[PATCH v7 5/9] 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 a monitoring domain.

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

Suggested-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
Tested-by: Hongyu Ning <hongyu.ning@xxxxxxxxxxxxxxx>
---
v6->v7:
    Make erdt_scale and erdt_max_rmid unsigned int. (Reinette Chatre)
    Reject an out-of-range 64-bit up_scale with a FW_BUG warning and fail
    closed instead of using max_t(int, ...). (Reinette Chatre, Tony Luck)
    Make cmrc_init() failure fail closed. (Reinette Chatre)
---
 arch/x86/include/asm/resctrl.h         |  2 +
 arch/x86/kernel/cpu/resctrl/erdt.c     | 73 ++++++++++++++++++++++++++
 arch/x86/kernel/cpu/resctrl/internal.h |  6 ++-
 3 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/resctrl.h b/arch/x86/include/asm/resctrl.h
index 575f8408a9e7..4225a518fada 100644
--- a/arch/x86/include/asm/resctrl.h
+++ b/arch/x86/include/asm/resctrl.h
@@ -49,6 +49,8 @@ DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
 DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
 DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
 
+unsigned int erdt_get_scale(void);
+
 static inline bool resctrl_arch_alloc_capable(void)
 {
 	return rdt_alloc_capable;
diff --git a/arch/x86/kernel/cpu/resctrl/erdt.c b/arch/x86/kernel/cpu/resctrl/erdt.c
index 0ce8ef85b2a0..1c477e35d044 100644
--- a/arch/x86/kernel/cpu/resctrl/erdt.c
+++ b/arch/x86/kernel/cpu/resctrl/erdt.c
@@ -23,6 +23,7 @@ static LIST_HEAD(domain_info_list);
 static bool erdt_enabled;
 
 #define ERDT_VALID_VERSION		1
+#define CMRC_SUPPORTED_INDEX_FN		1
 #define RMDD_FLAG_CPU_L3_DOMAIN		BIT(0)
 
 /* Bitmask of valid sub-tables found in the first RMDD, used to ensure all RMDDs match. */
@@ -37,11 +38,26 @@ static u16 first_rmdd_domain_id;
  */
 static unsigned int erdt_max_rmid;
 
+/*
+ * Used only by the limbo handler to round resctrl_rmid_realloc_threshold.
+ * resctrl_rmid_realloc_threshold is a single global value, and
+ * resctrl_arch_round_mon_val() takes no domain argument, so a single scale has
+ * to be derived from the per-domain cmrc->up_scale. max() is chosen because the
+ * rounding is a floor: a larger scale yields a slightly lower threshold, i.e. an
+ * RMID has to drop to a slightly lower occupancy before it is reused.
+ */
+static unsigned int erdt_scale;
+
 unsigned int erdt_get_max_rmid(void)
 {
 	return erdt_max_rmid;
 }
 
+unsigned int erdt_get_scale(void)
+{
+	return erdt_scale;
+}
+
 static void __iomem *erdt_ioremap(resource_size_t base, u32 num_pages, const char *desc)
 {
 	void __iomem *addr;
@@ -71,6 +87,7 @@ 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);
 }
 
@@ -105,6 +122,49 @@ static __init int cacd_init(struct acpi_subtbl_hdr_16 *subtbl,
 	return 0;
 }
 
+static __init int cmrc_init(struct acpi_subtbl_hdr_16 *subtbl,
+			    struct erdt_domain_info *domain_info)
+{
+	struct acpi_erdt_cmrc *cmrc = (struct acpi_erdt_cmrc *)subtbl;
+
+	if (cmrc->header.length < sizeof(*cmrc)) {
+		pr_warn(FW_BUG "Truncated CMRC sub-table\n");
+		return -EIO;
+	}
+
+	if (cmrc->index_fn != CMRC_SUPPORTED_INDEX_FN) {
+		pr_info("Unsupported CMRC index function %u\n", cmrc->index_fn);
+		return -EIO;
+	}
+
+	if (!cmrc->clump_size) {
+		pr_warn(FW_BUG "CMRC clump_size is zero\n");
+		return -EIO;
+	}
+
+	/* resctrl scales monitoring values with an unsigned int. */
+	if (cmrc->up_scale > UINT_MAX) {
+		pr_warn(FW_BUG "Insane CMRC up_scale value 0x%llx\n", cmrc->up_scale);
+		return -EIO;
+	}
+
+	domain_info->base[ERDT_MMIO_CMRC_BASE] =
+		erdt_ioremap(cmrc->cmt_reg_base, cmrc->cmt_reg_size, "CMRC base");
+	if (!domain_info->base[ERDT_MMIO_CMRC_BASE])
+		return -EIO;
+
+	domain_info->cmrc = kmemdup(cmrc, cmrc->header.length, GFP_KERNEL);
+	if (!domain_info->cmrc) {
+		iounmap(domain_info->base[ERDT_MMIO_CMRC_BASE]);
+		domain_info->base[ERDT_MMIO_CMRC_BASE] = NULL;
+		return -ENOMEM;
+	}
+
+	erdt_scale = max(erdt_scale, cmrc->up_scale);
+
+	return 0;
+}
+
 static inline struct acpi_subtbl_hdr_16 *rmdd_subtbl(struct acpi_erdt_rmdd *rmdd)
 {
 	return (void *)rmdd + sizeof(*rmdd);
@@ -170,6 +230,19 @@ static __init bool parse_rmdd_table(struct acpi_subtbl_hdr_16 *rmdd_hdr)
 
 			subtbl_mask |= BIT(ACPI_ERDT_TYPE_CACD);
 			break;
+		case ACPI_ERDT_TYPE_CMRC:
+			/*
+			 * Only one CMRC is supported per domain as there is no
+			 * method to distinguish different CMRCs within a domain.
+			 */
+			if (subtbl_mask & BIT(ACPI_ERDT_TYPE_CMRC))
+				break;
+
+			if (cmrc_init(subtbl, domain_info))
+				goto cleanup;
+
+			subtbl_mask |= BIT(ACPI_ERDT_TYPE_CMRC);
+			break;
 		default:
 			break;
 		}
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index dac1d7e71c0d..160174c25792 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -24,10 +24,12 @@
 /*
  * Index into erdt_domain_info::base[] for each MMIO region.
  * @ERDT_MMIO_RMDD_CREG: RMDD control register base address
+ * @ERDT_MMIO_CMRC_BASE: CMRC monitoring register base address
  */
 enum erdt_mmio_type {
 	ERDT_MMIO_RMDD_CREG,
-	ERDT_MMIO_LAST = ERDT_MMIO_RMDD_CREG
+	ERDT_MMIO_CMRC_BASE,
+	ERDT_MMIO_LAST = ERDT_MMIO_CMRC_BASE
 };
 
 #define ERDT_MMIO_NUM_TYPES	(ERDT_MMIO_LAST + 1)
@@ -35,6 +37,7 @@ enum erdt_mmio_type {
 /**
  * struct erdt_domain_info - Per-domain ERDT information
  * @base:	Array of ioremapped MMIO region base addresses, indexed by ERDT_MMIO_*
+ * @cmrc:	Copy of the ACPI CMRC sub-table for this domain
  * @cpu_mask:	CPUs belonging to this resource management domain
  * @max_rmid:	Maximum RMID supported by this domain
  * @dom_id:	L3 cache ID shared by all CPUs in this domain (-1 if unset)
@@ -42,6 +45,7 @@ enum erdt_mmio_type {
  */
 struct erdt_domain_info {
 	void __iomem		*base[ERDT_MMIO_NUM_TYPES];
+	struct acpi_erdt_cmrc	*cmrc;
 	struct cpumask		cpu_mask;
 	u32			max_rmid;
 	int			dom_id;
-- 
2.25.1