[RFC,00/12] Add SDEI support for arm64

Message

Heyi Guo Sept. 24, 2019, 3:21 p.m. UTC

As promised, this is the first RFC patch set for arm64 SDEI support.
Key points:
- We propose to only support kvm enabled arm64 virtual machines, for
  non-kvm VMs can emulate EL3 and have Trusted Firmware run on it,
  which has a builtin SDEI dispatcher.
- New kvm capability KVM_CAP_FORWARD_HYPERCALL is added to probe if
  kvm supports forwarding hypercalls, and the capability should be
  enabled explicitly. PSCI can be set as exception for backward
  compatibility.
- We make the dispatcher as a logical device, to save the states
  during migration or save/restore operation; only one instance is
  allowed in one VM.
- We use qemu_irq as the bridge for other qemu modules to switch from
  irq injection to SDEI event trigger after VM binds the interrupt to
  SDEI event. We use qemu_irq_intercept_in() to override qemu_irq
  handler with SDEI event trigger, and a new interface
  qemu_irq_remove_intercept() is added to restore the handler to
  default one (i.e. ARM GIC).

More details are in the commit message of each patch.

Basic tests are done by emulating a watchdog timer and triggering SDEI
event in every 10s.

As this is the first rough RFC, please focus on the interfaces and
framework first. We can refine the code for several rounds after the
big things have been determined.

Please give your comments and suggestions.

Thanks,
HG

Cc: Peter Maydell <[e-mail]>
Cc: Dave Martin <[e-mail]>
Cc: Marc Zyngier <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: James Morse <[e-mail]>

Heyi Guo (12):
  linux-headers: import arm_sdei.h
  arm/sdei: add virtual device framework
  arm/sdei: add support to handle SDEI requests from guest
  arm/sdei: add system reset callback
  arm/sdei: add support to trigger event by GIC interrupt ID
  core/irq: add qemu_irq_remove_intercept interface
  arm/sdei: override qemu_irq handler when binding interrupt
  arm/sdei: add support to register interrupt bind notifier
  linux-headers/kvm.h: add capability to forward hypercall
  arm/sdei: check KVM cap and enable SDEI
  arm/kvm: handle guest exit of hypercall
  virt/acpi: add SDEI table if SDEI is enabled

 hw/arm/virt-acpi-build.c       |   16 +
 hw/core/irq.c                  |   11 +
 include/hw/acpi/acpi-defs.h    |    5 +
 include/hw/irq.h               |    8 +-
 linux-headers/linux/arm_sdei.h |   73 ++
 linux-headers/linux/kvm.h      |    3 +
 target/arm/Makefile.objs       |    1 +
 target/arm/kvm.c               |   17 +
 target/arm/sdei.c              | 1518 ++++++++++++++++++++++++++++++++++++++++
 target/arm/sdei.h              |   60 ++
 target/arm/sdei_int.h          |  109 +++
 11 files changed, 1819 insertions(+), 2 deletions(-)
 create mode 100644 linux-headers/linux/arm_sdei.h
 create mode 100644 target/arm/sdei.c
 create mode 100644 target/arm/sdei.h
 create mode 100644 target/arm/sdei_int.h

Comments

[e-mail] Sept. 25, 2019, 6:54 a.m. UTC | #1

Patchew URL: https://patchew.org/QEMU/[e-mail]/



Hi,

This series failed the docker-quick@centos7 build test. Please find the testing commands and
their output below. If you have Docker installed, you can probably reproduce it
locally.

=== TEST SCRIPT BEGIN ===
#!/bin/bash
make docker-image-centos7 V=1 NETWORK=1
time make docker-test-quick@centos7 SHOW_ENV=1 J=14 NETWORK=1
=== TEST SCRIPT END ===

libudev           no
default devices   yes

warning: Python 2 support is deprecated
warning: Python 3 will be required for building future versions of QEMU
cross containers  no

NOTE: guest cross-compilers enabled: cc
---
  LINK    aarch64-softmmu/qemu-system-aarch64
hw/arm/virt-acpi-build.o: In function `virt_acpi_build':
/tmp/qemu-test/src/hw/arm/virt-acpi-build.c:810: undefined reference to `sdei_enabled'
collect2: error: ld returned 1 exit status
make[1]: *** [qemu-system-aarch64] Error 1
make: *** [aarch64-softmmu/all] Error 2
Traceback (most recent call last):


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http://patchew.org/logs/[e-mail]/testing.docker-quick@centos7/?type=message.
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[e-mail] Sept. 25, 2019, 6:58 a.m. UTC | #2

Patchew URL: https://patchew.org/QEMU/[e-mail]/



Hi,

This series failed the docker-mingw@fedora build test. Please find the testing commands and
their output below. If you have Docker installed, you can probably reproduce it
locally.

=== TEST SCRIPT BEGIN ===
#! /bin/bash
export ARCH=x86_64
make docker-image-fedora V=1 NETWORK=1
time make docker-test-mingw@fedora J=14 NETWORK=1
=== TEST SCRIPT END ===

  CC      aarch64-softmmu/hw/arm/tosa.o
  CC      aarch64-softmmu/hw/arm/z2.o
In file included from /tmp/qemu-test/src/hw/arm/virt-acpi-build.c:35:
/tmp/qemu-test/src/target/arm/sdei.h:26:10: fatal error: linux/kvm.h: No such file or directory
 #include <linux/kvm.h>
          ^~~~~~~~~~~~~
compilation terminated.


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http://patchew.org/logs/[e-mail]/testing.docker-mingw@fedora/?type=message.
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Peter Maydell Sept. 30, 2019, 1:15 p.m. UTC | #3

On Tue, 24 Sep 2019 at 16:23, Heyi Guo <[e-mail]> wrote:
>
> As promised, this is the first RFC patch set for arm64 SDEI support.

Hi; for the benefit of possible reviewers who aren't familiar
with every corner of the arm ecosystem, could you provide a
summary of:
 * what is SDEI ?
 * what do KVM and QEMU want/need to do with it ?
 * what is this patchset trying to solve ?

That would provide some useful context for trying to
review the patchset.

thanks
-- PMM

Heyi Guo Oct. 9, 2019, 1:42 p.m. UTC | #4

On 2019/9/30 21:15, Peter Maydell wrote:
> On Tue, 24 Sep 2019 at 16:23, Heyi Guo <[e-mail]> wrote:
>> As promised, this is the first RFC patch set for arm64 SDEI support.
> Hi; for the benefit of possible reviewers who aren't familiar
> with every corner of the arm ecosystem, could you provide a
> summary of:
>   * what is SDEI ?
SDEI is for ARM "Software Delegated Exception Interface". AS ARM64 
doesn't have native non-maskable interrupt (NMI), we can rely on higher 
privileged software to change the pc of lower privileged software on 
certain events occur, to emulate NMI mechanism, and SDEI is the standard 
interfaces between the two levels of privileged software. It is based on 
SMC/HVC calls.

In virtualization situation, guest OS is the lower privileged software 
and hypervisor is the higher one. Major interfaces provided by SDEI include:
1. interrupt bind: guest OS can request to bind an interrupt to an SDEI 
event.
2. register: guest OS can request to register a handler to an SDEI 
event, so hypervisor will change pc of guest to this handler when 
certain event occurs.
3. complete: guest OS notifies hypervisor that it has completed the 
event handling, so hypervisor will restore the context of guest when it 
is interrupted.
>   * what do KVM and QEMU want/need to do with it ?
KVM is supposed to pass SMC/HVC calls to qemu, and qemu will serve the 
SDEI requests after parsing SMC/HVC calls. qemu also takes the 
responsibility to trigger the events. If an interrupt is requested to be 
bound to an event, qemu should not inject the interrupt to guest any 
more; instead, it should save the context of VCPU and change the PC to 
event handler which is registered by guest, and then return to guest.

To make the conversion of interrupt to SDEI event transparent to other 
modules in qemu, we used qemu_irq and qemu_irq_intercept_in() to 
override the default irq handler with SDEI event trigger. I saw 
qemu_irq_intercept_in() should be only used in qemu MST, but it seemed 
fit to override interrupt injection with event trigger after guest 
requests to bind interrupt to SDEI event.
>   * what is this patchset trying to solve ?
This patchset is trying to implement the whole SDEI framework in qemu 
with KVM enabled, including all SDEI v1.0 interfaces, as well as event 
trigger conduit from other qemu devices after interrupt binding.

I will also provide the above context in the cover letter of v2 RFC.

Thanks,

Heyi

>
> That would provide some useful context for trying to
> review the patchset.
>
> thanks
> -- PMM
>
> .
>