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

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Message-ID: <42d93855-50df-a686-85c5-5552ff829977@loongson.cn>
Date: Mon, 24 Nov 2025 09:55:50 +0800
From: Bibo Mao <maobibo@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>,
 "open list:LOONGARCH" <loongarch@...ts.linux.dev>
Cc: 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 2025/11/21 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.

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
>>