From 50c8ab8d9fbf5b18d5162a797ca26568afc0af1a Mon Sep 17 00:00:00 2001
From: Tuan Phan <tuanphan@os.amperecomputing.com>
Date: Wed, 20 May 2020 10:13:07 -0700
Subject: [PATCH] ACPI/IORT: Fix PMCG node single ID mapping handling
Git-commit: 50c8ab8d9fbf5b18d5162a797ca26568afc0af1a
Patch-mainline: v5.8-rc1
References: git-fixes

An IORT PMCG node can have no ID mapping if its overflow interrupt is
wire based therefore the code that parses the PMCG node can not assume
the node will always have a single mapping present at index 0.

Fix iort_get_id_mapping_index() by checking for an overflow interrupt
and mapping count.

Fixes: 24e516049360 ("ACPI/IORT: Add support for PMCG")

Signed-off-by: Tuan Phan <tuanphan@os.amperecomputing.com>
Reviewed-by: Hanjun Guo <guoahanjun@huawei.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Link: https://lore.kernel.org/r/1589994787-28637-1-git-send-email-tuanphan@os.amperecomputing.com
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/acpi/arm64/iort.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 619a3e503346..9c40709c2f4e 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -388,6 +388,7 @@ static struct acpi_iort_node *iort_node_get_id(struct acpi_iort_node *node,
 static int iort_get_id_mapping_index(struct acpi_iort_node *node)
 {
 	struct acpi_iort_smmu_v3 *smmu;
+	struct acpi_iort_pmcg *pmcg;
 
 	switch (node->type) {
 	case ACPI_IORT_NODE_SMMU_V3:
@@ -415,6 +416,10 @@ static int iort_get_id_mapping_index(struct acpi_iort_node *node)
 
 		return smmu->id_mapping_index;
 	case ACPI_IORT_NODE_PMCG:
+		pmcg = (struct acpi_iort_pmcg *)node->node_data;
+		if (pmcg->overflow_gsiv || node->mapping_count == 0)
+			return -EINVAL;
+
 		return 0;
 	default:
 		return -EINVAL;
-- 
2.16.4