On Thu, Dec 08, 2016 at 04:23:15PM +0100, Andrew Jones wrote: > The spec for ID_DFR0_EL1 says "In an AArch64-only implementation, > this register is UNKNOWN." Indeed ThunderX just returns zero when > that register is read. That means we can't rely on a non-zero > value to determine if we can test the PMU. As the pmu-version is > only needed by ARM/AArch32, then if we're running AArch64 code, > we can return true from pmu_probe() even when pmu-version is zero. > > Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx> > > --- > Applies on top of not-yet-merged > https://lists.gnu.org/archive/html/qemu-devel/2016-12/msg00811.html > --- > arm/pmu.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/arm/pmu.c b/arm/pmu.c > index a39dae43c99e..a0597c5b7806 100644 > --- a/arm/pmu.c > +++ b/arm/pmu.c > @@ -37,6 +37,7 @@ > > static unsigned int pmu_version; > #if defined(__arm__) > +#define is_aarch64() (false) > #define PMCR __ACCESS_CP15(c9, 0, c12, 0) > #define ID_DFR0 __ACCESS_CP15(c0, 0, c1, 2) > #define PMSELR __ACCESS_CP15(c9, 0, c12, 5) > @@ -95,6 +96,7 @@ static inline void precise_instrs_loop(int loop, uint32_t pmcr) > : "cc"); > } > #elif defined(__aarch64__) > +#define is_aarch64() (true) > static inline uint32_t get_id_dfr0(void) { return read_sysreg(id_dfr0_el1); } > static inline uint32_t get_pmcr(void) { return read_sysreg(pmcr_el0); } > static inline void set_pmcr(uint32_t v) { write_sysreg(v, pmcr_el0); } > @@ -265,7 +267,7 @@ bool pmu_probe(void) > if (pmu_version) > report_info("PMU version: %d", pmu_version); > > - return pmu_version; > + return pmu_version || is_aarch64(); Hrm, to keep the probe useful for aarch64, I guess I should look at ID_AA64DFR0_EL1. Will spin a v2 with Wei's [offline] suggestion to introduce a get_pmu_version() function. > } > > int main(int argc, char *argv[]) > -- > 2.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
