sched_ext: Maintain an online cid mask in the scheduler arenagrafted

Schedulers on the default cid mapping treat [0, nr_online_cids) as the
online set and restart on hotplug. Schedulers that install their own mapping
with scx_bpf_cid_override() have no way to learn which cids are online: the
count no longer identifies members and the CPU-form cpumask is unusable from
cid programs. This is an obvious hole in the cid API.

Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's
arena, allocated alongside the per-CPU scratch masks and populated after the
cid mapping is finalized and before ops.init(), for child schedulers too.
The pointer stays valid through ops.exit() with no reference to take. It is
the arena offset as a void pointer, the same form struct_ops arena arguments
arrive in. The verifier types the void return as a scalar for the program's
arena cast.

The mask follows the SCX hotplug notifications: seeded from cpu_active_mask
and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask
only inside a hotplug transition. Updates walk the scheduler list under the
lock that also serializes unlinking. Reads are live, not atomic snapshots.
Root initialization excludes hotplug.

v2: Reworded the getter kerneldoc (Andrea Righi).

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

1 files changed, 325 insertions, 0 deletions

diff --git a/drivers/crypto/ccp/sp-dev.c b/drivers/crypto/ccp/sp-dev.c
new file mode 100644
index 000000000..f204aa5df
--- /dev/null
+++ b/drivers/crypto/ccp/sp-dev.c
@@ -0,0 +1,325 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AMD Secure Processor driver
+ *
+ * Copyright (C) 2017-2018 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <thomas.lendacky@amd.com>
+ * Author: Gary R Hook <gary.hook@amd.com>
+ * Author: Brijesh Singh <brijesh.singh@amd.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/spinlock_types.h>
+#include <linux/types.h>
+#include <linux/ccp.h>
+
+#include "sev-dev.h"
+#include "ccp-dev.h"
+#include "sp-dev.h"
+
+MODULE_AUTHOR("Tom Lendacky <thomas.lendacky@amd.com>");
+MODULE_AUTHOR("Gary R Hook <gary.hook@amd.com>");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1.1.0");
+MODULE_DESCRIPTION("AMD Secure Processor driver");
+
+/* List of SPs, SP count, read-write access lock, and access functions
+ *
+ * Lock structure: get sp_unit_lock for reading whenever we need to
+ * examine the SP list.
+ */
+static DEFINE_RWLOCK(sp_unit_lock);
+static LIST_HEAD(sp_units);
+
+/* Ever-increasing value to produce unique unit numbers */
+static atomic_t sp_ordinal;
+
+static void sp_add_device(struct sp_device *sp)
+{
+	unsigned long flags;
+
+	write_lock_irqsave(&sp_unit_lock, flags);
+
+	list_add_tail(&sp->entry, &sp_units);
+
+	write_unlock_irqrestore(&sp_unit_lock, flags);
+}
+
+static void sp_del_device(struct sp_device *sp)
+{
+	unsigned long flags;
+
+	write_lock_irqsave(&sp_unit_lock, flags);
+
+	list_del(&sp->entry);
+
+	write_unlock_irqrestore(&sp_unit_lock, flags);
+}
+
+static irqreturn_t sp_irq_handler(int irq, void *data)
+{
+	struct sp_device *sp = data;
+
+	if (sp->ccp_irq_handler)
+		sp->ccp_irq_handler(irq, sp->ccp_irq_data);
+
+	if (sp->psp_irq_handler)
+		sp->psp_irq_handler(irq, sp->psp_irq_data);
+
+	return IRQ_HANDLED;
+}
+
+int sp_request_ccp_irq(struct sp_device *sp, irq_handler_t handler,
+		       const char *name, void *data)
+{
+	int ret;
+
+	if ((sp->psp_irq == sp->ccp_irq) && sp->dev_vdata->psp_vdata) {
+		/* Need a common routine to manage all interrupts */
+		sp->ccp_irq_data = data;
+		sp->ccp_irq_handler = handler;
+
+		if (!sp->irq_registered) {
+			ret = request_irq(sp->ccp_irq, sp_irq_handler, 0,
+					  sp->name, sp);
+			if (ret)
+				return ret;
+
+			sp->irq_registered = true;
+		}
+	} else {
+		/* Each sub-device can manage it's own interrupt */
+		ret = request_irq(sp->ccp_irq, handler, 0, name, data);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+int sp_request_psp_irq(struct sp_device *sp, irq_handler_t handler,
+		       const char *name, void *data)
+{
+	int ret;
+
+	if ((sp->psp_irq == sp->ccp_irq) && sp->dev_vdata->ccp_vdata) {
+		/* Need a common routine to manage all interrupts */
+		sp->psp_irq_data = data;
+		sp->psp_irq_handler = handler;
+
+		if (!sp->irq_registered) {
+			ret = request_irq(sp->psp_irq, sp_irq_handler, 0,
+					  sp->name, sp);
+			if (ret)
+				return ret;
+
+			sp->irq_registered = true;
+		}
+	} else {
+		/* Each sub-device can manage it's own interrupt */
+		ret = request_irq(sp->psp_irq, handler, 0, name, data);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+void sp_free_ccp_irq(struct sp_device *sp, void *data)
+{
+	if ((sp->psp_irq == sp->ccp_irq) && sp->dev_vdata->psp_vdata) {
+		/* Using common routine to manage all interrupts */
+		if (!sp->psp_irq_handler) {
+			/* Nothing else using it, so free it */
+			free_irq(sp->ccp_irq, sp);
+
+			sp->irq_registered = false;
+		}
+
+		sp->ccp_irq_handler = NULL;
+		sp->ccp_irq_data = NULL;
+	} else {
+		/* Each sub-device can manage it's own interrupt */
+		free_irq(sp->ccp_irq, data);
+	}
+}
+
+void sp_free_psp_irq(struct sp_device *sp, void *data)
+{
+	if ((sp->psp_irq == sp->ccp_irq) && sp->dev_vdata->ccp_vdata) {
+		/* Using common routine to manage all interrupts */
+		if (!sp->ccp_irq_handler) {
+			/* Nothing else using it, so free it */
+			free_irq(sp->psp_irq, sp);
+
+			sp->irq_registered = false;
+		}
+
+		sp->psp_irq_handler = NULL;
+		sp->psp_irq_data = NULL;
+	} else {
+		/* Each sub-device can manage it's own interrupt */
+		free_irq(sp->psp_irq, data);
+	}
+}
+
+/**
+ * sp_alloc_struct - allocate and initialize the sp_device struct
+ *
+ * @dev: device struct of the SP
+ */
+struct sp_device *sp_alloc_struct(struct device *dev)
+{
+	struct sp_device *sp;
+
+	sp = devm_kzalloc(dev, sizeof(*sp), GFP_KERNEL);
+	if (!sp)
+		return NULL;
+
+	sp->dev = dev;
+	sp->ord = atomic_inc_return(&sp_ordinal);
+	snprintf(sp->name, SP_MAX_NAME_LEN, "sp-%u", sp->ord);
+
+	return sp;
+}
+
+int sp_init(struct sp_device *sp)
+{
+	sp_add_device(sp);
+
+	if (sp->dev_vdata->ccp_vdata)
+		ccp_dev_init(sp);
+
+	if (sp->dev_vdata->psp_vdata)
+		psp_dev_init(sp);
+	return 0;
+}
+
+void sp_destroy(struct sp_device *sp)
+{
+	if (sp->dev_vdata->ccp_vdata)
+		ccp_dev_destroy(sp);
+
+	if (sp->dev_vdata->psp_vdata)
+		psp_dev_destroy(sp);
+
+	sp_del_device(sp);
+}
+
+int sp_suspend(struct sp_device *sp)
+{
+	if (sp->dev_vdata->ccp_vdata) {
+		ccp_dev_suspend(sp);
+	}
+
+	return 0;
+}
+
+int sp_resume(struct sp_device *sp)
+{
+	if (sp->dev_vdata->ccp_vdata) {
+		ccp_dev_resume(sp);
+	}
+
+	return 0;
+}
+
+int sp_restore(struct sp_device *sp)
+{
+	if (sp->psp_data) {
+		int ret = psp_restore(sp);
+
+		if (ret)
+			return ret;
+	}
+
+	return sp_resume(sp);
+}
+
+struct sp_device *sp_get_psp_master_device(void)
+{
+	struct sp_device *i, *ret = NULL;
+	unsigned long flags;
+
+	write_lock_irqsave(&sp_unit_lock, flags);
+	if (list_empty(&sp_units))
+		goto unlock;
+
+	list_for_each_entry(i, &sp_units, entry) {
+		if (i->psp_data && i->get_psp_master_device) {
+			ret = i->get_psp_master_device();
+			break;
+		}
+	}
+
+unlock:
+	write_unlock_irqrestore(&sp_unit_lock, flags);
+	return ret;
+}
+
+static int __init sp_mod_init(void)
+{
+#ifdef CONFIG_X86
+	static bool initialized;
+	int ret;
+
+	if (initialized)
+		return 0;
+
+	ret = sp_pci_init();
+	if (ret)
+		return ret;
+
+#ifdef CONFIG_CRYPTO_DEV_SP_PSP
+	psp_pci_init();
+#endif
+
+	initialized = true;
+
+	return 0;
+#endif
+
+#ifdef CONFIG_ARM64
+	int ret;
+
+	ret = sp_platform_init();
+	if (ret)
+		return ret;
+
+	return 0;
+#endif
+
+	return -ENODEV;
+}
+
+#if IS_BUILTIN(CONFIG_KVM_AMD) && IS_ENABLED(CONFIG_KVM_AMD_SEV)
+int __init sev_module_init(void)
+{
+	return sp_mod_init();
+}
+#endif
+
+static void __exit sp_mod_exit(void)
+{
+#ifdef CONFIG_X86
+
+#ifdef CONFIG_CRYPTO_DEV_SP_PSP
+	psp_pci_exit();
+#endif
+
+	sp_pci_exit();
+#endif
+
+#ifdef CONFIG_ARM64
+	sp_platform_exit();
+#endif
+}
+
+module_init(sp_mod_init);
+module_exit(sp_mod_exit);