[PATCH 06/11] x86/intel_rdt: Add L3 cache capacity bitmask management

[Vikas Shivappa]

This patch adds different APIs to manage the L3 cache capacity bitmask.
The capacity bit mask(CBM) needs to have only contiguous bits set. The
current implementation has a global CBM for each class of service id.
There are APIs added to update the CBM via MSR write to IA32_L3_MASK_n
on all packages. Other APIs are to read and write entries to the
clos_cbm_table.

Signed-off-by: Vikas Shivappa <vikas.shivappa@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/intel_rdt.h |   4 ++
 arch/x86/kernel/cpu/intel_rdt.c  | 122 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 126 insertions(+)

diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h
index 88b7643..4f45dc8 100644
--- a/arch/x86/include/asm/intel_rdt.h
+++ b/arch/x86/include/asm/intel_rdt.h
@@ -3,6 +3,10 @@
 
 #ifdef CONFIG_INTEL_RDT
 
+#define MAX_CBM_LENGTH			32
+#define IA32_L3_CBM_BASE		0xc90
+#define CBM_FROM_INDEX(x)		(IA32_L3_CBM_BASE + x)
+
 struct clos_cbm_table {
 	unsigned long l3_cbm;
 	unsigned int clos_refcnt;
diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index cc988b1..c9db0ed 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -34,6 +34,15 @@ static struct clos_cbm_table *cctable;
  * closid availability bit map.
  */
 unsigned long *closmap;
+/*
+ * Mask of CPUs for writing CBM values. We only need one CPU per-socket.
+ */
+static cpumask_t rdt_cpumask;
+/*
+ * Temporary cpumask used during hot cpu notificaiton handling. The usage
+ * is serialized by hot cpu locks.
+ */
+static cpumask_t tmp_cpumask;
 static DEFINE_MUTEX(rdt_group_mutex);
 
 static inline void closid_get(u32 closid)
@@ -82,6 +91,117 @@ static void closid_put(u32 closid)
 		closid_free(closid);
 }
 
+static bool cbm_validate(unsigned long var)
+{
+	u32 max_cbm_len = boot_cpu_data.x86_cache_max_cbm_len;
+	unsigned long first_bit, zero_bit;
+	u64 max_cbm;
+
+	if (bitmap_weight(&var, max_cbm_len) < 1)
+		return false;
+
+	max_cbm = (1ULL << max_cbm_len) - 1;
+	if (var & ~max_cbm)
+		return false;
+
+	first_bit = find_first_bit(&var, max_cbm_len);
+	zero_bit = find_next_zero_bit(&var, max_cbm_len, first_bit);
+
+	if (find_next_bit(&var, max_cbm_len, zero_bit) < max_cbm_len)
+		return false;
+
+	return true;
+}
+
+static int clos_cbm_table_read(u32 closid, unsigned long *l3_cbm)
+{
+	u32 maxid = boot_cpu_data.x86_cache_max_closid;
+
+	lockdep_assert_held(&rdt_group_mutex);
+
+	if (closid >= maxid)
+		return -EINVAL;
+
+	*l3_cbm = cctable[closid].l3_cbm;
+
+	return 0;
+}
+
+/*
+ * clos_cbm_table_update() - Update a clos cbm table entry.
+ * @closid: the closid whose cbm needs to be updated
+ * @cbm: the new cbm value that has to be updated
+ *
+ * This assumes the cbm is validated as per the interface requirements
+ * and the cache allocation requirements(through the cbm_validate).
+ */
+static int clos_cbm_table_update(u32 closid, unsigned long cbm)
+{
+	u32 maxid = boot_cpu_data.x86_cache_max_closid;
+
+	lockdep_assert_held(&rdt_group_mutex);
+
+	if (closid >= maxid)
+		return -EINVAL;
+
+	cctable[closid].l3_cbm = cbm;
+
+	return 0;
+}
+
+static bool cbm_search(unsigned long cbm, u32 *closid)
+{
+	u32 maxid = boot_cpu_data.x86_cache_max_closid;
+	u32 i;
+
+	for (i = 0; i < maxid; i++) {
+		if (cctable[i].clos_refcnt &&
+		    bitmap_equal(&cbm, &cctable[i].l3_cbm, MAX_CBM_LENGTH)) {
+			*closid = i;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static void closcbm_map_dump(void)
+{
+	u32 i;
+
+	pr_debug("CBMMAP\n");
+	for (i = 0; i < boot_cpu_data.x86_cache_max_closid; i++) {
+		pr_debug("l3_cbm: 0x%x,clos_refcnt: %u\n",
+		 (unsigned int)cctable[i].l3_cbm, cctable[i].clos_refcnt);
+	}
+}
+
+static void cbm_cpu_update(void *info)
+{
+	u32 closid = (u32) info;
+
+	wrmsrl(CBM_FROM_INDEX(closid), cctable[closid].l3_cbm);
+}
+
+/*
+ * cbm_update_all() - Update the cache bit mask for all packages.
+ */
+static void cbm_update_all(u32 closid)
+{
+	on_each_cpu_mask(&rdt_cpumask, cbm_cpu_update, (void *)closid, 1);
+}
+
+static inline bool rdt_cpumask_update(int cpu)
+{
+	cpumask_and(&tmp_cpumask, &rdt_cpumask, topology_core_cpumask(cpu));
+	if (cpumask_empty(&tmp_cpumask)) {
+		cpumask_set_cpu(cpu, &rdt_cpumask);
+		return true;
+	}
+
+	return false;
+}
+
 static int __init intel_rdt_late_init(void)
 {
 	struct cpuinfo_x86 *c = &boot_cpu_data;
@@ -112,6 +232,8 @@ static int __init intel_rdt_late_init(void)
 		goto out_err;
 	}
 
+	for_each_online_cpu(i)
+		rdt_cpumask_update(i);
 	pr_info("Intel cache allocation enabled\n");
 out_err:
 
-- 
1.9.1

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