[PATCH v2 3/4] perf/x86/intel: Make @data a mandatory param for intel_guest_get_msrs()

Sean Christopherson
2026-04-23T15:03:50Z

Drop "support" for passing a NULL @data/@kvm_pmu param when getting guest
MSRs. KVM, the only in-tree user, unconditionally passes a non-NULL
pointer, and carrying code that suggests @data may be NULL is confusing,
e.g. incorrectly implies that there are scenarios where KVM doesn't pass
a PMU context.

Fixes: 8183a538cd95 ("KVM: x86/pmu: Add IA32_DS_AREA MSR emulation to support guest DS")
Cc: Jim Mattson <jmattson@google.com>
Cc: Mingwei Zhang <mizhang@google.com>
Cc: Stephane Eranian <eranian@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/events/intel/core.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 407fd392fd46..7403ca721b6a 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -5038,11 +5038,11 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr, void *data)
}

/*
- * If the guest won't use PEBS or the CPU doesn't support PEBS in the
- * guest, then there's nothing more to do as disabling PMCs via
- * PERF_GLOBAL_CTRL is sufficient on CPUs with guest/host isolation.
+ * If the CPU doesn't support PEBS in the guest, then there's nothing
+ * more to do as disabling PMCs via PERF_GLOBAL_CTRL is sufficient on
+ * CPUs with guest/host isolation.
*/
- if (!kvm_pmu || !x86_pmu.pebs_ept)
+ if (!x86_pmu.pebs_ept)
return arr;

/*
--
2.54.0.545.g6539524ca2-goog