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SubjectRe: [PATCH kvm-unit-tests] x86/pmu: Add Intel Guest Transactional (commited) cycles testcase
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On 12/7/2022 3:15 PM, Like Xu wrote:
> From: Like Xu <likexu@tencent.com>
>
> On Intel platforms with TSX feature, pmu users in guest can collect
> the commited or total transactional cycles for a tsx-enabled workload,
> adding new test cases to cover them, as they are not strictly the same
> as normal hardware events from the KVM implementation point of view.
>
> Signed-off-by: Like Xu <likexu@tencent.com>
> ---
> x86/pmu.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 72 insertions(+), 1 deletion(-)
>
> diff --git a/x86/pmu.c b/x86/pmu.c
> index 72c2c9c..d4c6813 100644
> --- a/x86/pmu.c
> +++ b/x86/pmu.c
> @@ -20,7 +20,7 @@
>
> typedef struct {
> uint32_t ctr;
> - uint32_t config;
> + uint64_t config;
> uint64_t count;
> int idx;
> } pmu_counter_t;
> @@ -547,6 +547,76 @@ static void check_emulated_instr(void)
> report_prefix_pop();
> }
>
> +#define _XBEGIN_STARTED (~0u)
> +
> +static inline int _xbegin(void)
> +{
> + int ret = _XBEGIN_STARTED;
> + asm volatile(".byte 0xc7,0xf8 ; .long 0" : "+a" (ret) :: "memory");
> + return ret;
> +}
> +
> +static inline void _xend(void)
> +{
> + asm volatile(".byte 0x0f,0x01,0xd5" ::: "memory");
> +}
> +
> +int *ptr;
> +
> +static void tsx_fault(void)
> +{
> + int value = 0;
> +
> + ptr = NULL;
> + if(_xbegin() == _XBEGIN_STARTED) {
> + value++;
> + // causes abort
> + *ptr = value;
> + _xend();
> + }
> +}
> +
> +static void tsx_normal(void)
> +{
> + int value = 0;
> +
> + if(_xbegin() == _XBEGIN_STARTED) {
> + value++;
> + _xend();
> + }
> +}
> +
> +static void check_tsx_cycles(void)
> +{
> + pmu_counter_t cnt;
> + int i;
> +
> + if (!this_cpu_has(X86_FEATURE_RTM) || !this_cpu_has(X86_FEATURE_HLE))
> + return;
Since the test case is for xbegin/xend, HLE check may omit as it's for
other X-instructions.
> +
> + report_prefix_push("TSX cycles");
> +
> + for (i = 0; i < pmu.nr_gp_counters; i++) {
> + cnt.ctr = MSR_GP_COUNTERx(i);
> +
> + if (i == 2)
> + /* Transactional cycles commited only on gp counter 2 */
> + cnt.config = EVNTSEL_OS | EVNTSEL_USR | 0x30000003c;
> + else
> + /* Transactional cycles */
> + cnt.config = EVNTSEL_OS | EVNTSEL_USR | 0x10000003c;
> +
> + start_event(&cnt);
> + tsx_fault();
> + tsx_normal();
> + stop_event(&cnt);
> +
> + report(cnt.count > 0, "gp cntr-%d", i);
The purpose is to collect total cycles, why not print out the data here
for each GP counter?
> + }
> +
> + report_prefix_pop();
> +}
> +
> static void check_counters(void)
> {
> if (is_fep_available())
> @@ -559,6 +629,7 @@ static void check_counters(void)
> check_counter_overflow();
> check_gp_counter_cmask();
> check_running_counter_wrmsr();
> + check_tsx_cycles();
> }
>
> static void do_unsupported_width_counter_write(void *index)

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