[Minios-devel] [UNIKRAFT PATCH 09/17] plat/xen/drivers/blk: Enable/disable interrupts for queues

[Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>]

This patch introduces support for the user to enable/disable interrupts
on queues.

Signed-off-by: Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>
---
 plat/xen/drivers/blk/blkfront.c | 83 +++++++++++++++++++++++++++++++++++++++++
 plat/xen/drivers/blk/blkfront.h |  2 +
 2 files changed, 85 insertions(+)

diff --git a/plat/xen/drivers/blk/blkfront.c b/plat/xen/drivers/blk/blkfront.c
index 9ccd2113..c65267f0 100644
--- a/plat/xen/drivers/blk/blkfront.c
+++ b/plat/xen/drivers/blk/blkfront.c
@@ -41,12 +41,19 @@
 #include <uk/essentials.h>
 #include <uk/arch/limits.h>
 #include <uk/blkdev_driver.h>
+#include <xen-x86/mm.h>
+#include <xen-x86/mm_pv.h>
 #include <xenbus/xenbus.h>
 #include "blkfront.h"
 #include "blkfront_xb.h"
 
 #define DRIVER_NAME            "xen-blkfront"
 
+/* TODO Same interrupt macros we use in virtio-blk */
+#define BLKFRONT_INTR_EN             (1 << 0)
+#define BLKFRONT_INTR_EN_MASK        (1)
+#define BLKFRONT_INTR_USR_EN         (1 << 1)
+#define BLKFRONT_INTR_USR_EN_MASK    (2)
 
 /* Get blkfront_dev* which contains blkdev */
 #define to_blkfront(blkdev) \
@@ -55,6 +62,22 @@
 static struct uk_alloc *drv_allocator;
 
 
+/* Returns 1 if more responses available */
+static int blkfront_xen_ring_intr_enable(struct uk_blkdev_queue *queue)
+{
+       int more;
+
+       /* Check if there are no more responses enabled */
+       RING_FINAL_CHECK_FOR_RESPONSES(&queue->ring, more);
+       if (!more) {
+               /* No more responses, we can enable interrupts */
+               queue->intr_enabled |= BLKFRONT_INTR_EN;
+               unmask_evtchn(queue->evtchn);
+       }
+
+       return (more > 0);
+}
+
 static int blkfront_ring_init(struct uk_blkdev_queue *queue)
 {
        struct blkif_sring *sring = NULL;
@@ -98,6 +121,11 @@ static void blkfront_handler(evtchn_port_t port __unused,
 
        UK_ASSERT(arg);
        queue = (struct uk_blkdev_queue *)arg;
+
+       /* Disable the interrupt for the ring */
+       queue->intr_enabled &= ~(BLKFRONT_INTR_EN);
+       mask_evtchn(queue->evtchn);
+
        uk_blkdev_drv_queue_event(&queue->dev->blkdev, queue->queue_id);
 }
 
@@ -122,6 +150,7 @@ static struct uk_blkdev_queue *blkfront_queue_setup(struct 
uk_blkdev *blkdev,
        queue->a = queue_conf->a;
        queue->queue_id = queue_id;
        queue->dev = dev;
+       queue->intr_enabled = 0;
        err = blkfront_ring_init(queue);
        if (err) {
                uk_pr_err("Failed to init ring: %d.\n", err);
@@ -164,6 +193,58 @@ static int blkfront_queue_release(struct uk_blkdev *blkdev,
        unbind_evtchn(queue->evtchn);
        blkfront_ring_fini(queue);
 
+
+static int blkfront_queue_intr_enable(struct uk_blkdev *blkdev,
+                                            uint16_t queue_id)
+{
+       struct blkfront_dev *dev;
+       struct uk_blkdev_queue *queue;
+       int rc = 0;
+
+       UK_ASSERT(blkdev);
+       dev = to_blkfront(blkdev);
+       if (queue_id >= dev->nb_queues) {
+               uk_pr_err("Invalid queue identifier: %"__PRIu16"\n", queue_id);
+               return -EINVAL;
+       }
+
+       queue = &dev->queues[queue_id];
+       /* If the interrupt is enabled */
+       if (queue->intr_enabled & BLKFRONT_INTR_EN)
+               return 0;
+
+       /**
+        * Enable the user configuration bit. This would cause the interrupt to
+        * be enabled automatically if the interrupt could not be enabled now
+        * due to data in the queue.
+        */
+       queue->intr_enabled = BLKFRONT_INTR_USR_EN;
+       rc = blkfront_xen_ring_intr_enable(queue);
+       if (!rc)
+               queue->intr_enabled |= BLKFRONT_INTR_EN;
+
+       return rc;
+}
+
+static int blkfront_queue_intr_disable(struct uk_blkdev *blkdev,
+                                            uint16_t queue_id)
+{
+       struct blkfront_dev *dev;
+       struct uk_blkdev_queue *queue;
+
+       UK_ASSERT(blkdev);
+
+       dev = to_blkfront(blkdev);
+       if (queue_id >= dev->nb_queues) {
+               uk_pr_err("Invalid queue identifier: %"__PRIu16"\n", queue_id);
+               return -EINVAL;
+       }
+
+       queue = &dev->queues[queue_id];
+
+       queue->intr_enabled &= ~(BLKFRONT_INTR_USR_EN | BLKFRONT_INTR_EN);
+       mask_evtchn(queue->evtchn);
+
        return 0;
 }
 
@@ -255,6 +336,8 @@ static const struct uk_blkdev_ops blkfront_ops = {
        .queue_setup = blkfront_queue_setup,
        .queue_release = blkfront_queue_release,
        .dev_close = blkfront_close,
+       .queue_intr_enable = blkfront_queue_intr_enable,
+       .queue_intr_disable = blkfront_queue_intr_disable,
 };
 
 /**
diff --git a/plat/xen/drivers/blk/blkfront.h b/plat/xen/drivers/blk/blkfront.h
index 656f7845..bf6d231e 100644
--- a/plat/xen/drivers/blk/blkfront.h
+++ b/plat/xen/drivers/blk/blkfront.h
@@ -62,6 +62,8 @@ struct uk_blkdev_queue {
        struct uk_alloc *a;
        /* The libukblkdev queue identifier */
        uint16_t queue_id;
+       /* The flag to interrupt on the queue */
+       int intr_enabled;
        /* Reference to the Blkfront Device */
        struct blkfront_dev *dev;
 };
-- 
2.11.0


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