linux-kernel - Re: [PATCH v3 0/6] KVM: LoongArch: selftests: Add timer test case

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Message-ID: <1605b5eb-5f43-62ff-28c5-192f2f0f938d@loongson.cn>
Date: Mon, 24 Nov 2025 10:14:41 +0800
From: Bibo Mao <maobibo@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: "open list:LOONGARCH" <loongarch@...ts.linux.dev>,
 Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson
 <seanjc@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 0/6] KVM: LoongArch: selftests: Add timer test case



On 2025/11/24 上午10:03, Huacai Chen wrote:
> On Mon, Nov 24, 2025 at 9:58 AM Bibo Mao <maobibo@...ngson.cn> wrote:
>>
>>
>>
>> On 2025/11/21 下午10:08, Huacai Chen wrote:
>>> Hi, Bibo,
>>>
>>> On Thu, Nov 20, 2025 at 2:58 PM Bibo Mao <maobibo@...ngson.cn> wrote:
>>>>
>>>> This patchset adds timer test case for LoongArch system, it is based
>>>> on common arch_timer test case. And it includes one-shot and period mode
>>>> timer interrupt test, software emulated timer function and time counter
>>>> test.
>>> I test this series on top of 6.18-rc6 with Loongson-3A5000, sometimes
>>> it passes, sometimes I get:
>>> [root@...ora kvm]# ./arch_timer
>>> Random seed: 0x6b8b4567
>>> Guest assert failed,  vcpu 2; stage; 0; iter: 1
>>> ==== Test Assertion Failure ====
>>>     loongarch/arch_timer.c:79: irq_iter == 0
>>>     pid=60138 tid=60142 errno=4 - Interrupted system call
>>>        1  0x00000001200037cf: test_vcpu_run 于 arch_timer.c:70
>>>        2  0x00007ffff2449f27: ?? ??:0
>>>        3  0x00007ffff24c0633: ?? ??:0
>>>     irq_iter = 0x1.
>>>     Guest period timer interrupt was not triggered within the specified
>>>     interval, try to increase the error margin by [-e] option.
>>>
>>> Is this as expected, or something is wrong?
>> There is problem with that. In generic the vCPU task is rescheduled on
>> other CPUs or preempted, so period timer interrupt is not handled in
>> specified time.
> Then this series need to be updated, or problem comes from other places?
I think this series need be updated, test success criteria with period 
timer need consider this situation. Let me check how to handle this.

Regards
Bibo Mao
> 
> Huacai
> 
>>
>> Regards
>> Bibo Mao
>>>
>>> Hucai
>>>
>>>> ---
>>>> v2 ... v3:
>>>>     1. Adjust order about patch 2 and patch 3
>>>>     2. Add test case with alphabetical order
>>>>     3. Merge one-shot and period timer interrupt test case into one
>>>>     4. Only add LoongArch specific modification with common file
>>>>        Makefile.kvm
>>>>
>>>> v1 ... v2:
>>>>     1. Restore PC and PRMD after exception handler
>>>>     2. Split patch 4 into two small patches with period timer test and
>>>>        time counter test
>>>>     3. With time counter test, set time count with 0 when create VM. And
>>>>        verify time count starts from 0 in guest code
>>>> ---
>>>> Bibo Mao (6):
>>>>     KVM: LoongArch: selftests: Add system registers save and restore on
>>>>       exception
>>>>     KVM: LoongArch: selftests: Add basic interfaces
>>>>     KVM: LoongArch: selftests: Add exception handler register interface
>>>>     KVM: LoongArch: selftests: Add timer interrupt test case
>>>>     KVM: LoongArch: selftests: Add SW emulated timer test
>>>>     KVM: LoongArch: selftests: Add time counter test
>>>>
>>>>    tools/testing/selftests/kvm/Makefile.kvm      |   1 +
>>>>    .../kvm/include/loongarch/arch_timer.h        |  84 ++++++++
>>>>    .../kvm/include/loongarch/processor.h         |  81 +++++++-
>>>>    .../selftests/kvm/lib/loongarch/exception.S   |   6 +
>>>>    .../selftests/kvm/lib/loongarch/processor.c   |  47 ++++-
>>>>    .../selftests/kvm/loongarch/arch_timer.c      | 194 ++++++++++++++++++
>>>>    6 files changed, 410 insertions(+), 3 deletions(-)
>>>>    create mode 100644 tools/testing/selftests/kvm/include/loongarch/arch_timer.h
>>>>    create mode 100644 tools/testing/selftests/kvm/loongarch/arch_timer.c
>>>>
>>>>
>>>> base-commit: 23cb64fb76257309e396ea4cec8396d4a1dbae68
>>>> --
>>>> 2.39.3
>>>>
>>