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

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Message-ID: <CAAhV-H5+suuN7Qf6qx6hVniy2KCnHf2rVPebR4Gxms-SbTz6Fg@mail.gmail.com>
Date: Wed, 26 Nov 2025 21:43:29 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Bibo Mao <maobibo@...ngson.cn>
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 Mon, Nov 24, 2025 at 10:17 AM Bibo Mao <maobibo@...ngson.cn> wrote:
>
>
>
> 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.
Any updates available?

Huacai

>
> 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
> >>>>
> >>
>