[PATCH 03/10] VFIO: platform: Direct EOI irq bypass for ARM/ARM64

Eric Auger
2017-05-24T20:10:04Z

This patch adds the registration/unregistration of an
irq_bypass_producer for vfio platform device interrupts.

Its callbacks handle the direct EOI modality on VFIO side.

- stop/start: disable/enable the host irq
- add/del consumer: set the VFIO Direct EOI mode, ie. select the
adapted physical IRQ handler (automasked or not automasked).

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---
---
drivers/vfio/platform/Kconfig | 5 +
drivers/vfio/platform/Makefile | 2 +-
drivers/vfio/platform/vfio_platform_irq.c | 19 ++++
drivers/vfio/platform/vfio_platform_irq_bypass.c | 114 +++++++++++++++++++++++
drivers/vfio/platform/vfio_platform_private.h | 23 +++++
5 files changed, 162 insertions(+), 1 deletion(-)
create mode 100644 drivers/vfio/platform/vfio_platform_irq_bypass.c

diff --git a/drivers/vfio/platform/Kconfig b/drivers/vfio/platform/Kconfig
index bb30128..33ec3d9 100644
--- a/drivers/vfio/platform/Kconfig
+++ b/drivers/vfio/platform/Kconfig
@@ -2,6 +2,7 @@ config VFIO_PLATFORM
tristate "VFIO support for platform devices"
depends on VFIO && EVENTFD && (ARM || ARM64)
select VFIO_VIRQFD
+ select IRQ_BYPASS_MANAGER
help
Support for platform devices with VFIO. This is required to make
use of platform devices present on the system using the VFIO
@@ -19,4 +20,8 @@ config VFIO_AMBA

If you don't know what to do here, say N.

+config VFIO_PLATFORM_IRQ_BYPASS_DEOI
+ depends on VFIO_PLATFORM
+ def_bool y
+
source "drivers/vfio/platform/reset/Kconfig"
diff --git a/drivers/vfio/platform/Makefile b/drivers/vfio/platform/Makefile
index 41a6224..324f3e7 100644
--- a/drivers/vfio/platform/Makefile
+++ b/drivers/vfio/platform/Makefile
@@ -1,4 +1,4 @@
-vfio-platform-base-y := vfio_platform_common.o vfio_platform_irq.o
+vfio-platform-base-y := vfio_platform_common.o vfio_platform_irq.o vfio_platform_irq_bypass.o
vfio-platform-y := vfio_platform.o

obj-$(CONFIG_VFIO_PLATFORM) += vfio-platform.o
diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
index 2f82459..5b70c8e 100644
--- a/drivers/vfio/platform/vfio_platform_irq.c
+++ b/drivers/vfio/platform/vfio_platform_irq.c
@@ -20,6 +20,7 @@
#include <linux/types.h>
#include <linux/vfio.h>
#include <linux/irq.h>
+#include <linux/irqbypass.h>

#include "vfio_platform_private.h"

@@ -186,6 +187,19 @@ static irqreturn_t vfio_wrapper_handler(int irq, void *dev_id)
return ret;
}

+/* must be called with irq_ctx->lock held */
+int vfio_platform_set_deoi(struct vfio_platform_irq *irq_ctx, bool deoi)
+{
+ irq_ctx->deoi = deoi;
+
+ if (!deoi && (irq_ctx->flags & VFIO_IRQ_INFO_AUTOMASKED))
+ irq_ctx->handler = vfio_automasked_irq_handler;
+ else
+ irq_ctx->handler = vfio_irq_handler;
+
+ return 0;
+}
+
static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
int fd, irq_handler_t handler)
{
@@ -196,6 +210,7 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
if (irq->trigger) {
irq_clear_status_flags(irq->hwirq, IRQ_NOAUTOEN);
free_irq(irq->hwirq, irq);
+ irq_bypass_unregister_producer(&irq->producer);
kfree(irq->name);
eventfd_ctx_put(irq->trigger);
irq->trigger = NULL;
@@ -227,6 +242,10 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
return ret;
}

+ if (vfio_platform_has_deoi())
+ vfio_platform_register_deoi_producer(vdev, irq,
+ trigger, irq->hwirq);
+
if (!irq->masked)
enable_irq(irq->hwirq);

diff --git a/drivers/vfio/platform/vfio_platform_irq_bypass.c b/drivers/vfio/platform/vfio_platform_irq_bypass.c
new file mode 100644
index 0000000..436902c
--- /dev/null
+++ b/drivers/vfio/platform/vfio_platform_irq_bypass.c
@@ -0,0 +1,114 @@
+/*
+ * VFIO platform device irqbypass callback implementation for DEOI
+ *
+ * Copyright (C) 2017 Red Hat, Inc. All rights reserved.
+ * Author: Eric Auger <eric.auger@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/irq.h>
+#include <linux/irqbypass.h>
+#include "vfio_platform_private.h"
+
+#ifdef CONFIG_VFIO_PLATFORM_IRQ_BYPASS_DEOI
+
+static void irq_bypass_deoi_start(struct irq_bypass_producer *prod)
+{
+ enable_irq(prod->irq);
+}
+
+static void irq_bypass_deoi_stop(struct irq_bypass_producer *prod)
+{
+ disable_irq(prod->irq);
+}
+
+/**
+ * irq_bypass_deoi_add_consumer - turns irq direct EOI on
+ *
+ * The linux irq is disabled when the function is called.
+ * The operation succeeds only if the irq is not active at irqchip level
+ * and the irq is not automasked at VFIO level, meaning the IRQ is under
+ * injection into the guest.
+ */
+static int irq_bypass_deoi_add_consumer(struct irq_bypass_producer *prod,
+ struct irq_bypass_consumer *cons)
+{
+ struct vfio_platform_irq *irq_ctx =
+ container_of(prod, struct vfio_platform_irq, producer);
+ unsigned long flags;
+ bool active;
+ int ret;
+
+ spin_lock_irqsave(&irq_ctx->lock, flags);
+
+ ret = irq_get_irqchip_state(irq_ctx->hwirq, IRQCHIP_STATE_ACTIVE,
+ &active);
+ if (ret)
+ goto out;
+
+ if (active || irq_ctx->automasked) {
+ ret = -EAGAIN;
+ goto out;
+ }
+
+ if (!(irq_get_trigger_type(irq_ctx->hwirq) & IRQ_TYPE_LEVEL_MASK))
+ goto out;
+
+ ret = vfio_platform_set_deoi(irq_ctx, true);
+out:
+ spin_unlock_irqrestore(&irq_ctx->lock, flags);
+ return ret;
+}
+
+static void irq_bypass_deoi_del_consumer(struct irq_bypass_producer *prod,
+ struct irq_bypass_consumer *cons)
+{
+ struct vfio_platform_irq *irq_ctx =
+ container_of(prod, struct vfio_platform_irq, producer);
+ unsigned long flags;
+
+ spin_lock_irqsave(&irq_ctx->lock, flags);
+ if (irq_get_trigger_type(irq_ctx->hwirq) & IRQ_TYPE_LEVEL_MASK)
+ vfio_platform_set_deoi(irq_ctx, false);
+ spin_unlock_irqrestore(&irq_ctx->lock, flags);
+}
+
+bool vfio_platform_has_deoi(void)
+{
+ return true;
+}
+
+void vfio_platform_register_deoi_producer(struct vfio_platform_device *vdev,
+ struct vfio_platform_irq *irq,
+ struct eventfd_ctx *trigger,
+ unsigned int host_irq)
+{
+ struct irq_bypass_producer *prod = &irq->producer;
+ int ret;
+
+ prod->token = trigger;
+ prod->irq = host_irq;
+ prod->add_consumer = irq_bypass_deoi_add_consumer;
+ prod->del_consumer = irq_bypass_deoi_del_consumer;
+ prod->stop = irq_bypass_deoi_stop;
+ prod->start = irq_bypass_deoi_start;
+
+ ret = irq_bypass_register_producer(prod);
+ if (unlikely(ret))
+ dev_info(vdev->device,
+ "irq bypass producer (token %p) registration fails: %d\n",
+ prod->token, ret);
+}
+
+#endif
+
diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index b80a380..bfa2675 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -17,6 +17,7 @@

#include <linux/types.h>
#include <linux/interrupt.h>
+#include <linux/irqbypass.h>

#define VFIO_PLATFORM_OFFSET_SHIFT 40
#define VFIO_PLATFORM_OFFSET_MASK (((u64)(1) << VFIO_PLATFORM_OFFSET_SHIFT) - 1)
@@ -40,6 +41,7 @@ struct vfio_platform_irq {
struct virqfd *mask;
bool deoi;
irqreturn_t (*handler)(int irq, void *dev_id);
+ struct irq_bypass_producer producer;
};

struct vfio_platform_region {
@@ -102,9 +104,30 @@ extern int vfio_platform_set_irqs_ioctl(struct vfio_platform_device *vdev,
unsigned start, unsigned count,
void *data);

+extern int vfio_platform_set_deoi(struct vfio_platform_irq *irq_ctx, bool deoi);
+
extern void __vfio_platform_register_reset(struct vfio_platform_reset_node *n);
extern void vfio_platform_unregister_reset(const char *compat,
vfio_platform_reset_fn_t fn);
+
+#ifdef CONFIG_VFIO_PLATFORM_IRQ_BYPASS_DEOI
+bool vfio_platform_has_deoi(void);
+void vfio_platform_register_deoi_producer(struct vfio_platform_device *vdev,
+ struct vfio_platform_irq *irq,
+ struct eventfd_ctx *trigger,
+ unsigned int host_irq);
+#else
+static inline bool vfio_platform_has_deoi(void)
+{
+ return false;
+}
+static inline
+void vfio_platform_register_deoi_producer(struct vfio_platform_device *vdev,
+ struct vfio_platform_irq *irq,
+ struct eventfd_ctx *trigger,
+ unsigned int host_irq) {}
+#endif
+
#define vfio_platform_register_reset(__compat, __reset) \
static struct vfio_platform_reset_node __reset ## _node = { \
.owner = THIS_MODULE, \
--
2.5.5