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From:   Frederic Barrat <fbarrat@linux.vnet.ibm.com>
To:     linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Cc:     arnd@arndb.de, gregkh@linuxfoundation.org, mpe@ellerman.id.au,
        andrew.donnellan@au1.ibm.com, alastair@au1.ibm.com
Subject: [PATCH v2 07/13] ocxl: Add AFU interrupt support
Date:   Tue, 23 Jan 2018 12:31:42 +0100
In-Reply-To: <20180123113148.6024-1-fbarrat@linux.vnet.ibm.com>
References: <20180123113148.6024-1-fbarrat@linux.vnet.ibm.com>
Message-Id: <20180123113148.6024-8-fbarrat@linux.vnet.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Add user APIs through ioctl to allocate, free, and be notified of an
AFU interrupt.

For opencapi, an AFU can trigger an interrupt on the host by sending a
specific command targeting a 64-bit object handle. On POWER9, this is
implemented by mapping a special page in the address space of a
process and a write to that page will trigger an interrupt.

Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/pnv-ocxl.h   |   3 +
 arch/powerpc/platforms/powernv/ocxl.c |  30 ++++++
 drivers/misc/ocxl/afu_irq.c           | 197 ++++++++++++++++++++++++++++++++++
 drivers/misc/ocxl/context.c           |  51 ++++++++-
 drivers/misc/ocxl/file.c              |  34 ++++++
 drivers/misc/ocxl/link.c              |  28 +++++
 drivers/misc/ocxl/ocxl_internal.h     |   7 ++
 include/uapi/misc/ocxl.h              |   9 ++
 8 files changed, 357 insertions(+), 2 deletions(-)
 create mode 100644 drivers/misc/ocxl/afu_irq.c

diff --git a/arch/powerpc/include/asm/pnv-ocxl.h b/arch/powerpc/include/asm/pnv-ocxl.h
index 398d05b30600..f6945d3bc971 100644
--- a/arch/powerpc/include/asm/pnv-ocxl.h
+++ b/arch/powerpc/include/asm/pnv-ocxl.h
@@ -30,4 +30,7 @@ extern int pnv_ocxl_spa_setup(struct pci_dev *dev, void *spa_mem, int PE_mask,
 extern void pnv_ocxl_spa_release(void *platform_data);
 extern int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle);
 
+extern int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr);
+extern void pnv_ocxl_free_xive_irq(u32 irq);
+
 #endif /* _ASM_PNV_OCXL_H */
diff --git a/arch/powerpc/platforms/powernv/ocxl.c b/arch/powerpc/platforms/powernv/ocxl.c
index 1faaa4ef6903..fa9b53af3c7b 100644
--- a/arch/powerpc/platforms/powernv/ocxl.c
+++ b/arch/powerpc/platforms/powernv/ocxl.c
@@ -2,6 +2,7 @@
 // Copyright 2017 IBM Corp.
 #include <asm/pnv-ocxl.h>
 #include <asm/opal.h>
+#include <asm/xive.h>
 #include <misc/ocxl-config.h>
 #include "pci.h"
 
@@ -483,3 +484,32 @@ int pnv_ocxl_spa_remove_pe(void *platform_data, int pe_handle)
 	return rc;
 }
 EXPORT_SYMBOL_GPL(pnv_ocxl_spa_remove_pe);
+
+int pnv_ocxl_alloc_xive_irq(u32 *irq, u64 *trigger_addr)
+{
+	__be64 flags, trigger_page;
+	s64 rc;
+	u32 hwirq;
+
+	hwirq = xive_native_alloc_irq();
+	if (!hwirq)
+		return -ENOENT;
+
+	rc = opal_xive_get_irq_info(hwirq, &flags, NULL, &trigger_page, NULL,
+				NULL);
+	if (rc || !trigger_page) {
+		xive_native_free_irq(hwirq);
+		return -ENOENT;
+	}
+	*irq = hwirq;
+	*trigger_addr = be64_to_cpu(trigger_page);
+	return 0;
+
+}
+EXPORT_SYMBOL_GPL(pnv_ocxl_alloc_xive_irq);
+
+void pnv_ocxl_free_xive_irq(u32 irq)
+{
+	xive_native_free_irq(irq);
+}
+EXPORT_SYMBOL_GPL(pnv_ocxl_free_xive_irq);
diff --git a/drivers/misc/ocxl/afu_irq.c b/drivers/misc/ocxl/afu_irq.c
new file mode 100644
index 000000000000..f40d853de401
--- /dev/null
+++ b/drivers/misc/ocxl/afu_irq.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright 2017 IBM Corp.
+#include <linux/interrupt.h>
+#include <linux/eventfd.h>
+#include <asm/pnv-ocxl.h>
+#include "ocxl_internal.h"
+
+struct afu_irq {
+	int id;
+	int hw_irq;
+	unsigned int virq;
+	char *name;
+	u64 trigger_page;
+	struct eventfd_ctx *ev_ctx;
+};
+
+static int irq_offset_to_id(struct ocxl_context *ctx, u64 offset)
+{
+	return (offset - ctx->afu->irq_base_offset) >> PAGE_SHIFT;
+}
+
+static u64 irq_id_to_offset(struct ocxl_context *ctx, int id)
+{
+	return ctx->afu->irq_base_offset + (id << PAGE_SHIFT);
+}
+
+static irqreturn_t afu_irq_handler(int virq, void *data)
+{
+	struct afu_irq *irq = (struct afu_irq *) data;
+
+	if (irq->ev_ctx)
+		eventfd_signal(irq->ev_ctx, 1);
+	return IRQ_HANDLED;
+}
+
+static int setup_afu_irq(struct ocxl_context *ctx, struct afu_irq *irq)
+{
+	int rc;
+
+	irq->virq = irq_create_mapping(NULL, irq->hw_irq);
+	if (!irq->virq) {
+		pr_err("irq_create_mapping failed\n");
+		return -ENOMEM;
+	}
+	pr_debug("hw_irq %d mapped to virq %u\n", irq->hw_irq, irq->virq);
+
+	irq->name = kasprintf(GFP_KERNEL, "ocxl-afu-%u", irq->virq);
+	if (!irq->name) {
+		irq_dispose_mapping(irq->virq);
+		return -ENOMEM;
+	}
+
+	rc = request_irq(irq->virq, afu_irq_handler, 0, irq->name, irq);
+	if (rc) {
+		kfree(irq->name);
+		irq->name = NULL;
+		irq_dispose_mapping(irq->virq);
+		pr_err("request_irq failed: %d\n", rc);
+		return rc;
+	}
+	return 0;
+}
+
+static void release_afu_irq(struct afu_irq *irq)
+{
+	free_irq(irq->virq, irq);
+	irq_dispose_mapping(irq->virq);
+	kfree(irq->name);
+}
+
+int ocxl_afu_irq_alloc(struct ocxl_context *ctx, u64 *irq_offset)
+{
+	struct afu_irq *irq;
+	int rc;
+
+	irq = kzalloc(sizeof(struct afu_irq), GFP_KERNEL);
+	if (!irq)
+		return -ENOMEM;
+
+	/*
+	 * We limit the number of afu irqs per context and per link to
+	 * avoid a single process or user depleting the pool of IPIs
+	 */
+
+	mutex_lock(&ctx->irq_lock);
+
+	irq->id = idr_alloc(&ctx->irq_idr, irq, 0, MAX_IRQ_PER_CONTEXT,
+			GFP_KERNEL);
+	if (irq->id < 0) {
+		rc = -ENOSPC;
+		goto err_unlock;
+	}
+
+	rc = ocxl_link_irq_alloc(ctx->afu->fn->link, &irq->hw_irq,
+				&irq->trigger_page);
+	if (rc)
+		goto err_idr;
+
+	rc = setup_afu_irq(ctx, irq);
+	if (rc)
+		goto err_alloc;
+
+	*irq_offset = irq_id_to_offset(ctx, irq->id);
+
+	mutex_unlock(&ctx->irq_lock);
+	return 0;
+
+err_alloc:
+	ocxl_link_free_irq(ctx->afu->fn->link, irq->hw_irq);
+err_idr:
+	idr_remove(&ctx->irq_idr, irq->id);
+err_unlock:
+	mutex_unlock(&ctx->irq_lock);
+	kfree(irq);
+	return rc;
+}
+
+static void afu_irq_free(struct afu_irq *irq, struct ocxl_context *ctx)
+{
+	if (ctx->mapping)
+		unmap_mapping_range(ctx->mapping,
+				irq_id_to_offset(ctx, irq->id),
+				1 << PAGE_SHIFT, 1);
+	release_afu_irq(irq);
+	if (irq->ev_ctx)
+		eventfd_ctx_put(irq->ev_ctx);
+	ocxl_link_free_irq(ctx->afu->fn->link, irq->hw_irq);
+	kfree(irq);
+}
+
+int ocxl_afu_irq_free(struct ocxl_context *ctx, u64 irq_offset)
+{
+	struct afu_irq *irq;
+	int id = irq_offset_to_id(ctx, irq_offset);
+
+	mutex_lock(&ctx->irq_lock);
+
+	irq = idr_find(&ctx->irq_idr, id);
+	if (!irq) {
+		mutex_unlock(&ctx->irq_lock);
+		return -EINVAL;
+	}
+	idr_remove(&ctx->irq_idr, irq->id);
+	afu_irq_free(irq, ctx);
+	mutex_unlock(&ctx->irq_lock);
+	return 0;
+}
+
+void ocxl_afu_irq_free_all(struct ocxl_context *ctx)
+{
+	struct afu_irq *irq;
+	int id;
+
+	mutex_lock(&ctx->irq_lock);
+	idr_for_each_entry(&ctx->irq_idr, irq, id)
+		afu_irq_free(irq, ctx);
+	mutex_unlock(&ctx->irq_lock);
+}
+
+int ocxl_afu_irq_set_fd(struct ocxl_context *ctx, u64 irq_offset, int eventfd)
+{
+	struct afu_irq *irq;
+	struct eventfd_ctx *ev_ctx;
+	int rc = 0, id = irq_offset_to_id(ctx, irq_offset);
+
+	mutex_lock(&ctx->irq_lock);
+	irq = idr_find(&ctx->irq_idr, id);
+	if (!irq) {
+		rc = -EINVAL;
+		goto unlock;
+	}
+
+	ev_ctx = eventfd_ctx_fdget(eventfd);
+	if (IS_ERR(ev_ctx)) {
+		rc = -EINVAL;
+		goto unlock;
+	}
+
+	irq->ev_ctx = ev_ctx;
+unlock:
+	mutex_unlock(&ctx->irq_lock);
+	return rc;
+}
+
+u64 ocxl_afu_irq_get_addr(struct ocxl_context *ctx, u64 irq_offset)
+{
+	struct afu_irq *irq;
+	int id = irq_offset_to_id(ctx, irq_offset);
+	u64 addr = 0;
+
+	mutex_lock(&ctx->irq_lock);
+	irq = idr_find(&ctx->irq_idr, id);
+	if (irq)
+		addr = irq->trigger_page;
+	mutex_unlock(&ctx->irq_lock);
+	return addr;
+}
diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c
index b34b836f924c..269149490063 100644
--- a/drivers/misc/ocxl/context.c
+++ b/drivers/misc/ocxl/context.c
@@ -31,6 +31,8 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
 	mutex_init(&ctx->mapping_lock);
 	init_waitqueue_head(&ctx->events_wq);
 	mutex_init(&ctx->xsl_error_lock);
+	mutex_init(&ctx->irq_lock);
+	idr_init(&ctx->irq_idr);
 	/*
 	 * Keep a reference on the AFU to make sure it's valid for the
 	 * duration of the life of the context
@@ -80,6 +82,19 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 	return rc;
 }
 
+static int map_afu_irq(struct vm_area_struct *vma, unsigned long address,
+		u64 offset, struct ocxl_context *ctx)
+{
+	u64 trigger_addr;
+
+	trigger_addr = ocxl_afu_irq_get_addr(ctx, offset);
+	if (!trigger_addr)
+		return VM_FAULT_SIGBUS;
+
+	vm_insert_pfn(vma, address, trigger_addr >> PAGE_SHIFT);
+	return VM_FAULT_NOPAGE;
+}
+
 static int map_pp_mmio(struct vm_area_struct *vma, unsigned long address,
 		u64 offset, struct ocxl_context *ctx)
 {
@@ -118,7 +133,10 @@ static int ocxl_mmap_fault(struct vm_fault *vmf)
 	pr_debug("%s: pasid %d address 0x%lx offset 0x%llx\n", __func__,
 		ctx->pasid, vmf->address, offset);
 
-	rc = map_pp_mmio(vma, vmf->address, offset, ctx);
+	if (offset < ctx->afu->irq_base_offset)
+		rc = map_pp_mmio(vma, vmf->address, offset, ctx);
+	else
+		rc = map_afu_irq(vma, vmf->address, offset, ctx);
 	return rc;
 }
 
@@ -126,6 +144,30 @@ static const struct vm_operations_struct ocxl_vmops = {
 	.fault = ocxl_mmap_fault,
 };
 
+static int check_mmap_afu_irq(struct ocxl_context *ctx,
+			struct vm_area_struct *vma)
+{
+	/* only one page */
+	if (vma_pages(vma) != 1)
+		return -EINVAL;
+
+	/* check offset validty */
+	if (!ocxl_afu_irq_get_addr(ctx, vma->vm_pgoff << PAGE_SHIFT))
+		return -EINVAL;
+
+	/*
+	 * trigger page should only be accessible in write mode.
+	 *
+	 * It's a bit theoretical, as a page mmaped with only
+	 * PROT_WRITE is currently readable, but it doesn't hurt.
+	 */
+	if ((vma->vm_flags & VM_READ) || (vma->vm_flags & VM_EXEC) ||
+		!(vma->vm_flags & VM_WRITE))
+		return -EINVAL;
+	vma->vm_flags &= ~(VM_MAYREAD | VM_MAYEXEC);
+	return 0;
+}
+
 static int check_mmap_mmio(struct ocxl_context *ctx,
 			struct vm_area_struct *vma)
 {
@@ -139,7 +181,10 @@ int ocxl_context_mmap(struct ocxl_context *ctx, struct vm_area_struct *vma)
 {
 	int rc;
 
-	rc = check_mmap_mmio(ctx, vma);
+	if ((vma->vm_pgoff << PAGE_SHIFT) < ctx->afu->irq_base_offset)
+		rc = check_mmap_mmio(ctx, vma);
+	else
+		rc = check_mmap_afu_irq(ctx, vma);
 	if (rc)
 		return rc;
 
@@ -224,6 +269,8 @@ void ocxl_context_free(struct ocxl_context *ctx)
 	idr_remove(&ctx->afu->contexts_idr, ctx->pasid);
 	mutex_unlock(&ctx->afu->contexts_lock);
 
+	ocxl_afu_irq_free_all(ctx);
+	idr_destroy(&ctx->irq_idr);
 	/* reference to the AFU taken in ocxl_context_init */
 	ocxl_afu_put(ctx->afu);
 	kfree(ctx);
diff --git a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c
index 6f0befda6a8a..c90c1a578d2f 100644
--- a/drivers/misc/ocxl/file.c
+++ b/drivers/misc/ocxl/file.c
@@ -103,12 +103,17 @@ static long afu_ioctl_attach(struct ocxl_context *ctx,
 }
 
 #define CMD_STR(x) (x == OCXL_IOCTL_ATTACH ? "ATTACH" :			\
+			x == OCXL_IOCTL_IRQ_ALLOC ? "IRQ_ALLOC" :	\
+			x == OCXL_IOCTL_IRQ_FREE ? "IRQ_FREE" :		\
+			x == OCXL_IOCTL_IRQ_SET_FD ? "IRQ_SET_FD" :	\
 			"UNKNOWN")
 
 static long afu_ioctl(struct file *file, unsigned int cmd,
 		unsigned long args)
 {
 	struct ocxl_context *ctx = file->private_data;
+	struct ocxl_ioctl_irq_fd irq_fd;
+	u64 irq_offset;
 	long rc;
 
 	pr_debug("%s for context %d, command %s\n", __func__, ctx->pasid,
@@ -123,6 +128,35 @@ static long afu_ioctl(struct file *file, unsigned int cmd,
 				(struct ocxl_ioctl_attach __user *) args);
 		break;
 
+	case OCXL_IOCTL_IRQ_ALLOC:
+		rc = ocxl_afu_irq_alloc(ctx, &irq_offset);
+		if (!rc) {
+			rc = copy_to_user((u64 __user *) args, &irq_offset,
+					sizeof(irq_offset));
+			if (rc)
+				ocxl_afu_irq_free(ctx, irq_offset);
+		}
+		break;
+
+	case OCXL_IOCTL_IRQ_FREE:
+		rc = copy_from_user(&irq_offset, (u64 __user *) args,
+				sizeof(irq_offset));
+		if (rc)
+			return -EFAULT;
+		rc = ocxl_afu_irq_free(ctx, irq_offset);
+		break;
+
+	case OCXL_IOCTL_IRQ_SET_FD:
+		rc = copy_from_user(&irq_fd, (u64 __user *) args,
+				sizeof(irq_fd));
+		if (rc)
+			return -EFAULT;
+		if (irq_fd.reserved)
+			return -EINVAL;
+		rc = ocxl_afu_irq_set_fd(ctx, irq_fd.irq_offset,
+					irq_fd.eventfd);
+		break;
+
 	default:
 		rc = -EINVAL;
 	}
diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 64d7a98c904a..8bdcef9c3cba 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -601,3 +601,31 @@ int ocxl_link_remove_pe(void *link_handle, int pasid)
 	mutex_unlock(&spa->spa_lock);
 	return rc;
 }
+
+int ocxl_link_irq_alloc(void *link_handle, int *hw_irq, u64 *trigger_addr)
+{
+	struct link *link = (struct link *) link_handle;
+	int rc, irq;
+	u64 addr;
+
+	if (atomic_dec_if_positive(&link->irq_available) < 0)
+		return -ENOSPC;
+
+	rc = pnv_ocxl_alloc_xive_irq(&irq, &addr);
+	if (rc) {
+		atomic_inc(&link->irq_available);
+		return rc;
+	}
+
+	*hw_irq = irq;
+	*trigger_addr = addr;
+	return 0;
+}
+
+void ocxl_link_free_irq(void *link_handle, int hw_irq)
+{
+	struct link *link = (struct link *) link_handle;
+
+	pnv_ocxl_free_xive_irq(hw_irq);
+	atomic_inc(&link->irq_available);
+}
diff --git a/drivers/misc/ocxl/ocxl_internal.h b/drivers/misc/ocxl/ocxl_internal.h
index 04fc160c7bd5..a89b88ac67eb 100644
--- a/drivers/misc/ocxl/ocxl_internal.h
+++ b/drivers/misc/ocxl/ocxl_internal.h
@@ -190,4 +190,11 @@ extern void ocxl_context_free(struct ocxl_context *ctx);
 extern int ocxl_sysfs_add_afu(struct ocxl_afu *afu);
 extern void ocxl_sysfs_remove_afu(struct ocxl_afu *afu);
 
+extern int ocxl_afu_irq_alloc(struct ocxl_context *ctx, u64 *irq_offset);
+extern int ocxl_afu_irq_free(struct ocxl_context *ctx, u64 irq_offset);
+extern void ocxl_afu_irq_free_all(struct ocxl_context *ctx);
+extern int ocxl_afu_irq_set_fd(struct ocxl_context *ctx, u64 irq_offset,
+			int eventfd);
+extern u64 ocxl_afu_irq_get_addr(struct ocxl_context *ctx, u64 irq_offset);
+
 #endif /* _OCXL_INTERNAL_H_ */
diff --git a/include/uapi/misc/ocxl.h b/include/uapi/misc/ocxl.h
index a37e34edf52f..4b0b0b756f3e 100644
--- a/include/uapi/misc/ocxl.h
+++ b/include/uapi/misc/ocxl.h
@@ -32,9 +32,18 @@ struct ocxl_ioctl_attach {
 	__u64 reserved3;
 };
 
+struct ocxl_ioctl_irq_fd {
+	__u64 irq_offset;
+	__s32 eventfd;
+	__u32 reserved;
+};
+
 /* ioctl numbers */
 #define OCXL_MAGIC 0xCA
 /* AFU devices */
 #define OCXL_IOCTL_ATTACH	_IOW(OCXL_MAGIC, 0x10, struct ocxl_ioctl_attach)
+#define OCXL_IOCTL_IRQ_ALLOC	_IOR(OCXL_MAGIC, 0x11, __u64)
+#define OCXL_IOCTL_IRQ_FREE	_IOW(OCXL_MAGIC, 0x12, __u64)
+#define OCXL_IOCTL_IRQ_SET_FD	_IOW(OCXL_MAGIC, 0x13, struct ocxl_ioctl_irq_fd)
 
 #endif /* _UAPI_MISC_OCXL_H */
-- 
2.14.1