Re: [PATCH v3 0/6] KVM: LoongArch: selftests: Add timer test case
From: Bibo Mao
Date: Wed Nov 26 2025 - 20:08:33 EST
On 2025/11/26 下午9:43, Huacai Chen wrote:
On Mon, Nov 24, 2025 at 10:17 AM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:It can be solved by modifying udelay() method with get_cycles() or using cpu loop calculation method.
Any updates available?
On 2025/11/24 上午10:03, Huacai Chen wrote:
On Mon, Nov 24, 2025 at 9:58 AM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:I think this series need be updated, test success criteria with period
Then this series need to be updated, or problem comes from other places?
On 2025/11/21 下午10:08, Huacai Chen wrote:
Hi, Bibo,There is problem with that. In generic the vCPU task is rescheduled on
On Thu, Nov 20, 2025 at 2:58 PM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
I test this series on top of 6.18-rc6 with Loongson-3A5000, sometimes
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.
it passes, sometimes I get:
[root@fedora 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?
other CPUs or preempted, so period timer interrupt is not handled in
specified time.
timer need consider this situation. Let me check how to handle this.
--- a/tools/testing/selftests/kvm/include/loongarch/arch_timer.h
+++ b/tools/testing/selftests/kvm/include/loongarch/arch_timer.h
@@ -71,10 +71,17 @@ static inline void timer_irq_disable(void)
static inline void __delay(uint64_t cycles)
{
- uint64_t start = timer_get_cycles();
-
- while ((timer_get_cycles() - start) < cycles)
- cpu_relax();
+ uint64_t start, next, loops = 0;
+
+ start = timer_get_cycles();
+ while (loops < cycles) {
+ next = timer_get_cycles();
+ /* only count one cycle if VM is preempted */
+ if (next > start) {
+ loops++;
+ start = next;
+ }
+ }
}
Regards
Bibo Mao
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