#include <linux/seq_file.h>
#include <linux/sched.h>
#include <linux/slab.h>
+#include <linux/cpu.h>
#include <uapi/linux/magic.h>
#include <asm/intel_rdt.h>
+#include <asm/intel_rdt_common.h>
DEFINE_STATIC_KEY_FALSE(rdt_enable_key);
struct kernfs_root *rdt_root;
/* Kernel fs node for "info" directory under root */
static struct kernfs_node *kn_info;
+/*
+ * Trivial allocator for CLOSIDs. Since h/w only supports a small number,
+ * we can keep a bitmap of free CLOSIDs in a single integer.
+ *
+ * Using a global CLOSID across all resources has some advantages and
+ * some drawbacks:
+ * + We can simply set "current->closid" to assign a task to a resource
+ * group.
+ * + Context switch code can avoid extra memory references deciding which
+ * CLOSID to load into the PQR_ASSOC MSR
+ * - We give up some options in configuring resource groups across multi-socket
+ * systems.
+ * - Our choices on how to configure each resource become progressively more
+ * limited as the number of resources grows.
+ */
+static int closid_free_map;
+
+static void closid_init(void)
+{
+ struct rdt_resource *r;
+ int rdt_min_closid = 32;
+
+ /* Compute rdt_min_closid across all resources */
+ for_each_enabled_rdt_resource(r)
+ rdt_min_closid = min(rdt_min_closid, r->num_closid);
+
+ closid_free_map = BIT_MASK(rdt_min_closid) - 1;
+
+ /* CLOSID 0 is always reserved for the default group */
+ closid_free_map &= ~1;
+}
+
+int closid_alloc(void)
+{
+ int closid = ffs(closid_free_map);
+
+ if (closid == 0)
+ return -ENOSPC;
+ closid--;
+ closid_free_map &= ~(1 << closid);
+
+ return closid;
+}
+
+static void closid_free(int closid)
+{
+ closid_free_map |= 1 << closid;
+}
+
/* set uid and gid of rdtgroup dirs and files to that of the creator */
static int rdtgroup_kn_set_ugid(struct kernfs_node *kn)
{
return ret;
}
+/*
+ * We don't allow rdtgroup directories to be created anywhere
+ * except the root directory. Thus when looking for the rdtgroup
+ * structure for a kernfs node we are either looking at a directory,
+ * in which case the rdtgroup structure is pointed at by the "priv"
+ * field, otherwise we have a file, and need only look to the parent
+ * to find the rdtgroup.
+ */
+static struct rdtgroup *kernfs_to_rdtgroup(struct kernfs_node *kn)
+{
+ if (kernfs_type(kn) == KERNFS_DIR)
+ return kn->priv;
+ else
+ return kn->parent->priv;
+}
+
+struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn)
+{
+ struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn);
+
+ atomic_inc(&rdtgrp->waitcount);
+ kernfs_break_active_protection(kn);
+
+ mutex_lock(&rdtgroup_mutex);
+
+ /* Was this group deleted while we waited? */
+ if (rdtgrp->flags & RDT_DELETED)
+ return NULL;
+
+ return rdtgrp;
+}
+
+void rdtgroup_kn_unlock(struct kernfs_node *kn)
+{
+ struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn);
+
+ mutex_unlock(&rdtgroup_mutex);
+
+ if (atomic_dec_and_test(&rdtgrp->waitcount) &&
+ (rdtgrp->flags & RDT_DELETED)) {
+ kernfs_unbreak_active_protection(kn);
+ kernfs_put(kn);
+ kfree(rdtgrp);
+ } else {
+ kernfs_unbreak_active_protection(kn);
+ }
+}
+
static struct dentry *rdt_mount(struct file_system_type *fs_type,
int flags, const char *unused_dev_name,
void *data)
goto out_cdp;
}
+ closid_init();
+
ret = rdtgroup_create_info_dir(rdtgroup_default.kn);
if (ret)
goto out_cdp;
return 0;
}
+/*
+ * MSR_IA32_PQR_ASSOC is scoped per logical CPU, so all updates
+ * are always in thread context.
+ */
+static void rdt_reset_pqr_assoc_closid(void *v)
+{
+ struct intel_pqr_state *state = this_cpu_ptr(&pqr_state);
+
+ state->closid = 0;
+ wrmsr(MSR_IA32_PQR_ASSOC, state->rmid, 0);
+}
+
/*
* Forcibly remove all of subdirectories under root.
*/
static void rmdir_all_sub(void)
{
+ struct rdtgroup *rdtgrp, *tmp;
+
+ get_cpu();
+ /* Reset PQR_ASSOC MSR on this cpu. */
+ rdt_reset_pqr_assoc_closid(NULL);
+ /* Reset PQR_ASSOC MSR on the rest of cpus. */
+ smp_call_function_many(cpu_online_mask, rdt_reset_pqr_assoc_closid,
+ NULL, 1);
+ put_cpu();
+ list_for_each_entry_safe(rdtgrp, tmp, &rdt_all_groups, rdtgroup_list) {
+ /* Remove each rdtgroup other than root */
+ if (rdtgrp == &rdtgroup_default)
+ continue;
+ kernfs_remove(rdtgrp->kn);
+ list_del(&rdtgrp->rdtgroup_list);
+ kfree(rdtgrp);
+ }
kernfs_remove(kn_info);
}
.kill_sb = rdt_kill_sb,
};
+static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
+ umode_t mode)
+{
+ struct rdtgroup *parent, *rdtgrp;
+ struct kernfs_node *kn;
+ int ret, closid;
+
+ /* Only allow mkdir in the root directory */
+ if (parent_kn != rdtgroup_default.kn)
+ return -EPERM;
+
+ /* Do not accept '\n' to avoid unparsable situation. */
+ if (strchr(name, '\n'))
+ return -EINVAL;
+
+ parent = rdtgroup_kn_lock_live(parent_kn);
+ if (!parent) {
+ ret = -ENODEV;
+ goto out_unlock;
+ }
+
+ ret = closid_alloc();
+ if (ret < 0)
+ goto out_unlock;
+ closid = ret;
+
+ /* allocate the rdtgroup. */
+ rdtgrp = kzalloc(sizeof(*rdtgrp), GFP_KERNEL);
+ if (!rdtgrp) {
+ ret = -ENOSPC;
+ goto out_closid_free;
+ }
+ rdtgrp->closid = closid;
+ list_add(&rdtgrp->rdtgroup_list, &rdt_all_groups);
+
+ /* kernfs creates the directory for rdtgrp */
+ kn = kernfs_create_dir(parent->kn, name, mode, rdtgrp);
+ if (IS_ERR(kn)) {
+ ret = PTR_ERR(kn);
+ goto out_cancel_ref;
+ }
+ rdtgrp->kn = kn;
+
+ /*
+ * kernfs_remove() will drop the reference count on "kn" which
+ * will free it. But we still need it to stick around for the
+ * rdtgroup_kn_unlock(kn} call below. Take one extra reference
+ * here, which will be dropped inside rdtgroup_kn_unlock().
+ */
+ kernfs_get(kn);
+
+ ret = rdtgroup_kn_set_ugid(kn);
+ if (ret)
+ goto out_destroy;
+
+ kernfs_activate(kn);
+
+ ret = 0;
+ goto out_unlock;
+
+out_destroy:
+ kernfs_remove(rdtgrp->kn);
+out_cancel_ref:
+ list_del(&rdtgrp->rdtgroup_list);
+ kfree(rdtgrp);
+out_closid_free:
+ closid_free(closid);
+out_unlock:
+ rdtgroup_kn_unlock(parent_kn);
+ return ret;
+}
+
+static int rdtgroup_rmdir(struct kernfs_node *kn)
+{
+ struct rdtgroup *rdtgrp;
+ int ret = 0;
+
+ rdtgrp = rdtgroup_kn_lock_live(kn);
+ if (!rdtgrp) {
+ rdtgroup_kn_unlock(kn);
+ return -ENOENT;
+ }
+
+ rdtgrp->flags = RDT_DELETED;
+ closid_free(rdtgrp->closid);
+ list_del(&rdtgrp->rdtgroup_list);
+
+ /*
+ * one extra hold on this, will drop when we kfree(rdtgrp)
+ * in rdtgroup_kn_unlock()
+ */
+ kernfs_get(kn);
+ kernfs_remove(rdtgrp->kn);
+
+ rdtgroup_kn_unlock(kn);
+
+ return ret;
+}
+
static struct kernfs_syscall_ops rdtgroup_kf_syscall_ops = {
+ .mkdir = rdtgroup_mkdir,
+ .rmdir = rdtgroup_rmdir,
};
static int __init rdtgroup_setup_root(void)
projects / users / willy / xarray.git / commitdiff