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Message-ID: <543c8d71-e354-2737-739b-d2c1e9066527@loongson.cn>
Date: Mon, 17 Nov 2025 09:17:22 +0800
From: Bibo Mao <maobibo@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <seanjc@...gle.com>, Shuah Khan <shuah@...nel.org>,
Tianrui Zhao <zhaotianrui@...ngson.cn>, Paul Walmsley <pjw@...nel.org>,
Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
Alexandre Ghiti <alex@...ti.fr>, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, linux-kselftest@...r.kernel.org,
loongarch@...ts.linux.dev, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v2 4/7] KVM: LoongArch: selftests: Add timer test case
with one-shot mode
On 2025/11/15 下午12:10, Huacai Chen wrote:
> Hi, Bibo,
>
> On Tue, Nov 4, 2025 at 7:37 PM Bibo Mao <maobibo@...ngson.cn> wrote:
>>
>> Add timer test case based on common arch_timer code, one-shot mode
>> is tested with timer interrupt.
>>
>> Signed-off-by: Bibo Mao <maobibo@...ngson.cn>
>> ---
>> tools/testing/selftests/kvm/Makefile.kvm | 10 +-
>> .../kvm/include/loongarch/arch_timer.h | 79 +++++++++++++++
>> .../kvm/include/loongarch/processor.h | 10 ++
>> .../selftests/kvm/lib/loongarch/processor.c | 4 +-
>> .../selftests/kvm/loongarch/arch_timer.c | 98 +++++++++++++++++++
>> 5 files changed, 196 insertions(+), 5 deletions(-)
>> create mode 100644 tools/testing/selftests/kvm/include/loongarch/arch_timer.h
>> create mode 100644 tools/testing/selftests/kvm/loongarch/arch_timer.c
>>
>> diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
>> index 148d427ff24b..662adf8f309b 100644
>> --- a/tools/testing/selftests/kvm/Makefile.kvm
>> +++ b/tools/testing/selftests/kvm/Makefile.kvm
>> @@ -183,6 +183,8 @@ TEST_GEN_PROGS_arm64 += memslot_perf_test
>> TEST_GEN_PROGS_arm64 += mmu_stress_test
>> TEST_GEN_PROGS_arm64 += rseq_test
>> TEST_GEN_PROGS_arm64 += steal_time
>> +SPLIT_TESTS_arm64 += arch_timer
>> +SPLIT_TESTS_arm64 += get-reg-list
>>
>> TEST_GEN_PROGS_s390 = $(TEST_GEN_PROGS_COMMON)
>> TEST_GEN_PROGS_s390 += s390/memop
>> @@ -209,6 +211,8 @@ TEST_GEN_PROGS_riscv += memslot_perf_test
>> TEST_GEN_PROGS_riscv += mmu_stress_test
>> TEST_GEN_PROGS_riscv += rseq_test
>> TEST_GEN_PROGS_riscv += steal_time
>> +SPLIT_TESTS_riscv += arch_timer
>> +SPLIT_TESTS_riscv += get-reg-list
>>
>> TEST_GEN_PROGS_loongarch += coalesced_io_test
>> TEST_GEN_PROGS_loongarch += demand_paging_test
>> @@ -222,10 +226,10 @@ TEST_GEN_PROGS_loongarch += kvm_page_table_test
>> TEST_GEN_PROGS_loongarch += memslot_modification_stress_test
>> TEST_GEN_PROGS_loongarch += memslot_perf_test
>> TEST_GEN_PROGS_loongarch += set_memory_region_test
>> +TEST_GEN_PROGS_loongarch += arch_timer
> These tests should be in alpha-betical order.
Sure, will do in next version.
Regards
Bibo Mao
>
> Huacai
>
>> +SPLIT_TESTS_loongarch = arch_timer
>>
>> -SPLIT_TESTS += arch_timer
>> -SPLIT_TESTS += get-reg-list
>> -
>> +SPLIT_TESTS += $(SPLIT_TESTS_$(ARCH))
>> TEST_PROGS += $(TEST_PROGS_$(ARCH))
>> TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(ARCH))
>> TEST_GEN_PROGS_EXTENDED += $(TEST_GEN_PROGS_EXTENDED_$(ARCH))
>> diff --git a/tools/testing/selftests/kvm/include/loongarch/arch_timer.h b/tools/testing/selftests/kvm/include/loongarch/arch_timer.h
>> new file mode 100644
>> index 000000000000..94b1cba2744d
>> --- /dev/null
>> +++ b/tools/testing/selftests/kvm/include/loongarch/arch_timer.h
>> @@ -0,0 +1,79 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * LoongArch Constant Timer specific interface
>> + */
>> +#ifndef SELFTEST_KVM_ARCH_TIMER_H
>> +#define SELFTEST_KVM_ARCH_TIMER_H
>> +
>> +#include "processor.h"
>> +/* LoongArch timer frequency is constant 100MHZ */
>> +#define TIMER_FREQ (100UL << 20)
>> +#define msec_to_cycles(msec) (TIMER_FREQ * (unsigned long)(msec) / 1000)
>> +#define usec_to_cycles(usec) (TIMER_FREQ * (unsigned long)(usec) / 1000000)
>> +#define cycles_to_usec(cycles) ((unsigned long)(cycles) * 1000000 / TIMER_FREQ)
>> +
>> +static inline unsigned long timer_get_cycles(void)
>> +{
>> + unsigned long val = 0;
>> +
>> + __asm__ __volatile__(
>> + "rdtime.d %0, $zero\n\t"
>> + : "=r"(val)
>> + :
>> + );
>> +
>> + return val;
>> +}
>> +
>> +static inline void timer_set_next_cmp_ms(unsigned int msec, bool period)
>> +{
>> + unsigned long val;
>> +
>> + val = msec_to_cycles(msec) & CSR_TCFG_VAL;
>> + val |= CSR_TCFG_EN;
>> + if (period)
>> + val |= CSR_TCFG_PERIOD;
>> + csr_write(val, LOONGARCH_CSR_TCFG);
>> +}
>> +
>> +static inline unsigned long timer_get_val(void)
>> +{
>> + return csr_read(LOONGARCH_CSR_TVAL);
>> +}
>> +
>> +static inline unsigned long timer_get_cfg(void)
>> +{
>> + return csr_read(LOONGARCH_CSR_TCFG);
>> +}
>> +
>> +static inline void timer_irq_enable(void)
>> +{
>> + unsigned long val;
>> +
>> + val = csr_read(LOONGARCH_CSR_ECFG);
>> + val |= ECFGF_TIMER;
>> + csr_write(val, LOONGARCH_CSR_ECFG);
>> +}
>> +
>> +static inline void timer_irq_disable(void)
>> +{
>> + unsigned long val;
>> +
>> + val = csr_read(LOONGARCH_CSR_ECFG);
>> + val &= ~ECFGF_TIMER;
>> + csr_write(val, LOONGARCH_CSR_ECFG);
>> +}
>> +
>> +static inline void __delay(uint64_t cycles)
>> +{
>> + uint64_t start = timer_get_cycles();
>> +
>> + while ((timer_get_cycles() - start) < cycles)
>> + cpu_relax();
>> +}
>> +
>> +static inline void udelay(unsigned long usec)
>> +{
>> + __delay(usec_to_cycles(usec));
>> +}
>> +#endif /* SELFTEST_KVM_ARCH_TIMER_H */
>> diff --git a/tools/testing/selftests/kvm/include/loongarch/processor.h b/tools/testing/selftests/kvm/include/loongarch/processor.h
>> index b027f8f4dac7..61f6e215046b 100644
>> --- a/tools/testing/selftests/kvm/include/loongarch/processor.h
>> +++ b/tools/testing/selftests/kvm/include/loongarch/processor.h
>> @@ -83,6 +83,8 @@
>> #define LOONGARCH_CSR_PRMD 0x1
>> #define LOONGARCH_CSR_EUEN 0x2
>> #define LOONGARCH_CSR_ECFG 0x4
>> +#define ECFGB_TIMER 11
>> +#define ECFGF_TIMER (BIT_ULL(ECFGB_TIMER))
>> #define LOONGARCH_CSR_ESTAT 0x5 /* Exception status */
>> #define CSR_ESTAT_EXC_SHIFT 16
>> #define CSR_ESTAT_EXC_WIDTH 6
>> @@ -111,6 +113,14 @@
>> #define LOONGARCH_CSR_KS1 0x31
>> #define LOONGARCH_CSR_TMID 0x40
>> #define LOONGARCH_CSR_TCFG 0x41
>> +#define CSR_TCFG_VAL (BIT_ULL(48) - BIT_ULL(2))
>> +#define CSR_TCFG_PERIOD_SHIFT 1
>> +#define CSR_TCFG_PERIOD (0x1UL << CSR_TCFG_PERIOD_SHIFT)
>> +#define CSR_TCFG_EN (0x1UL)
>> +#define LOONGARCH_CSR_TVAL 0x42
>> +#define LOONGARCH_CSR_TINTCLR 0x44 /* Timer interrupt clear */
>> +#define CSR_TINTCLR_TI_SHIFT 0
>> +#define CSR_TINTCLR_TI (1 << CSR_TINTCLR_TI_SHIFT)
>> /* TLB refill exception entry */
>> #define LOONGARCH_CSR_TLBRENTRY 0x88
>> #define LOONGARCH_CSR_TLBRSAVE 0x8b
>> diff --git a/tools/testing/selftests/kvm/lib/loongarch/processor.c b/tools/testing/selftests/kvm/lib/loongarch/processor.c
>> index 20ba476ccb72..436990258068 100644
>> --- a/tools/testing/selftests/kvm/lib/loongarch/processor.c
>> +++ b/tools/testing/selftests/kvm/lib/loongarch/processor.c
>> @@ -271,8 +271,8 @@ static void loongarch_vcpu_setup(struct kvm_vcpu *vcpu)
>> TEST_FAIL("Unknown guest mode, mode: 0x%x", vm->mode);
>> }
>>
>> - /* user mode and page enable mode */
>> - val = PLV_USER | CSR_CRMD_PG;
>> + /* kernel mode and page enable mode */
>> + val = PLV_KERN | CSR_CRMD_PG;
>> loongarch_set_csr(vcpu, LOONGARCH_CSR_CRMD, val);
>> loongarch_set_csr(vcpu, LOONGARCH_CSR_PRMD, val);
>> loongarch_set_csr(vcpu, LOONGARCH_CSR_EUEN, 1);
>> diff --git a/tools/testing/selftests/kvm/loongarch/arch_timer.c b/tools/testing/selftests/kvm/loongarch/arch_timer.c
>> new file mode 100644
>> index 000000000000..2a2cebcf3885
>> --- /dev/null
>> +++ b/tools/testing/selftests/kvm/loongarch/arch_timer.c
>> @@ -0,0 +1,98 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + *
>> + * The test validates one-shot constant timer IRQ using CSR_TCFG and
>> + * CSR_TVAL registers.
>> + */
>> +#include "arch_timer.h"
>> +#include "kvm_util.h"
>> +#include "processor.h"
>> +#include "timer_test.h"
>> +#include "ucall_common.h"
>> +
>> +static void guest_irq_handler(struct ex_regs *regs)
>> +{
>> + uint64_t xcnt, val, cfg, xcnt_diff_us;
>> + unsigned int intid;
>> + uint32_t cpu = guest_get_vcpuid();
>> + struct test_vcpu_shared_data *shared_data = &vcpu_shared_data[cpu];
>> +
>> + intid = !!(regs->estat & BIT(INT_TI));
>> +
>> + /* Make sure we are dealing with the correct timer IRQ */
>> + GUEST_ASSERT_EQ(intid, 1);
>> +
>> + cfg = timer_get_cfg();
>> +
>> + /*
>> + * On physical machine, value of LOONGARCH_CSR_TVAL is BIT_ULL(48) - 1
>> + * On virtual machine, its value counts down from BIT_ULL(48) - 1
>> + */
>> + val = timer_get_val();
>> + xcnt = timer_get_cycles();
>> + xcnt_diff_us = cycles_to_usec(xcnt - shared_data->xcnt);
>> +
>> + /* Basic 'timer condition met' check */
>> + __GUEST_ASSERT(val > cfg,
>> + "val = 0x%lx, cfg = 0x%lx, xcnt_diff_us = 0x%lx",
>> + val, cfg, xcnt_diff_us);
>> +
>> + csr_write(CSR_TINTCLR_TI, LOONGARCH_CSR_TINTCLR);
>> + WRITE_ONCE(shared_data->nr_iter, shared_data->nr_iter + 1);
>> +}
>> +
>> +static void guest_test_oneshot_timer(uint32_t cpu)
>> +{
>> + uint32_t irq_iter, config_iter;
>> + uint64_t us;
>> + struct test_vcpu_shared_data *shared_data = &vcpu_shared_data[cpu];
>> +
>> + shared_data->nr_iter = 0;
>> + shared_data->guest_stage = 0;
>> + us = msecs_to_usecs(test_args.timer_period_ms) + test_args.timer_err_margin_us;
>> + for (config_iter = 0; config_iter < test_args.nr_iter; config_iter++) {
>> + shared_data->xcnt = timer_get_cycles();
>> +
>> + /* Setup the next interrupt */
>> + timer_set_next_cmp_ms(test_args.timer_period_ms, false);
>> + /* Setup a timeout for the interrupt to arrive */
>> + udelay(us);
>> +
>> + irq_iter = READ_ONCE(shared_data->nr_iter);
>> + __GUEST_ASSERT(config_iter + 1 == irq_iter,
>> + "config_iter + 1 = 0x%x, irq_iter = 0x%x.\n"
>> + " Guest timer interrupt was not triggered within the specified\n"
>> + " interval, try to increase the error margin by [-e] option.\n",
>> + config_iter + 1, irq_iter);
>> + }
>> +}
>> +
>> +static void guest_code(void)
>> +{
>> + uint32_t cpu = guest_get_vcpuid();
>> +
>> + timer_irq_enable();
>> + local_irq_enable();
>> + guest_test_oneshot_timer(cpu);
>> +
>> + GUEST_DONE();
>> +}
>> +
>> +struct kvm_vm *test_vm_create(void)
>> +{
>> + struct kvm_vm *vm;
>> + int nr_vcpus = test_args.nr_vcpus;
>> +
>> + vm = vm_create_with_vcpus(nr_vcpus, guest_code, vcpus);
>> + vm_init_descriptor_tables(vm);
>> + vm_install_exception_handler(vm, EXCCODE_INT, guest_irq_handler);
>> +
>> + /* Make all the test's cmdline args visible to the guest */
>> + sync_global_to_guest(vm, test_args);
>> + return vm;
>> +}
>> +
>> +void test_vm_cleanup(struct kvm_vm *vm)
>> +{
>> + kvm_vm_free(vm);
>> +}
>> --
>> 2.39.3
>>
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