[PATCH 4/4] powerpc/perf: MMCR0 control for PMU registers under PMCC=00

[Athira Rajeev]

PowerISA v3.1 introduces new control bit (PMCCEXT) for enabling
secure access to group B PMU registers in problem state when
MMCR0 PMCC=0b00. This patch adds support for MMCR0 PMCCEXT bit
in power10 by enabling this bit during boot and during the PMU
event enable/disable operations when MMCR0 PMCC=0b00

Signed-off-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/reg.h        |  1 +
 arch/powerpc/kernel/cpu_setup_power.S |  2 ++
 arch/powerpc/kernel/dt_cpu_ftrs.c     |  1 +
 arch/powerpc/perf/core-book3s.c       | 16 ++++++++++++++++
 4 files changed, 20 insertions(+)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index f877a57..cba9965 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -864,6 +864,7 @@
 #define   MMCR0_BHRBA	0x00200000UL /* BHRB Access allowed in userspace */
 #define   MMCR0_EBE	0x00100000UL /* Event based branch enable */
 #define   MMCR0_PMCC	0x000c0000UL /* PMC control */
+#define   MMCR0_PMCCEXT	ASM_CONST(0x00000200) /* PMCCEXT control */
 #define   MMCR0_PMCC_U6	0x00080000UL /* PMC1-6 are R/W by user (PR) */
 #define   MMCR0_PMC1CE	0x00008000UL /* PMC1 count enable*/
 #define   MMCR0_PMCjCE	ASM_CONST(0x00004000) /* PMCj count enable*/
diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S
index 704e8b9..8fc8b72 100644
--- a/arch/powerpc/kernel/cpu_setup_power.S
+++ b/arch/powerpc/kernel/cpu_setup_power.S
@@ -249,4 +249,6 @@ __init_PMU_ISA31:
 	mtspr	SPRN_MMCR3,r5
 	LOAD_REG_IMMEDIATE(r5, MMCRA_BHRB_DISABLE)
 	mtspr	SPRN_MMCRA,r5
+	LOAD_REG_IMMEDIATE(r5, MMCR0_PMCCEXT)
+	mtspr	SPRN_MMCR0,r5
 	blr
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 1098863..9d07965 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -454,6 +454,7 @@ static void init_pmu_power10(void)
 
 	mtspr(SPRN_MMCR3, 0);
 	mtspr(SPRN_MMCRA, MMCRA_BHRB_DISABLE);
+	mtspr(SPRN_MMCR0, MMCR0_PMCCEXT);
 }
 
 static int __init feat_enable_pmu_power10(struct dt_cpu_feature *f)
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 08643cb..f328bc0 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -95,6 +95,7 @@ struct cpu_hw_events {
 #define SPRN_SIER3		0
 #define MMCRA_SAMPLE_ENABLE	0
 #define MMCRA_BHRB_DISABLE     0
+#define MMCR0_PMCCEXT		0
 
 static inline unsigned long perf_ip_adjust(struct pt_regs *regs)
 {
@@ -1242,6 +1243,9 @@ static void power_pmu_disable(struct pmu *pmu)
 		val |= MMCR0_FC;
 		val &= ~(MMCR0_EBE | MMCR0_BHRBA | MMCR0_PMCC | MMCR0_PMAO |
 			 MMCR0_FC56);
+		/* Set mmcr0 PMCCEXT for p10 */
+		if (ppmu->flags & PPMU_ARCH_31)
+			val |= MMCR0_PMCCEXT;
 
 		/*
 		 * The barrier is to make sure the mtspr has been
@@ -1449,6 +1453,18 @@ static void power_pmu_enable(struct pmu *pmu)
 
 	mmcr0 = ebb_switch_in(ebb, cpuhw);
 
+	/*
+	 * Set mmcr0 (PMCCEXT) for p10
+	 * if mmcr0 PMCC=0b00 to allow secure
+	 * mode of access to group B registers.
+	 */
+	if (ppmu->flags & PPMU_ARCH_31) {
+		if (!(mmcr0 & MMCR0_PMCC)) {
+			cpuhw->mmcr.mmcr0 |= MMCR0_PMCCEXT;
+			mmcr0 |= MMCR0_PMCCEXT;
+		}
+	}
+
 	mb();
 	if (cpuhw->bhrb_users)
 		ppmu->config_bhrb(cpuhw->bhrb_filter);
-- 
1.8.3.1