6 files changed, 184 insertions, 105 deletions

diff --git a/drivers/misc/sgi-gru/gruhandles.c b/drivers/misc/sgi-gru/gruhandles.c
index a3a870ad9153..37e7cfc53b9c 100644
--- a/drivers/misc/sgi-gru/gruhandles.c
+++ b/drivers/misc/sgi-gru/gruhandles.c
@@ -57,7 +57,7 @@ static void start_instruction(void *h)
 static int wait_instruction_complete(void *h, enum mcs_op opc)
 {
         int status;
-        cycles_t start_time = get_cycles();
+        unsigned long start_time = get_cycles();
 
         while (1) {
                 cpu_relax();
@@ -65,7 +65,8 @@ static int wait_instruction_complete(void *h, enum mcs_op opc)
                 if (status != CCHSTATUS_ACTIVE)
                         break;
                 if (GRU_OPERATION_TIMEOUT < (get_cycles() - start_time))
-                        panic("GRU %p is malfunctioning\n", h);
+                        panic("GRU %p is malfunctioning: start %ld, end %ld\n",
+                              h, start_time, (unsigned long)get_cycles());
         }
         if (gru_options & OPT_STATS)
                 update_mcs_stats(opc, get_cycles() - start_time);
diff --git a/drivers/misc/sgi-gru/grukdump.c b/drivers/misc/sgi-gru/grukdump.c
index 27e00931a7b8..7b1bdf3906ba 100644
--- a/drivers/misc/sgi-gru/grukdump.c
+++ b/drivers/misc/sgi-gru/grukdump.c
@@ -131,7 +131,7 @@ static int gru_dump_context(struct gru_state *gru, int ctxnum,
 
         if (cch_locked || !lock_cch) {
                 gts = gru->gs_gts[ctxnum];
-                if (gts) {
+                if (gts && gts->ts_vma) {
                         hdr.pid = gts->ts_tgid_owner;
                         hdr.vaddr = gts->ts_vma->vm_start;
                 }
diff --git a/drivers/misc/sgi-gru/grukservices.c b/drivers/misc/sgi-gru/grukservices.c
index 900f7aad2286..50b4dd8b0c9f 100644
--- a/drivers/misc/sgi-gru/grukservices.c
+++ b/drivers/misc/sgi-gru/grukservices.c
@@ -31,6 +31,7 @@
 #include <linux/proc_fs.h>
 #include <linux/interrupt.h>
 #include <linux/uaccess.h>
+#include <linux/delay.h>
 #include "gru.h"
 #include "grulib.h"
 #include "grutables.h"
@@ -45,18 +46,17 @@
  * resources. This will likely be replaced when we better understand the
  * kernel/user requirements.
  *
- * At boot time, the kernel permanently reserves a fixed number of
- * CBRs/DSRs for each cpu to use. The resources are all taken from
- * the GRU chiplet 1 on the blade. This leaves the full set of resources
- * of chiplet 0 available to be allocated to a single user.
+ * Blade percpu resources reserved for kernel use. These resources are
+ * reserved whenever the the kernel context for the blade is loaded. Note
+ * that the kernel context is not guaranteed to be always available. It is
+ * loaded on demand & can be stolen by a user if the user demand exceeds the
+ * kernel demand. The kernel can always reload the kernel context but
+ * a SLEEP may be required!!!.
  */
-
-/* Blade percpu resources PERMANENTLY reserved for kernel use */
 #define GRU_NUM_KERNEL_CBR      1
 #define GRU_NUM_KERNEL_DSR_BYTES 256
 #define GRU_NUM_KERNEL_DSR_CL   (GRU_NUM_KERNEL_DSR_BYTES /             \
                                         GRU_CACHE_LINE_BYTES)
-#define KERNEL_CTXNUM           15
 
 /* GRU instruction attributes for all instructions */
 #define IMA                     IMA_CB_DELAY
@@ -98,6 +98,88 @@ struct message_header {
 
 #define HSTATUS(mq, h)  ((mq) + offsetof(struct message_queue, hstatus[h]))
 
+/*
+ * Allocate a kernel context (GTS) for the specified blade.
+ *      - protected by writelock on bs_kgts_sema.
+ */
+static void gru_alloc_kernel_context(struct gru_blade_state *bs, int blade_id)
+{
+        int cbr_au_count, dsr_au_count, ncpus;
+
+        ncpus = uv_blade_nr_possible_cpus(blade_id);
+        cbr_au_count = GRU_CB_COUNT_TO_AU(GRU_NUM_KERNEL_CBR * ncpus);
+        dsr_au_count = GRU_DS_BYTES_TO_AU(GRU_NUM_KERNEL_DSR_BYTES * ncpus);
+        bs->bs_kgts = gru_alloc_gts(NULL, cbr_au_count, dsr_au_count, 0, 0);
+}
+
+/*
+ * Reload the blade's kernel context into a GRU chiplet. Called holding
+ * the bs_kgts_sema for READ. Will steal user contexts if necessary.
+ */
+static void gru_load_kernel_context(struct gru_blade_state *bs, int blade_id)
+{
+        struct gru_state *gru;
+        struct gru_thread_state *kgts;
+        void *vaddr;
+        int ctxnum;
+
+        up_read(&bs->bs_kgts_sema);
+        down_write(&bs->bs_kgts_sema);
+
+        if (!bs->bs_kgts)
+                gru_alloc_kernel_context(bs, blade_id);
+        kgts = bs->bs_kgts;
+
+        if (!kgts->ts_gru) {
+                STAT(load_kernel_context);
+                while (!gru_assign_gru_context(kgts, blade_id)) {
+                        msleep(1);
+                        gru_steal_context(kgts, blade_id);
+                }
+                gru_load_context(kgts);
+                gru = bs->bs_kgts->ts_gru;
+                vaddr = gru->gs_gru_base_vaddr;
+                ctxnum = kgts->ts_ctxnum;
+                bs->kernel_cb = get_gseg_base_address_cb(vaddr, ctxnum, 0);
+                bs->kernel_dsr = get_gseg_base_address_ds(vaddr, ctxnum, 0);
+        }
+        downgrade_write(&bs->bs_kgts_sema);
+}
+
+/*
+ * Lock & load the kernel context for the specified blade.
+ */
+static struct gru_blade_state *gru_lock_kernel_context(int blade_id)
+{
+        struct gru_blade_state *bs;
+
+        STAT(lock_kernel_context);
+        bs = gru_base[blade_id];
+
+        down_read(&bs->bs_kgts_sema);
+        if (!bs->bs_kgts || !bs->bs_kgts->ts_gru)
+                gru_load_kernel_context(bs, blade_id);
+        return bs;
+
+}
+
+/*
+ * Unlock the kernel context for the specified blade. Context is not
+ * unloaded but may be stolen before next use.
+ */
+static void gru_unlock_kernel_context(int blade_id)
+{
+        struct gru_blade_state *bs;
+
+        bs = gru_base[blade_id];
+        up_read(&bs->bs_kgts_sema);
+        STAT(unlock_kernel_context);
+}
+
+/*
+ * Reserve & get pointers to the DSR/CBRs reserved for the current cpu.
+ *      - returns with preemption disabled
+ */
 static int gru_get_cpu_resources(int dsr_bytes, void **cb, void **dsr)
 {
         struct gru_blade_state *bs;
@@ -105,18 +187,23 @@ static int gru_get_cpu_resources(int dsr_bytes, void **cb, void **dsr)
 
         BUG_ON(dsr_bytes > GRU_NUM_KERNEL_DSR_BYTES);
         preempt_disable();
-        bs = gru_base[uv_numa_blade_id()];
+        bs = gru_lock_kernel_context(uv_numa_blade_id());
         lcpu = uv_blade_processor_id();
         *cb = bs->kernel_cb + lcpu * GRU_HANDLE_STRIDE;
         *dsr = bs->kernel_dsr + lcpu * GRU_NUM_KERNEL_DSR_BYTES;
         return 0;
 }
 
+/*
+ * Free the current cpus reserved DSR/CBR resources.
+ */
 static void gru_free_cpu_resources(void *cb, void *dsr)
 {
+        gru_unlock_kernel_context(uv_numa_blade_id());
         preempt_enable();
 }
 
+/*----------------------------------------------------------------------*/
 int gru_get_cb_exception_detail(void *cb,
                 struct control_block_extended_exc_detail *excdet)
 {
@@ -597,34 +684,36 @@ EXPORT_SYMBOL_GPL(gru_copy_gpa);
 
 /* ------------------- KERNEL QUICKTESTS RUN AT STARTUP ----------------*/
 /*      Temp - will delete after we gain confidence in the GRU          */
-static __cacheline_aligned unsigned long word0;
-static __cacheline_aligned unsigned long word1;
 
-static int quicktest(struct gru_state *gru)
+int quicktest(void)
 {
+        unsigned long word0;
+        unsigned long word1;
         void *cb;
-        void *ds;
+        void *dsr;
         unsigned long *p;
 
-        cb = get_gseg_base_address_cb(gru->gs_gru_base_vaddr, KERNEL_CTXNUM, 0);
-        ds = get_gseg_base_address_ds(gru->gs_gru_base_vaddr, KERNEL_CTXNUM, 0);
-        p = ds;
+        if (gru_get_cpu_resources(GRU_CACHE_LINE_BYTES, &cb, &dsr))
+                return MQE_BUG_NO_RESOURCES;
+        p = dsr;
         word0 = MAGIC;
+        word1 = 0;
 
-        gru_vload(cb, uv_gpa(&word0), 0, XTYPE_DW, 1, 1, IMA);
+        gru_vload(cb, uv_gpa(&word0), gru_get_tri(dsr), XTYPE_DW, 1, 1, IMA);
         if (gru_wait(cb) != CBS_IDLE)
                 BUG();
 
-        if (*(unsigned long *)ds != MAGIC)
+        if (*p != MAGIC)
                 BUG();
-        gru_vstore(cb, uv_gpa(&word1), 0, XTYPE_DW, 1, 1, IMA);
+        gru_vstore(cb, uv_gpa(&word1), gru_get_tri(dsr), XTYPE_DW, 1, 1, IMA);
         if (gru_wait(cb) != CBS_IDLE)
                 BUG();
+        gru_free_cpu_resources(cb, dsr);
 
-        if (word0 != word1 || word0 != MAGIC) {
+        if (word0 != word1 || word1 != MAGIC) {
                 printk
-                    ("GRU quicktest err: gid %d, found 0x%lx, expected 0x%lx\n",
-                     gru->gs_gid, word1, MAGIC);
+                    ("GRU quicktest err: found 0x%lx, expected 0x%lx\n",
+                     word1, MAGIC);
                 BUG();          /* ZZZ should not be fatal */
         }
 
@@ -635,80 +724,30 @@ static int quicktest(struct gru_state *gru)
 int gru_kservices_init(struct gru_state *gru)
 {
         struct gru_blade_state *bs;
-        struct gru_context_configuration_handle *cch;
-        unsigned long cbr_map, dsr_map;
-        int err, num, cpus_possible;
-
-        /*
-         * Currently, resources are reserved ONLY on the second chiplet
-         * on each blade. This leaves ALL resources on chiplet 0 available
-         * for user code.
-         */
+
         bs = gru->gs_blade;
-        if (gru != &bs->bs_grus[1])
+        if (gru != &bs->bs_grus[0])
                 return 0;
 
-        cpus_possible = uv_blade_nr_possible_cpus(gru->gs_blade_id);
-
-        num = GRU_NUM_KERNEL_CBR * cpus_possible;
-        cbr_map = gru_reserve_cb_resources(gru, GRU_CB_COUNT_TO_AU(num), NULL);
-        gru->gs_reserved_cbrs += num;
-
-        num = GRU_NUM_KERNEL_DSR_BYTES * cpus_possible;
-        dsr_map = gru_reserve_ds_resources(gru, GRU_DS_BYTES_TO_AU(num), NULL);
-        gru->gs_reserved_dsr_bytes += num;
-
-        gru->gs_active_contexts++;
-        __set_bit(KERNEL_CTXNUM, &gru->gs_context_map);
-        cch = get_cch(gru->gs_gru_base_vaddr, KERNEL_CTXNUM);
-
-        bs->kernel_cb = get_gseg_base_address_cb(gru->gs_gru_base_vaddr,
-                                        KERNEL_CTXNUM, 0);
-        bs->kernel_dsr = get_gseg_base_address_ds(gru->gs_gru_base_vaddr,
-                                        KERNEL_CTXNUM, 0);
-
-        lock_cch_handle(cch);
-        cch->tfm_fault_bit_enable = 0;
-        cch->tlb_int_enable = 0;
-        cch->tfm_done_bit_enable = 0;
-        cch->unmap_enable = 1;
-        cch->dsr_allocation_map = dsr_map;
-        cch->cbr_allocation_map = cbr_map;
-
-        err = cch_allocate(cch);
-        if (err) {
-                gru_dbg(grudev,
-                        "Unable to allocate kernel CCH: gid %d, err %d\n",
-                        gru->gs_gid, err);
-                BUG();
-        }
-        if (cch_start(cch)) {
-                gru_dbg(grudev, "Unable to start kernel CCH: gid %d, err %d\n",
-                        gru->gs_gid, err);
-                BUG();
-        }
-        unlock_cch_handle(cch);
+        init_rwsem(&bs->bs_kgts_sema);
 
         if (gru_options & GRU_QUICKLOOK)
-                quicktest(gru);
+                quicktest();
         return 0;
 }
 
 void gru_kservices_exit(struct gru_state *gru)
 {
-        struct gru_context_configuration_handle *cch;
         struct gru_blade_state *bs;
+        struct gru_thread_state *kgts;
 
         bs = gru->gs_blade;
-        if (gru != &bs->bs_grus[1])
+        if (gru != &bs->bs_grus[0])
                 return;
 
-        cch = get_cch(gru->gs_gru_base_vaddr, KERNEL_CTXNUM);
-        lock_cch_handle(cch);
-        if (cch_interrupt_sync(cch))
-                BUG();
-        if (cch_deallocate(cch))
-                BUG();
-        unlock_cch_handle(cch);
+        kgts = bs->bs_kgts;
+        if (kgts && kgts->ts_gru)
+                gru_unload_context(kgts, 0);
+        kfree(kgts);
 }
 
diff --git a/drivers/misc/sgi-gru/grumain.c b/drivers/misc/sgi-gru/grumain.c
index 0c7bd384f0cf..3398e54a762b 100644
--- a/drivers/misc/sgi-gru/grumain.c
+++ b/drivers/misc/sgi-gru/grumain.c
@@ -96,7 +96,7 @@ static int gru_reset_asid_limit(struct gru_state *gru, int asid)
         gid = gru->gs_gid;
 again:
         for (i = 0; i < GRU_NUM_CCH; i++) {
-                if (!gru->gs_gts[i])
+                if (!gru->gs_gts[i] || is_kernel_context(gru->gs_gts[i]))
                         continue;
                 inuse_asid = gru->gs_gts[i]->ts_gms->ms_asids[gid].mt_asid;
                 gru_dbg(grudev, "gid %d, gts %p, gms %p, inuse 0x%x, cxt %d\n",
@@ -506,7 +506,8 @@ void gru_unload_context(struct gru_thread_state *gts, int savestate)
         struct gru_context_configuration_handle *cch;
         int ctxnum = gts->ts_ctxnum;
 
-        zap_vma_ptes(gts->ts_vma, UGRUADDR(gts), GRU_GSEG_PAGESIZE);
+        if (!is_kernel_context(gts))
+                zap_vma_ptes(gts->ts_vma, UGRUADDR(gts), GRU_GSEG_PAGESIZE);
         cch = get_cch(gru->gs_gru_base_vaddr, ctxnum);
 
         gru_dbg(grudev, "gts %p\n", gts);
@@ -514,7 +515,8 @@ void gru_unload_context(struct gru_thread_state *gts, int savestate)
         if (cch_interrupt_sync(cch))
                 BUG();
 
-        gru_unload_mm_tracker(gru, gts);
+        if (!is_kernel_context(gts))
+                gru_unload_mm_tracker(gru, gts);
         if (savestate)
                 gru_unload_context_data(gts->ts_gdata, gru->gs_gru_base_vaddr,
                                         ctxnum, gts->ts_cbr_map,
@@ -526,7 +528,6 @@ void gru_unload_context(struct gru_thread_state *gts, int savestate)
         unlock_cch_handle(cch);
 
         gru_free_gru_context(gts);
-        STAT(unload_context);
 }
 
 /*
@@ -554,11 +555,16 @@ void gru_load_context(struct gru_thread_state *gts)
         cch->tfm_done_bit_enable = 0;
         cch->dsr_allocation_map = gts->ts_dsr_map;
         cch->cbr_allocation_map = gts->ts_cbr_map;
-        asid = gru_load_mm_tracker(gru, gts);
-        cch->unmap_enable = 0;
-        for (i = 0; i < 8; i++) {
-                cch->asid[i] = asid + i;
-                cch->sizeavail[i] = gts->ts_sizeavail;
+
+        if (is_kernel_context(gts)) {
+                cch->unmap_enable = 1;
+        } else {
+                cch->unmap_enable = 0;
+                asid = gru_load_mm_tracker(gru, gts);
+                for (i = 0; i < 8; i++) {
+                        cch->asid[i] = asid + i;
+                        cch->sizeavail[i] = gts->ts_sizeavail;
+                }
         }
 
         err = cch_allocate(cch);
@@ -575,8 +581,6 @@ void gru_load_context(struct gru_thread_state *gts)
         if (cch_start(cch))
                 BUG();
         unlock_cch_handle(cch);
-
-        STAT(load_context);
 }
 
 /*
@@ -652,6 +656,27 @@ static int gru_retarget_intr(struct gru_thread_state *gts)
 #define next_gru(b, g)  (((g) < &(b)->bs_grus[GRU_CHIPLETS_PER_BLADE - 1]) ?  \
                                  ((g)+1) : &(b)->bs_grus[0])
 
+static int is_gts_stealable(struct gru_thread_state *gts,
+                struct gru_blade_state *bs)
+{
+        if (is_kernel_context(gts))
+                return down_write_trylock(&bs->bs_kgts_sema);
+        else
+                return mutex_trylock(&gts->ts_ctxlock);
+}
+
+static void gts_stolen(struct gru_thread_state *gts,
+                struct gru_blade_state *bs)
+{
+        if (is_kernel_context(gts)) {
+                up_write(&bs->bs_kgts_sema);
+                STAT(steal_kernel_context);
+        } else {
+                mutex_unlock(&gts->ts_ctxlock);
+                STAT(steal_user_context);
+        }
+}
+
 void gru_steal_context(struct gru_thread_state *gts, int blade_id)
 {
         struct gru_blade_state *blade;
@@ -685,7 +710,7 @@ void gru_steal_context(struct gru_thread_state *gts, int blade_id)
                          * success are high. If trylock fails, try to steal a
                          * different GSEG.
                          */
-                        if (ngts && mutex_trylock(&ngts->ts_ctxlock))
+                        if (ngts && is_gts_stealable(ngts, blade))
                                 break;
                         ngts = NULL;
                         flag = 1;
@@ -701,10 +726,9 @@ void gru_steal_context(struct gru_thread_state *gts, int blade_id)
         spin_unlock(&blade->bs_lock);
 
         if (ngts) {
-                STAT(steal_context);
                 ngts->ts_steal_jiffies = jiffies;
-                gru_unload_context(ngts, 1);
-                mutex_unlock(&ngts->ts_ctxlock);
+                gru_unload_context(ngts, is_kernel_context(ngts) ? 0 : 1);
+                gts_stolen(ngts, blade);
         } else {
                 STAT(steal_context_failed);
         }
@@ -810,6 +834,7 @@ again:
         }
 
         if (!gts->ts_gru) {
+                STAT(load_user_context);
                 if (!gru_assign_gru_context(gts, blade_id)) {
                         preempt_enable();
                         mutex_unlock(&gts->ts_ctxlock);
diff --git a/drivers/misc/sgi-gru/gruprocfs.c b/drivers/misc/sgi-gru/gruprocfs.c
index c46c1c5f0c73..6ef4cb4b84c8 100644
--- a/drivers/misc/sgi-gru/gruprocfs.c
+++ b/drivers/misc/sgi-gru/gruprocfs.c
@@ -51,9 +51,12 @@ static int statistics_show(struct seq_file *s, void *p)
         printstat(s, assign_context);
         printstat(s, assign_context_failed);
         printstat(s, free_context);
-        printstat(s, load_context);
-        printstat(s, unload_context);
-        printstat(s, steal_context);
+        printstat(s, load_user_context);
+        printstat(s, load_kernel_context);
+        printstat(s, lock_kernel_context);
+        printstat(s, unlock_kernel_context);
+        printstat(s, steal_user_context);
+        printstat(s, steal_kernel_context);
         printstat(s, steal_context_failed);
         printstat(s, nopfn);
         printstat(s, break_cow);
diff --git a/drivers/misc/sgi-gru/grutables.h b/drivers/misc/sgi-gru/grutables.h
index 4ddb5b92acbb..1c85fdcf5d37 100644
--- a/drivers/misc/sgi-gru/grutables.h
+++ b/drivers/misc/sgi-gru/grutables.h
@@ -174,9 +174,12 @@ struct gru_stats_s {
         atomic_long_t assign_context;
         atomic_long_t assign_context_failed;
         atomic_long_t free_context;
-        atomic_long_t load_context;
-        atomic_long_t unload_context;
-        atomic_long_t steal_context;
+        atomic_long_t load_user_context;
+        atomic_long_t load_kernel_context;
+        atomic_long_t lock_kernel_context;
+        atomic_long_t unlock_kernel_context;
+        atomic_long_t steal_user_context;
+        atomic_long_t steal_kernel_context;
         atomic_long_t steal_context_failed;
         atomic_long_t nopfn;
         atomic_long_t break_cow;
@@ -454,6 +457,9 @@ struct gru_blade_state {
                                                            reserved cb */
         void                    *kernel_dsr;            /* First kernel
                                                            reserved DSR */
+        struct rw_semaphore     bs_kgts_sema;           /* lock for kgts */
+        struct gru_thread_state *bs_kgts;               /* GTS for kernel use */
+
         /* ---- the following are protected by the bs_lock spinlock ---- */
         spinlock_t              bs_lock;                /* lock used for
                                                            stealing contexts */
@@ -597,6 +603,11 @@ static inline void unlock_tgh_handle(struct gru_tlb_global_handle *tgh)
         __unlock_handle(tgh);
 }
 
+static inline int is_kernel_context(struct gru_thread_state *gts)
+{
+        return !gts->ts_mm;
+}
+
 /*-----------------------------------------------------------------------------
  * Function prototypes & externs
  */