Subject: Re: [kvm-unit-tests PATCH v9 27/31] powerpc: add pmu tests

From: "Nicholas Piggin" <[email-masked]>
Date: Wed, 05 Jun 2024 11:12:00 +1000

On Tue Jun 4, 2024 at 8:38 PM AEST, Thomas Huth wrote:
> On 04/05/2024 14.28, Nicholas Piggin wrote:
> > Add some initial PMU testing.
> > 
> > - PMC5/6 tests
> > - PMAE / PMI test
> > - BHRB basic tests
> > 
> > Signed-off-by: Nicholas Piggin <[email-masked]>
> > ---
> ...
> > diff --git a/lib/powerpc/setup.c b/lib/powerpc/setup.c
> > index a4ff678ce..8ff4939e2 100644
> > --- a/lib/powerpc/setup.c
> > +++ b/lib/powerpc/setup.c
> > @@ -33,6 +33,7 @@ u32 initrd_size;
> >   u32 cpu_to_hwid[NR_CPUS] = { [0 ... NR_CPUS-1] = (~0U) };
> >   int nr_cpus_present;
> >   uint64_t tb_hz;
> > +uint64_t cpu_hz;
> >   
> >   struct mem_region mem_regions[NR_MEM_REGIONS];
> >   phys_addr_t __physical_start, __physical_end;
> > @@ -42,6 +43,7 @@ struct cpu_set_params {
> >   	unsigned icache_bytes;
> >   	unsigned dcache_bytes;
> >   	uint64_t tb_hz;
> > +	uint64_t cpu_hz;
> >   };
> >   
> >   static void cpu_set(int fdtnode, u64 regval, void *info)
> > @@ -95,6 +97,22 @@ static void cpu_set(int fdtnode, u64 regval, void *info)
> >   		data = (u32 *)prop->data;
> >   		params->tb_hz = fdt32_to_cpu(*data);
> >   
> > +		prop = fdt_get_property(dt_fdt(), fdtnode,
> > +					"ibm,extended-clock-frequency", NULL);
> > +		if (prop) {
> > +			data = (u32 *)prop->data;
> > +			params->cpu_hz = fdt32_to_cpu(*data);
> > +			params->cpu_hz <<= 32;
> > +			data = (u32 *)prop->data + 1;
> > +			params->cpu_hz |= fdt32_to_cpu(*data);
>
> Why don't you simply cast to (u64 *) and use fdt64_to_cpu() here instead?

Hmm... probably because I copied from somewhere. Good idea though.

>
> ...
> > diff --git a/powerpc/pmu.c b/powerpc/pmu.c
> > new file mode 100644
> > index 000000000..8b13ee4cd
> > --- /dev/null
> > +++ b/powerpc/pmu.c
> > @@ -0,0 +1,403 @@
> ...
> > +static void test_pmc5_with_fault(void)
> > +{
> > +	unsigned long pmc5_1, pmc5_2;
> > +
> > +	handle_exception(0x700, &illegal_handler, NULL);
> > +	handle_exception(0xe40, &illegal_handler, NULL);
> > +
> > +	reset_mmcr0();
> > +	mtspr(SPR_PMC5, 0);
> > +	mtspr(SPR_MMCR0, mfspr(SPR_MMCR0) & ~(MMCR0_FC | MMCR0_FC56));
> > +	asm volatile(".long 0x0" ::: "memory");
> > +	mtspr(SPR_MMCR0, mfspr(SPR_MMCR0) | (MMCR0_FC | MMCR0_FC56));
> > +	assert(got_interrupt);
> > +	got_interrupt = false;
> > +	pmc5_1 = mfspr(SPR_PMC5);
> > +
> > +	reset_mmcr0();
> > +	mtspr(SPR_PMC5, 0);
> > +	mtspr(SPR_MMCR0, mfspr(SPR_MMCR0) & ~(MMCR0_FC | MMCR0_FC56));
> > +	asm volatile(".rep 20 ; nop ; .endr ; .long 0x0" ::: "memory");
> > +	mtspr(SPR_MMCR0, mfspr(SPR_MMCR0) | (MMCR0_FC | MMCR0_FC56));
> > +	assert(got_interrupt);
> > +	got_interrupt = false;
> > +	pmc5_2 = mfspr(SPR_PMC5);
> > +
> > +	/* TCG and POWER9 do not count instructions around faults correctly */
> > +	report_kfail(true, pmc5_1 + 20 == pmc5_2, "PMC5 counts instructions with fault");
>
> It would be nice to have the TCG detection patch before this patch, so you 
> could use the right condition here right from the start.

Yeah, it turned out to be a bit annoying to rebase. We already have
some kfail(true in the tree but I will remove those at least toward
the end of the series.

I might take another look at reordering it after I rebase what you
have merged.

>
> > +	handle_exception(0x700, NULL, NULL);
> > +	handle_exception(0xe40, NULL, NULL);
> > +}
> > +
> > +static void test_pmc5_with_sc(void)
> > +{
> > +	unsigned long pmc5_1, pmc5_2;
> > +
> > +	handle_exception(0xc00, &sc_handler, NULL);
> > +
> > +	reset_mmcr0();
> > +	mtspr(SPR_PMC5, 0);
> > +	mtspr(SPR_MMCR0, mfspr(SPR_MMCR0) & ~(MMCR0_FC | MMCR0_FC56));
> > +	asm volatile("sc 0" ::: "memory");
> > +	mtspr(SPR_MMCR0, mfspr(SPR_MMCR0) | (MMCR0_FC | MMCR0_FC56));
> > +	assert(got_interrupt);
> > +	got_interrupt = false;
> > +	pmc5_1 = mfspr(SPR_PMC5);
> > +
> > +	reset_mmcr0();
> > +	mtspr(SPR_PMC5, 0);
> > +	mtspr(SPR_MMCR0, mfspr(SPR_MMCR0) & ~(MMCR0_FC | MMCR0_FC56));
> > +	asm volatile(".rep 20 ; nop ; .endr ; sc 0" ::: "memory");
> > +	mtspr(SPR_MMCR0, mfspr(SPR_MMCR0) | (MMCR0_FC | MMCR0_FC56));
> > +	assert(got_interrupt);
> > +	got_interrupt = false;
> > +	pmc5_2 = mfspr(SPR_PMC5);
> > +
> > +	/* TCG does not count instructions around syscalls correctly */
> > +	report_kfail(true, pmc5_1 + 20 == pmc5_2, "PMC5 counts instructions with syscall");
>
> dito
>
> > +	handle_exception(0xc00, NULL, NULL);
> > +}
> > +
> > +static void test_pmc56(void)
> > +{
> > +	unsigned long tmp;
> > +
> > +	report_prefix_push("pmc56");
> > +
> > +	reset_mmcr0();
> > +	mtspr(SPR_PMC5, 0);
> > +	mtspr(SPR_PMC6, 0);
> > +	report(mfspr(SPR_PMC5) == 0, "PMC5 zeroed");
> > +	report(mfspr(SPR_PMC6) == 0, "PMC6 zeroed");
> > +	mtspr(SPR_MMCR0, mfspr(SPR_MMCR0) & ~MMCR0_FC);
> > +	msleep(100);
> > +	report(mfspr(SPR_PMC5) == 0, "PMC5 frozen");
> > +	report(mfspr(SPR_PMC6) == 0, "PMC6 frozen");
> > +	mtspr(SPR_MMCR0, mfspr(SPR_MMCR0) & ~MMCR0_FC56);
> > +	mdelay(100);
> > +	mtspr(SPR_MMCR0, mfspr(SPR_MMCR0) | (MMCR0_FC | MMCR0_FC56));
> > +	report(mfspr(SPR_PMC5) != 0, "PMC5 counting");
> > +	report(mfspr(SPR_PMC6) != 0, "PMC6 counting");
> > +
> > +	/* Dynamic frequency scaling could cause to be out, so don't fail. */
> > +	tmp = mfspr(SPR_PMC6);
> > +	report(true, "PMC6 ratio to reported clock frequency is %ld%%", tmp * 1000 / cpu_hz);
>
> report(true, ...) looks weird. Use report_info() instead?

Ah yes that's better. I was going to do a pass/fail threshold but that
gets pretty arbitrary depending on DVFS.. I guess for TCG we could report
a pass/fail.

Thanks,
Nick