>     * Skipped here and please visit the history by
>       https://lore.kernel.org/lkml/20220403153911.12332-4-gshan@redhat.com/T/
> 
> Gavin Shan (22):
>    KVM: arm64: Extend smccc_get_argx()
>    KVM: arm64: Route hypercalls based on their owner
>    KVM: arm64: Add SDEI virtualization infrastructure
>    KVM: arm64: Support EVENT_REGISTER hypercall
>    KVM: arm64: Support EVENT_{ENABLE, DISABLE} hypercall
>    KVM: arm64: Support EVENT_CONTEXT hypercall
>    KVM: arm64: Support EVENT_UNREGISTER hypercall
>    KVM: arm64: Support EVENT_STATUS hypercall
>    KVM: arm64: Support EVENT_GET_INFO hypercall
>    KVM: arm64: Support PE_{MASK, UNMASK} hypercall
>    KVM: arm64: Support {PRIVATE, SHARED}_RESET hypercall
>    KVM: arm64: Support event injection and delivery
>    KVM: arm64: Support EVENT_{COMPLETE, COMPLETE_AND_RESUME} hypercall
>    KVM: arm64: Support EVENT_SIGNAL hypercall
>    KVM: arm64: Support SDEI_FEATURES hypercall
>    KVM: arm64: Support SDEI_VERSION hypercall
>    KVM: arm64: Expose SDEI capbility and service
>    KVM: arm64: Allow large sized pseudo firmware registers
>    KVM: arm64: Support SDEI event migration
>    KVM: arm64: Add SDEI document
>    selftests: KVM: aarch64: Add SDEI case in hypercall tests
>    selftests: KVM: aarch64: Add SDEI test case
> 
>   Documentation/virt/kvm/api.rst                |  11 +
>   Documentation/virt/kvm/arm/hypercalls.rst     |   4 +
>   Documentation/virt/kvm/arm/sdei.rst           |  64 ++
>   arch/arm64/include/asm/kvm_host.h             |   3 +
>   arch/arm64/include/asm/kvm_sdei.h             |  81 +++
>   arch/arm64/include/uapi/asm/kvm.h             |  18 +
>   arch/arm64/kvm/Makefile                       |   2 +-
>   arch/arm64/kvm/arm.c                          |   8 +
>   arch/arm64/kvm/hypercalls.c                   | 182 +++--
>   arch/arm64/kvm/psci.c                         |  14 +-
>   arch/arm64/kvm/pvtime.c                       |   2 +-
>   arch/arm64/kvm/sdei.c                         | 676 ++++++++++++++++++
>   arch/arm64/kvm/trng.c                         |   4 +-
>   include/kvm/arm_hypercalls.h                  |  19 +-
>   include/linux/arm-smccc.h                     |   7 +
>   include/uapi/linux/arm_sdei.h                 |   8 +
>   include/uapi/linux/kvm.h                      |   1 +
>   tools/testing/selftests/kvm/Makefile          |   1 +
>   .../selftests/kvm/aarch64/hypercalls.c        |  11 +-
>   tools/testing/selftests/kvm/aarch64/sdei.c    | 450 ++++++++++++
>   20 files changed, 1499 insertions(+), 67 deletions(-)
>   create mode 100644 Documentation/virt/kvm/arm/sdei.rst
>   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
>