blk-mq: provide a default queue mapping for virtio device

Similar to the PCI version, just calling into virtio instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/block/Kconfig b/block/Kconfig
index 8bf114a..3523b4f 100644 (file)
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -165,4 +165,9 @@ config BLK_MQ_PCI
        depends on BLOCK && PCI
        default y
 
+config BLK_MQ_VIRTIO
+       bool
+       depends on BLOCK && VIRTIO
+       default y
+
 source block/Kconfig.iosched

diff --git a/block/Makefile b/block/Makefile
index a827f98..6069194 100644 (file)
--- a/block/Makefile
+++ b/block/Makefile
@@ -23,5 +23,6 @@ obj-$(CONFIG_BLOCK_COMPAT)    += compat_ioctl.o
 obj-$(CONFIG_BLK_CMDLINE_PARSER)       += cmdline-parser.o
 obj-$(CONFIG_BLK_DEV_INTEGRITY) += bio-integrity.o blk-integrity.o t10-pi.o
 obj-$(CONFIG_BLK_MQ_PCI)       += blk-mq-pci.o
+obj-$(CONFIG_BLK_MQ_VIRTIO)    += blk-mq-virtio.o
 obj-$(CONFIG_BLK_DEV_ZONED)    += blk-zoned.o
 obj-$(CONFIG_BLK_WBT)          += blk-wbt.o

diff --git a/block/blk-mq-virtio.c b/block/blk-mq-virtio.c
new file mode 100644 (file)
index 0000000..c3afbca
--- /dev/null
+++ b/block/blk-mq-virtio.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2016 Christoph Hellwig.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/device.h>
+#include <linux/blk-mq.h>
+#include <linux/blk-mq-virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/module.h>
+#include "blk-mq.h"
+
+/**
+ * blk_mq_virtio_map_queues - provide a default queue mapping for virtio device
+ * @set:       tagset to provide the mapping for
+ * @vdev:      virtio device associated with @set.
+ * @first_vec: first interrupt vectors to use for queues (usually 0)
+ *
+ * This function assumes the virtio device @vdev has at least as many available
+ * interrupt vetors as @set has queues.  It will then queuery the vector
+ * corresponding to each queue for it's affinity mask and built queue mapping
+ * that maps a queue to the CPUs that have irq affinity for the corresponding
+ * vector.
+ */
+int blk_mq_virtio_map_queues(struct blk_mq_tag_set *set,
+               struct virtio_device *vdev, int first_vec)
+{
+       const struct cpumask *mask;
+       unsigned int queue, cpu;
+
+       if (!vdev->config->get_vq_affinity)
+               goto fallback;
+
+       for (queue = 0; queue < set->nr_hw_queues; queue++) {
+               mask = vdev->config->get_vq_affinity(vdev, first_vec + queue);
+               if (!mask)
+                       goto fallback;
+
+               for_each_cpu(cpu, mask)
+                       set->mq_map[cpu] = queue;
+       }
+
+       return 0;
+fallback:
+       return blk_mq_map_queues(set);
+}
+EXPORT_SYMBOL_GPL(blk_mq_virtio_map_queues);

diff --git a/include/linux/blk-mq-virtio.h b/include/linux/blk-mq-virtio.h
new file mode 100644 (file)
index 0000000..b1ef6e1
--- /dev/null
+++ b/include/linux/blk-mq-virtio.h
@@ -0,0 +1,10 @@
+#ifndef _LINUX_BLK_MQ_VIRTIO_H
+#define _LINUX_BLK_MQ_VIRTIO_H
+
+struct blk_mq_tag_set;
+struct virtio_device;
+
+int blk_mq_virtio_map_queues(struct blk_mq_tag_set *set,
+               struct virtio_device *vdev, int first_vec);
+
+#endif /* _LINUX_BLK_MQ_VIRTIO_H */