[PATCH v15 03/10] hw/vfio/platform: add irq assignment

Eric Auger
2015-04-30T12:40:58Z

This patch adds the code requested to assign interrupts to
a guest. The interrupts are mediated through user handled
eventfds only.

Signed-off-by: Eric Auger <eric.auger@linaro.org>

---
v13 -> v14:
- remove virtualID field in header

v12 -> v13:
- start user-side eventfd handling at realize time
- remove start_irq_fn

v10 -> v11:
- use block declaration when possible
- change order of vfio_platform_eoi vs vfio_intp_interrupt
- introduce vfio_intp_inject_pending_lockheld following Alex Bennee
comments
- remove unmasking/masked when setting up VFIO signaling
- remove unused kvm_accel member in VFIOINTp struct
- add flags member in VFIOINTp in order to properly discriminate
edge/level-sensitive IRQs; unmask the physical IRQ only in case of
level-sensitive IRQ
- some comment rewording

v8 -> v9:
- free irq related resources in case of error in vfio_populate_device
---
hw/vfio/platform.c | 331 +++++++++++++++++++++++++++++++++++++++-
include/hw/vfio/vfio-platform.h | 31 ++++
trace-events | 7 +
3 files changed, 368 insertions(+), 1 deletion(-)

diff --git a/hw/vfio/platform.c b/hw/vfio/platform.c
index 569a675..35266a8 100644
--- a/hw/vfio/platform.c
+++ b/hw/vfio/platform.c
@@ -22,10 +22,299 @@
#include "qemu/range.h"
#include "sysemu/sysemu.h"
#include "exec/memory.h"
+#include "qemu/queue.h"
#include "hw/sysbus.h"
#include "trace.h"
#include "hw/platform-bus.h"

+/*
+ * Functions used whatever the injection method
+ */
+
+/**
+ * vfio_init_intp - allocate, initialize the IRQ struct pointer
+ * and add it into the list of IRQs
+ * @vbasedev: the VFIO device handle
+ * @info: irq info struct retrieved from VFIO driver
+ */
+static VFIOINTp *vfio_init_intp(VFIODevice *vbasedev,
+ struct vfio_irq_info info)
+{
+ int ret;
+ VFIOPlatformDevice *vdev =
+ container_of(vbasedev, VFIOPlatformDevice, vbasedev);
+ SysBusDevice *sbdev = SYS_BUS_DEVICE(vdev);
+ VFIOINTp *intp;
+
+ intp = g_malloc0(sizeof(*intp));
+ intp->vdev = vdev;
+ intp->pin = info.index;
+ intp->flags = info.flags;
+ intp->state = VFIO_IRQ_INACTIVE;
+
+ sysbus_init_irq(sbdev, &intp->qemuirq);
+
+ /* Get an eventfd for trigger */
+ ret = event_notifier_init(&intp->interrupt, 0);
+ if (ret) {
+ g_free(intp);
+ error_report("vfio: Error: trigger event_notifier_init failed ");
+ return NULL;
+ }
+
+ QLIST_INSERT_HEAD(&vdev->intp_list, intp, next);
+ return intp;
+}
+
+/**
+ * vfio_set_trigger_eventfd - set VFIO eventfd handling
+ *
+ * @intp: IRQ struct handle
+ * @handler: handler to be called on eventfd signaling
+ *
+ * Setup VFIO signaling and attach an optional user-side handler
+ * to the eventfd
+ */
+static int vfio_set_trigger_eventfd(VFIOINTp *intp,
+ eventfd_user_side_handler_t handler)
+{
+ VFIODevice *vbasedev = &intp->vdev->vbasedev;
+ struct vfio_irq_set *irq_set;
+ int argsz, ret;
+ int32_t *pfd;
+
+ argsz = sizeof(*irq_set) + sizeof(*pfd);
+ irq_set = g_malloc0(argsz);
+ irq_set->argsz = argsz;
+ irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER;
+ irq_set->index = intp->pin;
+ irq_set->start = 0;
+ irq_set->count = 1;
+ pfd = (int32_t *)&irq_set->data;
+ *pfd = event_notifier_get_fd(&intp->interrupt);
+ qemu_set_fd_handler(*pfd, (IOHandler *)handler, NULL, intp);
+ ret = ioctl(vbasedev->fd, VFIO_DEVICE_SET_IRQS, irq_set);
+ g_free(irq_set);
+ if (ret < 0) {
+ error_report("vfio: Failed to set trigger eventfd: %m");
+ qemu_set_fd_handler(*pfd, NULL, NULL, NULL);
+ }
+ return ret;
+}
+
+/*
+ * Functions only used when eventfds are handled on user-side
+ * ie. without irqfd
+ */
+
+/**
+ * vfio_mmap_set_enabled - enable/disable the fast path mode
+ * @vdev: the VFIO platform device
+ * @enabled: the target mmap state
+ *
+ * enabled = true ~ fast path = MMIO region is mmaped (no KVM TRAP);
+ * enabled = false ~ slow path = MMIO region is trapped and region callbacks
+ * are called; slow path enables to trap the device IRQ status register reset
+*/
+
+static void vfio_mmap_set_enabled(VFIOPlatformDevice *vdev, bool enabled)
+{
+ int i;
+
+ trace_vfio_platform_mmap_set_enabled(enabled);
+
+ for (i = 0; i < vdev->vbasedev.num_regions; i++) {
+ VFIORegion *region = vdev->regions[i];
+
+ memory_region_set_enabled(&region->mmap_mem, enabled);
+ }
+}
+
+/**
+ * vfio_intp_mmap_enable - timer function, restores the fast path
+ * if there is no more active IRQ
+ * @opaque: actually points to the VFIO platform device
+ *
+ * Called on mmap timer timout, this function checks whether the
+ * IRQ is still active and if not, restores the fast path.
+ * by construction a single eventfd is handled at a time.
+ * if the IRQ is still active, the timer is re-programmed.
+ */
+static void vfio_intp_mmap_enable(void *opaque)
+{
+ VFIOINTp *tmp;
+ VFIOPlatformDevice *vdev = (VFIOPlatformDevice *)opaque;
+
+ qemu_mutex_lock(&vdev->intp_mutex);
+ QLIST_FOREACH(tmp, &vdev->intp_list, next) {
+ if (tmp->state == VFIO_IRQ_ACTIVE) {
+ trace_vfio_platform_intp_mmap_enable(tmp->pin);
+ /* re-program the timer to check active status later */
+ timer_mod(vdev->mmap_timer,
+ qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
+ vdev->mmap_timeout);
+ qemu_mutex_unlock(&vdev->intp_mutex);
+ return;
+ }
+ }
+ vfio_mmap_set_enabled(vdev, true);
+ qemu_mutex_unlock(&vdev->intp_mutex);
+}
+
+/**
+ * vfio_intp_inject_pending_lockheld - Injects a pending IRQ
+ * @opaque: opaque pointer, in practice the VFIOINTp handle
+ *
+ * The function is called on a previous IRQ completion, from
+ * vfio_platform_eoi, while the intp_mutex is locked.
+ * Also in such situation, the slow path already is set and
+ * the mmap timer was already programmed.
+ */
+static void vfio_intp_inject_pending_lockheld(VFIOINTp *intp)
+{
+ trace_vfio_platform_intp_inject_pending_lockheld(intp->pin,
+ event_notifier_get_fd(&intp->interrupt));
+
+ intp->state = VFIO_IRQ_ACTIVE;
+
+ /* trigger the virtual IRQ */
+ qemu_set_irq(intp->qemuirq, 1);
+}
+
+/**
+ * vfio_intp_interrupt - The user-side eventfd handler
+ * @opaque: opaque pointer which in practice is the VFIOINTp handle
+ *
+ * the function is entered in event handler context:
+ * the vIRQ is injected into the guest if there is no other active
+ * or pending IRQ.
+ */
+static void vfio_intp_interrupt(VFIOINTp *intp)
+{
+ int ret;
+ VFIOINTp *tmp;
+ VFIOPlatformDevice *vdev = intp->vdev;
+ bool delay_handling = false;
+
+ qemu_mutex_lock(&vdev->intp_mutex);
+ if (intp->state == VFIO_IRQ_INACTIVE) {
+ QLIST_FOREACH(tmp, &vdev->intp_list, next) {
+ if (tmp->state == VFIO_IRQ_ACTIVE ||
+ tmp->state == VFIO_IRQ_PENDING) {
+ delay_handling = true;
+ break;
+ }
+ }
+ }
+ if (delay_handling) {
+ /*
+ * the new IRQ gets a pending status and is pushed in
+ * the pending queue
+ */
+ intp->state = VFIO_IRQ_PENDING;
+ trace_vfio_intp_interrupt_set_pending(intp->pin);
+ QSIMPLEQ_INSERT_TAIL(&vdev->pending_intp_queue,
+ intp, pqnext);
+ ret = event_notifier_test_and_clear(&intp->interrupt);
+ qemu_mutex_unlock(&vdev->intp_mutex);
+ return;
+ }
+
+ trace_vfio_platform_intp_interrupt(intp->pin,
+ event_notifier_get_fd(&intp->interrupt));
+
+ ret = event_notifier_test_and_clear(&intp->interrupt);
+ if (!ret) {
+ error_report("Error when clearing fd=%d (ret = %d)\n",
+ event_notifier_get_fd(&intp->interrupt), ret);
+ }
+
+ intp->state = VFIO_IRQ_ACTIVE;
+
+ /* sets slow path */
+ vfio_mmap_set_enabled(vdev, false);
+
+ /* trigger the virtual IRQ */
+ qemu_set_irq(intp->qemuirq, 1);
+
+ /*
+ * Schedule the mmap timer which will restore fastpath when no IRQ
+ * is active anymore
+ */
+ if (vdev->mmap_timeout) {
+ timer_mod(vdev->mmap_timer,
+ qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
+ vdev->mmap_timeout);
+ }
+ qemu_mutex_unlock(&vdev->intp_mutex);
+}
+
+/**
+ * vfio_platform_eoi - IRQ completion routine
+ * @vbasedev: the VFIO device handle
+ *
+ * De-asserts the active virtual IRQ and unmasks the physical IRQ
+ * (effective for level sensitive IRQ auto-masked by the VFIO driver).
+ * Then it handles next pending IRQ if any.
+ * eoi function is called on the first access to any MMIO region
+ * after an IRQ was triggered, trapped since slow path was set.
+ * It is assumed this access corresponds to the IRQ status
+ * register reset. With such a mechanism, a single IRQ can be
+ * handled at a time since there is no way to know which IRQ
+ * was completed by the guest (we would need additional details
+ * about the IRQ status register mask).
+ */
+static void vfio_platform_eoi(VFIODevice *vbasedev)
+{
+ VFIOINTp *intp;
+ VFIOPlatformDevice *vdev =
+ container_of(vbasedev, VFIOPlatformDevice, vbasedev);
+
+ qemu_mutex_lock(&vdev->intp_mutex);
+ QLIST_FOREACH(intp, &vdev->intp_list, next) {
+ if (intp->state == VFIO_IRQ_ACTIVE) {
+ trace_vfio_platform_eoi(intp->pin,
+ event_notifier_get_fd(&intp->interrupt));
+ intp->state = VFIO_IRQ_INACTIVE;
+
+ /* deassert the virtual IRQ */
+ qemu_set_irq(intp->qemuirq, 0);
+
+ if (intp->flags & VFIO_IRQ_INFO_AUTOMASKED) {
+ /* unmasks the physical level-sensitive IRQ */
+ vfio_unmask_single_irqindex(vbasedev, intp->pin);
+ }
+
+ /* a single IRQ can be active at a time */
+ break;
+ }
+ }
+ /* in case there are pending IRQs, handle the first one */
+ if (!QSIMPLEQ_EMPTY(&vdev->pending_intp_queue)) {
+ intp = QSIMPLEQ_FIRST(&vdev->pending_intp_queue);
+ vfio_intp_inject_pending_lockheld(intp);
+ QSIMPLEQ_REMOVE_HEAD(&vdev->pending_intp_queue, pqnext);
+ }
+ qemu_mutex_unlock(&vdev->intp_mutex);
+}
+
+/**
+ * vfio_start_eventfd_injection - starts the virtual IRQ injection using
+ * user-side handled eventfds
+ * @intp: the IRQ struct pointer
+ */
+
+static int vfio_start_eventfd_injection(VFIOINTp *intp)
+{
+ int ret;
+
+ ret = vfio_set_trigger_eventfd(intp, vfio_intp_interrupt);
+ if (ret) {
+ error_report("vfio: Error: Failed to pass IRQ fd to the driver: %m");
+ }
+ return ret;
+}
+
/* VFIO skeleton */

static void vfio_platform_compute_needs_reset(VFIODevice *vbasedev)
@@ -41,12 +330,13 @@ static int vfio_platform_hot_reset_multi(VFIODevice *vbasedev)

/**
* vfio_populate_device - Allocate and populate MMIO region
- * structs according to driver returned information
+ * and IRQ structs according to driver returned information
* @vbasedev: the VFIO device handle
*
*/
static int vfio_populate_device(VFIODevice *vbasedev)
{
+ VFIOINTp *intp, *tmp;
int i, ret = -1;
VFIOPlatformDevice *vdev =
container_of(vbasedev, VFIOPlatformDevice, vbasedev);
@@ -84,7 +374,38 @@ static int vfio_populate_device(VFIODevice *vbasedev)
(unsigned long)ptr->fd_offset);
}

+ vdev->mmap_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
+ vfio_intp_mmap_enable, vdev);
+
+ QSIMPLEQ_INIT(&vdev->pending_intp_queue);
+
+ for (i = 0; i < vbasedev->num_irqs; i++) {
+ struct vfio_irq_info irq = { .argsz = sizeof(irq) };
+
+ irq.index = i;
+ ret = ioctl(vbasedev->fd, VFIO_DEVICE_GET_IRQ_INFO, &irq);
+ if (ret) {
+ error_printf("vfio: error getting device %s irq info",
+ vbasedev->name);
+ goto irq_err;
+ } else {
+ trace_vfio_platform_populate_interrupts(irq.index,
+ irq.count,
+ irq.flags);
+ intp = vfio_init_intp(vbasedev, irq);
+ if (!intp) {
+ error_report("vfio: Error installing IRQ %d up", i);
+ goto irq_err;
+ }
+ }
+ }
return 0;
+irq_err:
+ timer_del(vdev->mmap_timer);
+ QLIST_FOREACH_SAFE(intp, &vdev->intp_list, next, tmp) {
+ QLIST_REMOVE(intp, next);
+ g_free(intp);
+ }
reg_error:
for (i = 0; i < vbasedev->num_regions; i++) {
g_free(vdev->regions[i]);
@@ -97,6 +418,7 @@ reg_error:
static VFIODeviceOps vfio_platform_ops = {
.vfio_compute_needs_reset = vfio_platform_compute_needs_reset,
.vfio_hot_reset_multi = vfio_platform_hot_reset_multi,
+ .vfio_eoi = vfio_platform_eoi,
};

/**
@@ -228,6 +550,7 @@ static void vfio_platform_realize(DeviceState *dev, Error **errp)
VFIOPlatformDevice *vdev = VFIO_PLATFORM_DEVICE(dev);
SysBusDevice *sbdev = SYS_BUS_DEVICE(dev);
VFIODevice *vbasedev = &vdev->vbasedev;
+ VFIOINTp *intp;
int i, ret;

vbasedev->type = VFIO_DEVICE_TYPE_PLATFORM;
@@ -246,6 +569,10 @@ static void vfio_platform_realize(DeviceState *dev, Error **errp)
vfio_map_region(vdev, i);
sysbus_init_mmio(sbdev, &vdev->regions[i]->mem);
}
+
+ QLIST_FOREACH(intp, &vdev->intp_list, next) {
+ vfio_start_eventfd_injection(intp);
+ }
}

static const VMStateDescription vfio_platform_vmstate = {
@@ -256,6 +583,8 @@ static const VMStateDescription vfio_platform_vmstate = {
static Property vfio_platform_dev_properties[] = {
DEFINE_PROP_STRING("host", VFIOPlatformDevice, vbasedev.name),
DEFINE_PROP_BOOL("x-mmap", VFIOPlatformDevice, vbasedev.allow_mmap, true),
+ DEFINE_PROP_UINT32("mmap-timeout-ms", VFIOPlatformDevice,
+ mmap_timeout, 1100),
DEFINE_PROP_END_OF_LIST(),
};

diff --git a/include/hw/vfio/vfio-platform.h b/include/hw/vfio/vfio-platform.h
index 338f0c6..26b2ad6 100644
--- a/include/hw/vfio/vfio-platform.h
+++ b/include/hw/vfio/vfio-platform.h
@@ -18,14 +18,45 @@

#include "hw/sysbus.h"
#include "hw/vfio/vfio-common.h"
+#include "qemu/event_notifier.h"
+#include "qemu/queue.h"
+#include "hw/irq.h"

#define TYPE_VFIO_PLATFORM "vfio-platform"

+enum {
+ VFIO_IRQ_INACTIVE = 0,
+ VFIO_IRQ_PENDING = 1,
+ VFIO_IRQ_ACTIVE = 2,
+ /* VFIO_IRQ_ACTIVE_AND_PENDING cannot happen with VFIO */
+};
+
+typedef struct VFIOINTp {
+ QLIST_ENTRY(VFIOINTp) next; /* entry for IRQ list */
+ QSIMPLEQ_ENTRY(VFIOINTp) pqnext; /* entry for pending IRQ queue */
+ EventNotifier interrupt; /* eventfd triggered on interrupt */
+ EventNotifier unmask; /* eventfd for unmask on QEMU bypass */
+ qemu_irq qemuirq;
+ struct VFIOPlatformDevice *vdev; /* back pointer to device */
+ int state; /* inactive, pending, active */
+ uint8_t pin; /* index */
+ uint32_t flags; /* IRQ info flags */
+} VFIOINTp;
+
+/* function type for user side eventfd handler */
+typedef void (*eventfd_user_side_handler_t)(VFIOINTp *intp);
+
typedef struct VFIOPlatformDevice {
SysBusDevice sbdev;
VFIODevice vbasedev; /* not a QOM object */
VFIORegion **regions;
+ QLIST_HEAD(, VFIOINTp) intp_list; /* list of IRQs */
+ /* queue of pending IRQs */
+ QSIMPLEQ_HEAD(pending_intp_queue, VFIOINTp) pending_intp_queue;
char *compat; /* compatibility string */
+ uint32_t mmap_timeout; /* delay to re-enable mmaps after interrupt */
+ QEMUTimer *mmap_timer; /* allows fast-path resume after IRQ hit */
+ QemuMutex intp_mutex; /* protect the intp_list IRQ state */
} VFIOPlatformDevice;

typedef struct VFIOPlatformDeviceClass {
diff --git a/trace-events b/trace-events
index 2ccc822..ed8ed90 100644
--- a/trace-events
+++ b/trace-events
@@ -1564,6 +1564,13 @@ vfio_put_base_device(int fd) "close vdev->fd=%d"
vfio_platform_populate_regions(int region_index, unsigned long flag, unsigned long size, int fd, unsigned long offset) "- region %d flags = 0x%lx, size = 0x%lx, fd= %d, offset = 0x%lx"
vfio_platform_base_device_init(char *name, int groupid) "%s belongs to group #%d"
vfio_platform_realize(char *name, char *compat) "vfio device %s, compat = %s"
+vfio_platform_eoi(int pin, int fd) "EOI IRQ pin %d (fd=%d)"
+vfio_platform_mmap_set_enabled(bool enabled) "fast path = %d"
+vfio_platform_intp_mmap_enable(int pin) "IRQ #%d still active, stay in slow path"
+vfio_platform_intp_interrupt(int pin, int fd) "Inject IRQ #%d (fd = %d)"
+vfio_platform_intp_inject_pending_lockheld(int pin, int fd) "Inject pending IRQ #%d (fd = %d)"
+vfio_platform_populate_interrupts(int pin, int count, int flags) "- IRQ index %d: count %d, flags=0x%x"
+vfio_intp_interrupt_set_pending(int index) "irq %d is set PENDING"

#hw/acpi/memory_hotplug.c
mhp_acpi_invalid_slot_selected(uint32_t slot) "0x%"PRIx32
--
1.8.3.2