[RFC PATCH v4 4/4] virtio-mmio: wire up noirq system sleep PM callbacks

[Sungho Bae <baver.bae@gmail.com>]

From: Sungho Bae <baver.bae@lge.com>

Add noirq system-sleep PM support to the virtio-mmio transport.

This change wires noirq freeze/restore callbacks into virtio-mmio and
hooks queue reset/reactivation into the transport config ops so virtqueues
can be reinitialized and reused across suspend/resume.

For legacy (v1) devices, keep GUEST_PAGE_SIZE programming aligned with the
noirq restore path while avoiding duplicate programming in normal restore.

This enables virtio-mmio based devices to participate safely in the noirq
PM phase, which is required for early-restore users.

Signed-off-by: Sungho Bae <baver.bae@lge.com>
---
 drivers/virtio/virtio_mmio.c | 134 ++++++++++++++++++++++++-----------
 1 file changed, 94 insertions(+), 40 deletions(-)

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 595c2274fbb5..1cd262f9f8b6 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -336,6 +336,75 @@ static void vm_del_vqs(struct virtio_device *vdev)
 	free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev);
 }
 
+static int vm_active_vq(struct virtio_device *vdev, struct virtqueue *vq)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	int q_num = virtqueue_get_vring_size(vq);
+
+	writel(q_num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
+	if (vm_dev->version == 1) {
+		u64 q_pfn = virtqueue_get_desc_addr(vq) >> PAGE_SHIFT;
+
+		/*
+		 * virtio-mmio v1 uses a 32bit QUEUE PFN. If we have something
+		 * that doesn't fit in 32bit, fail the setup rather than
+		 * pretending to be successful.
+		 */
+		if (q_pfn >> 32) {
+			dev_err(&vdev->dev,
+				"platform bug: legacy virtio-mmio must not be used with RAM above 0x%llxGB\n",
+				0x1ULL << (32 + PAGE_SHIFT - 30));
+			return -E2BIG;
+		}
+
+		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
+		writel(q_pfn, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
+	} else {
+		u64 addr;
+
+		addr = virtqueue_get_desc_addr(vq);
+		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
+		writel((u32)(addr >> 32),
+				vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
+
+		addr = virtqueue_get_avail_addr(vq);
+		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
+		writel((u32)(addr >> 32),
+				vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);
+
+		addr = virtqueue_get_used_addr(vq);
+		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_USED_LOW);
+		writel((u32)(addr >> 32),
+				vm_dev->base + VIRTIO_MMIO_QUEUE_USED_HIGH);
+
+		writel(1, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
+	}
+
+	return 0;
+}
+
+static int vm_reset_vqs(struct virtio_device *vdev)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	struct virtqueue *vq;
+	int err;
+
+	virtio_device_for_each_vq(vdev, vq) {
+		/* Re-initialize vring state */
+		virtqueue_reinit_vring(vq);
+
+		/* Select the queue we're interested in */
+		writel(vq->index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
+
+		/* Activate the queue */
+		err = vm_active_vq(vdev, vq);
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+
 static void vm_synchronize_cbs(struct virtio_device *vdev)
 {
 	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
@@ -388,45 +457,9 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned int in
 	vq->num_max = num;
 
 	/* Activate the queue */
-	writel(virtqueue_get_vring_size(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
-	if (vm_dev->version == 1) {
-		u64 q_pfn = virtqueue_get_desc_addr(vq) >> PAGE_SHIFT;
-
-		/*
-		 * virtio-mmio v1 uses a 32bit QUEUE PFN. If we have something
-		 * that doesn't fit in 32bit, fail the setup rather than
-		 * pretending to be successful.
-		 */
-		if (q_pfn >> 32) {
-			dev_err(&vdev->dev,
-				"platform bug: legacy virtio-mmio must not be used with RAM above 0x%llxGB\n",
-				0x1ULL << (32 + PAGE_SHIFT - 30));
-			err = -E2BIG;
-			goto error_bad_pfn;
-		}
-
-		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
-		writel(q_pfn, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
-	} else {
-		u64 addr;
-
-		addr = virtqueue_get_desc_addr(vq);
-		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
-		writel((u32)(addr >> 32),
-				vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
-
-		addr = virtqueue_get_avail_addr(vq);
-		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
-		writel((u32)(addr >> 32),
-				vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);
-
-		addr = virtqueue_get_used_addr(vq);
-		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_USED_LOW);
-		writel((u32)(addr >> 32),
-				vm_dev->base + VIRTIO_MMIO_QUEUE_USED_HIGH);
-
-		writel(1, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
-	}
+	err = vm_active_vq(vdev, vq);
+	if (err < 0)
+		goto error_bad_pfn;
 
 	return vq;
 
@@ -528,11 +561,13 @@ static const struct virtio_config_ops virtio_mmio_config_ops = {
 	.reset		= vm_reset,
 	.find_vqs	= vm_find_vqs,
 	.del_vqs	= vm_del_vqs,
+	.reset_vqs	= vm_reset_vqs,
 	.get_features	= vm_get_features,
 	.finalize_features = vm_finalize_features,
 	.bus_name	= vm_bus_name,
 	.get_shm_region = vm_get_shm_region,
 	.synchronize_cbs = vm_synchronize_cbs,
+	.noirq_safe	= true,
 };
 
 #ifdef CONFIG_PM_SLEEP
@@ -547,14 +582,33 @@ static int virtio_mmio_restore(struct device *dev)
 {
 	struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
 
-	if (vm_dev->version == 1)
+	if (vm_dev->version == 1 && !vm_dev->vdev.noirq_restore_done)
 		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
 
 	return virtio_device_restore(&vm_dev->vdev);
 }
 
+static int virtio_mmio_freeze_noirq(struct device *dev)
+{
+	struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
+
+	return virtio_device_freeze_noirq(&vm_dev->vdev);
+}
+
+static int virtio_mmio_restore_noirq(struct device *dev)
+{
+	struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
+
+	if (vm_dev->version == 1)
+		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
+
+	return virtio_device_restore_noirq(&vm_dev->vdev);
+}
+
 static const struct dev_pm_ops virtio_mmio_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(virtio_mmio_freeze, virtio_mmio_restore)
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(virtio_mmio_freeze_noirq,
+				      virtio_mmio_restore_noirq)
 };
 #endif
 
-- 
2.43.0