From: Prashanth Prakash <pprakash@codeaurora.org>
Date: Wed, 4 Apr 2018 12:14:51 -0600
Subject: ACPI / CPPC: Check for valid PCC subspace only if PCC is used

Git-commit: 6fa12d584dcba18f67425ce17e9317311a624f81
Patch-mainline: v4.18-rc1
References: bsc#1117115

Changes the behavior where we return error if there are no valid PCC
subspace for a given performance domain.

The ACPI spec does not mandate the use PCC, so it is possible to have
platforms where a PCC subspace may not be present, so we need to check
for a valid PCC subspace ID only if the register is a PCC register.

Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 drivers/acpi/cppc_acpi.c |   30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1040,15 +1040,14 @@ int cppc_get_perf_caps(int cpunum, struc
 		*lowest_non_linear_reg, *nominal_reg;
 	u64 high, low, nom, min_nonlinear;
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
-	struct cppc_pcc_data *pcc_ss_data;
+	struct cppc_pcc_data *pcc_ss_data = NULL;
 	int ret = 0, regs_in_pcc = 0;
 
-	if (!cpc_desc || pcc_ss_id < 0) {
+	if (!cpc_desc) {
 		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
 		return -ENODEV;
 	}
 
-	pcc_ss_data = pcc_data[pcc_ss_id];
 	highest_reg = &cpc_desc->cpc_regs[HIGHEST_PERF];
 	lowest_reg = &cpc_desc->cpc_regs[LOWEST_PERF];
 	lowest_non_linear_reg = &cpc_desc->cpc_regs[LOW_NON_LINEAR_PERF];
@@ -1057,6 +1056,11 @@ int cppc_get_perf_caps(int cpunum, struc
 	/* Are any of the regs PCC ?*/
 	if (CPC_IN_PCC(highest_reg) || CPC_IN_PCC(lowest_reg) ||
 		CPC_IN_PCC(lowest_non_linear_reg) || CPC_IN_PCC(nominal_reg)) {
+		if (pcc_ss_id < 0) {
+			pr_debug("Invalid pcc_ss_id\n");
+			return -ENODEV;
+		}
+		pcc_ss_data = pcc_data[pcc_ss_id];
 		regs_in_pcc = 1;
 		down_write(&pcc_ss_data->pcc_lock);
 		/* Ring doorbell once to update PCC subspace */
@@ -1101,16 +1105,15 @@ int cppc_get_perf_ctrs(int cpunum, struc
 	struct cpc_register_resource *delivered_reg, *reference_reg,
 		*ref_perf_reg, *ctr_wrap_reg;
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
-	struct cppc_pcc_data *pcc_ss_data;
+	struct cppc_pcc_data *pcc_ss_data = NULL;
 	u64 delivered, reference, ref_perf, ctr_wrap_time;
 	int ret = 0, regs_in_pcc = 0;
 
-	if (!cpc_desc || pcc_ss_id < 0) {
+	if (!cpc_desc) {
 		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
 		return -ENODEV;
 	}
 
-	pcc_ss_data = pcc_data[pcc_ss_id];
 	delivered_reg = &cpc_desc->cpc_regs[DELIVERED_CTR];
 	reference_reg = &cpc_desc->cpc_regs[REFERENCE_CTR];
 	ref_perf_reg = &cpc_desc->cpc_regs[REFERENCE_PERF];
@@ -1126,6 +1129,11 @@ int cppc_get_perf_ctrs(int cpunum, struc
 	/* Are any of the regs PCC ?*/
 	if (CPC_IN_PCC(delivered_reg) || CPC_IN_PCC(reference_reg) ||
 		CPC_IN_PCC(ctr_wrap_reg) || CPC_IN_PCC(ref_perf_reg)) {
+		if (pcc_ss_id < 0) {
+			pr_debug("Invalid pcc_ss_id\n");
+			return -ENODEV;
+		}
+		pcc_ss_data = pcc_data[pcc_ss_id];
 		down_write(&pcc_ss_data->pcc_lock);
 		regs_in_pcc = 1;
 		/* Ring doorbell once to update PCC subspace */
@@ -1176,15 +1184,14 @@ int cppc_set_perf(int cpu, struct cppc_p
 	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
 	struct cpc_register_resource *desired_reg;
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
-	struct cppc_pcc_data *pcc_ss_data;
+	struct cppc_pcc_data *pcc_ss_data = NULL;
 	int ret = 0;
 
-	if (!cpc_desc || pcc_ss_id < 0) {
+	if (!cpc_desc) {
 		pr_debug("No CPC descriptor for CPU:%d\n", cpu);
 		return -ENODEV;
 	}
 
-	pcc_ss_data = pcc_data[pcc_ss_id];
 	desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
 
 	/*
@@ -1195,6 +1202,11 @@ int cppc_set_perf(int cpu, struct cppc_p
 	 * achieve that goal here
 	 */
 	if (CPC_IN_PCC(desired_reg)) {
+		if (pcc_ss_id < 0) {
+			pr_debug("Invalid pcc_ss_id\n");
+			return -ENODEV;
+		}
+		pcc_ss_data = pcc_data[pcc_ss_id];
 		down_read(&pcc_ss_data->pcc_lock); /* BEGIN Phase-I */
 		if (pcc_ss_data->platform_owns_pcc) {
 			ret = check_pcc_chan(pcc_ss_id, false);