[RFC PATCH v6 18/35] perf: arm_spe_pmu: Add PMSIDR_EL1 to struct arm_spe_pmu

[Alexandru Elisei]

The host SPE driver might find itself lagging behind the architecture
when it comes to new features, so KVM cannot rely on the 'features'
field to completely describe the SPE implementation.

Some features are advertised in PMSIDR_EL1, so teach the driver to save a
copy of PMSIDR_EL1 in struct arm_spe_pmu, from where it will be consumed
directly by KVM.

Signed-off-by: Alexandru Elisei <alexandru.elisei at arm.com>
---
 drivers/perf/arm_spe_pmu.c       | 2 ++
 include/linux/perf/arm_spe_pmu.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
index 2ca3377538aa..d79f4a47c6f9 100644
--- a/drivers/perf/arm_spe_pmu.c
+++ b/drivers/perf/arm_spe_pmu.c
@@ -1069,6 +1069,8 @@ static void __arm_spe_pmu_dev_probe(void *info)
 
 	/* It's now safe to read PMSIDR and figure out what we've got */
 	reg = read_sysreg_s(SYS_PMSIDR_EL1);
+	spe_pmu->pmsidr_el1 = reg;
+
 	if (FIELD_GET(PMSIDR_EL1_FE, reg))
 		spe_pmu->features |= SPE_PMU_FEAT_FILT_EVT;
 
diff --git a/include/linux/perf/arm_spe_pmu.h b/include/linux/perf/arm_spe_pmu.h
index 25425249c193..7dd1f77040c2 100644
--- a/include/linux/perf/arm_spe_pmu.h
+++ b/include/linux/perf/arm_spe_pmu.h
@@ -22,6 +22,7 @@ struct arm_spe_pmu {
 	struct hlist_node			hotplug_node;
 
 	u64					pmbidr_el1;
+	u64					pmsidr_el1;
 	int					irq; /* PPI */
 	u16					pmsver;
 	u16					min_period;
-- 
2.51.2