[RFC PATCH 2/6] x86/resctrl: Parse ACPI CMRC table

[Chen Yu]

The CMRC (Cache Monitoring Registers for CPU Agents Description)
sub-table of ERDT describes the MMIO registers used to read
cache monitoring counters (e.g. LLC occupancy) for an RMD.

Parse each CMRC sub-table, ioremap its register window, and save
the CMRC pointer in the corresponding ERDT domain entry so that
later monitoring code can read the counters via MMIO.

Suggested-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
---
 arch/x86/kernel/cpu/resctrl/erdt.c | 40 ++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 2813f48f1411..30b7dfd99086 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -38,6 +38,7 @@ static bool erdt_available;
 static DEFINE_XARRAY(erdt_domain_xa); /* Indexed by L3 cache ID */
 
 #define ERDT_VALID_VERSION 1
+#define CMRC_VALID_INDEX_FUNC_VERSION 1
 
 static u32 valid_subtbl_mask;
 
@@ -159,6 +160,7 @@ static void erdt_iounmap_domain(struct erdt_domain_info *domain)
 static void cleanup_one_domain(struct erdt_domain_info *d)
 {
 	erdt_iounmap_domain(d);
+	kfree(d->cmrc);
 	kfree(d);
 }
 
@@ -171,6 +173,40 @@ static __init bool cacd_init(struct erdt_domain_info *d,
 	return *l3_cache_id != -1;
 }
 
+static __init bool cmrc_init(struct erdt_domain_info *d, struct acpi_subtbl_hdr_16 *subtbl)
+{
+	struct acpi_erdt_cmrc *cmrc = (struct acpi_erdt_cmrc *)subtbl;
+
+	if (subtbl->length < sizeof(*cmrc)) {
+		pr_warn(FW_BUG "Truncated CMRC subtable\n");
+		return false;
+	}
+
+	if (cmrc->index_fn != CMRC_VALID_INDEX_FUNC_VERSION) {
+		pr_info("Unknown CMRC index function %d\n", cmrc->index_fn);
+		return false;
+	}
+
+	if (!cmrc->clump_size) {
+		pr_warn(FW_BUG "CMRC clump_size is zero\n");
+		return false;
+	}
+
+	d->base[ERDT_MMIO_CMRC_BASE] = erdt_ioremap_checked(cmrc->cmt_reg_base,
+							    cmrc->cmt_reg_size, "CMRC base");
+	if (!d->base[ERDT_MMIO_CMRC_BASE])
+		return false;
+
+	d->cmrc = kmemdup(cmrc, subtbl->length, GFP_KERNEL);
+	if (!d->cmrc) {
+		iounmap(d->base[ERDT_MMIO_CMRC_BASE]);
+		d->base[ERDT_MMIO_CMRC_BASE] = NULL;
+		return false;
+	}
+
+	return true;
+}
+
 static __init bool parse_rmdd_entry(struct acpi_subtbl_hdr_16 *rmdd_hdr)
 {
 	struct acpi_erdt_rmdd *rmdd;
@@ -219,6 +255,10 @@ static __init bool parse_rmdd_entry(struct acpi_subtbl_hdr_16 *rmdd_hdr)
 			if (cacd_init(domain_info, subtbl, &l3_cache_id))
 				subtbl_mask |= BIT(ACPI_ERDT_TYPE_CACD);
 			break;
+		case ACPI_ERDT_TYPE_CMRC:
+			if (cmrc_init(domain_info, subtbl))
+				subtbl_mask |= BIT(ACPI_ERDT_TYPE_CMRC);
+			break;
 		default:
 			break;
 		}
-- 
2.25.1