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Subject[PATCH 04/32] x86/intel_rdt: Add L3 cache capacity bitmask management
Date
From: Vikas Shivappa <vikas.shivappa@linux.intel.com>

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@linux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/include/asm/intel_rdt.h | 4 ++
arch/x86/kernel/cpu/intel_rdt.c | 133 ++++++++++++++++++++++++++++++++++++++-
2 files changed, 136 insertions(+), 1 deletion(-)

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 d79213a..6ad5b48 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -34,8 +34,22 @@ 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);

+struct rdt_remote_data {
+ int msr;
+ u64 val;
+};
+
static inline void closid_get(u32 closid)
{
struct clos_cbm_table *cct = &cctable[closid];
@@ -82,11 +96,126 @@ 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 msr_cpu_update(void *arg)
+{
+ struct rdt_remote_data *info = arg;
+
+ wrmsrl(info->msr, info->val);
+}
+
+/*
+ * msr_update_all() - Update the msr for all packages.
+ */
+static inline void msr_update_all(int msr, u64 val)
+{
+ struct rdt_remote_data info;
+
+ info.msr = msr;
+ info.val = val;
+ on_each_cpu_mask(&rdt_cpumask, msr_cpu_update, &info, 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;
u32 maxid, max_cbm_len;
- int err = 0, size;
+ int err = 0, size, i;

if (!cpu_has(c, X86_FEATURE_CAT_L3))
return -ENODEV;
@@ -109,6 +238,8 @@ 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:

--
2.5.0
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