arm_mpam: Reset MSC controls from cpuhp callbacks

When a CPU comes online, it may bring a newly accessible MSC with
it. Only the default partid has its value reset by hardware, and
even then the MSC might not have been reset since its config was
previously dirtied. e.g. Kexec.

Any in-use partid must have its configuration restored, or reset.
In-use partids may be held in caches and evicted later.

MSC are also reset when CPUs are taken offline to cover cases where
firmware doesn't reset the MSC over reboot using UEFI, or kexec
where there is no firmware involvement.

If the configuration for a RIS has not been touched since it was
brought online, it does not need resetting again.

To reset, write the maximum values for all discovered controls.

CC: Rohit Mathew <Rohit.Mathew@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Tested-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com>
Tested-by: Gavin Shan <gshan@redhat.com>
Tested-by: Zeng Heng <zengheng4@huawei.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index f9ac88bf06b70f8f2f5d9f3dfbf006e8cc436b49..4bd4d57a3baaab2422e4eddedcdd7e17b8a58644 100644 (file)
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -7,6 +7,7 @@
 #include <linux/atomic.h>
 #include <linux/arm_mpam.h>
 #include <linux/bitfield.h>
+#include <linux/bitmap.h>
 #include <linux/cacheinfo.h>
 #include <linux/cpu.h>
 #include <linux/cpumask.h>
@@ -752,8 +753,104 @@ static int mpam_msc_hw_probe(struct mpam_msc *msc)
        return 0;
 }
 
+static void mpam_reset_msc_bitmap(struct mpam_msc *msc, u16 reg, u16 wd)
+{
+       u32 num_words, msb;
+       u32 bm = ~0;
+       int i;
+
+       lockdep_assert_held(&msc->part_sel_lock);
+
+       if (wd == 0)
+               return;
+
+       /*
+        * Write all ~0 to all but the last 32bit-word, which may
+        * have fewer bits...
+        */
+       num_words = DIV_ROUND_UP(wd, 32);
+       for (i = 0; i < num_words - 1; i++, reg += sizeof(bm))
+               __mpam_write_reg(msc, reg, bm);
+
+       /*
+        * ....and then the last (maybe) partial 32bit word. When wd is a
+        * multiple of 32, msb should be 31 to write a full 32bit word.
+        */
+       msb = (wd - 1) % 32;
+       bm = GENMASK(msb, 0);
+       __mpam_write_reg(msc, reg, bm);
+}
+
+static void mpam_reset_ris_partid(struct mpam_msc_ris *ris, u16 partid)
+{
+       struct mpam_msc *msc = ris->vmsc->msc;
+       struct mpam_props *rprops = &ris->props;
+
+       WARN_ON_ONCE(!srcu_read_lock_held((&mpam_srcu)));
+
+       mutex_lock(&msc->part_sel_lock);
+       __mpam_part_sel(ris->ris_idx, partid, msc);
+
+       if (mpam_has_feature(mpam_feat_cpor_part, rprops))
+               mpam_reset_msc_bitmap(msc, MPAMCFG_CPBM, rprops->cpbm_wd);
+
+       if (mpam_has_feature(mpam_feat_mbw_part, rprops))
+               mpam_reset_msc_bitmap(msc, MPAMCFG_MBW_PBM, rprops->mbw_pbm_bits);
+
+       if (mpam_has_feature(mpam_feat_mbw_min, rprops))
+               mpam_write_partsel_reg(msc, MBW_MIN, 0);
+
+       if (mpam_has_feature(mpam_feat_mbw_max, rprops))
+               mpam_write_partsel_reg(msc, MBW_MAX, MPAMCFG_MBW_MAX_MAX);
+
+       mutex_unlock(&msc->part_sel_lock);
+}
+
+static void mpam_reset_ris(struct mpam_msc_ris *ris)
+{
+       u16 partid, partid_max;
+
+       WARN_ON_ONCE(!srcu_read_lock_held((&mpam_srcu)));
+
+       if (ris->in_reset_state)
+               return;
+
+       spin_lock(&partid_max_lock);
+       partid_max = mpam_partid_max;
+       spin_unlock(&partid_max_lock);
+       for (partid = 0; partid <= partid_max; partid++)
+               mpam_reset_ris_partid(ris, partid);
+}
+
+static void mpam_reset_msc(struct mpam_msc *msc, bool online)
+{
+       struct mpam_msc_ris *ris;
+
+       list_for_each_entry_srcu(ris, &msc->ris, msc_list, srcu_read_lock_held(&mpam_srcu)) {
+               mpam_reset_ris(ris);
+
+               /*
+                * Set in_reset_state when coming online. The reset state
+                * for non-zero partid may be lost while the CPUs are offline.
+                */
+               ris->in_reset_state = online;
+       }
+}
+
 static int mpam_cpu_online(unsigned int cpu)
 {
+       struct mpam_msc *msc;
+
+       guard(srcu)(&mpam_srcu);
+       list_for_each_entry_srcu(msc, &mpam_all_msc, all_msc_list,
+                                srcu_read_lock_held(&mpam_srcu)) {
+               if (!cpumask_test_cpu(cpu, &msc->accessibility))
+                       continue;
+
+               if (atomic_fetch_inc(&msc->online_refs) == 0)
+                       mpam_reset_msc(msc, true);
+       }
+
        return 0;
 }
 
@@ -792,6 +889,18 @@ static int mpam_discovery_cpu_online(unsigned int cpu)
 
 static int mpam_cpu_offline(unsigned int cpu)
 {
+       struct mpam_msc *msc;
+
+       guard(srcu)(&mpam_srcu);
+       list_for_each_entry_srcu(msc, &mpam_all_msc, all_msc_list,
+                                srcu_read_lock_held(&mpam_srcu)) {
+               if (!cpumask_test_cpu(cpu, &msc->accessibility))
+                       continue;
+
+               if (atomic_dec_and_test(&msc->online_refs))
+                       mpam_reset_msc(msc, false);
+       }
+
        return 0;
 }
 

diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index 4749ac223adcf6621ac6abea66ff08b7e595e773..dec485cd8a912f81931cda070e04dec1b5100c26 100644 (file)
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -5,6 +5,7 @@
 #define MPAM_INTERNAL_H
 
 #include <linux/arm_mpam.h>
+#include <linux/atomic.h>
 #include <linux/bitmap.h>
 #include <linux/cpumask.h>
 #include <linux/io.h>
@@ -45,6 +46,7 @@ struct mpam_msc {
        enum mpam_msc_iface     iface;
        u32                     nrdy_usec;
        cpumask_t               accessibility;
+       atomic_t                online_refs;
 
        /*
         * probe_lock is only taken during discovery. After discovery these
@@ -198,6 +200,7 @@ struct mpam_msc_ris {
        u8                      ris_idx;
        u64                     idr;
        struct mpam_props       props;
+       bool                    in_reset_state;
 
        cpumask_t               affinity;