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Subject[RFC PATCH 1/2] Add a new register offset let interrupt reason available
Date
From: Li Liu <john.liuli@huawei.com>

Add a new register offset VIRTIO_MMIO_ISRMEM which help to
estblish a shared memory region between virtio-mmio driver
and qemu with two purposes:

1.Guest virtio-mmio driver can get the interrupt reason.
2.Check irqfd enabled or not to register different irq handler.

Signed-off-by: Li Liu <john.liuli@huawei.com>
---
drivers/virtio/virtio_mmio.c | 21 ++++++++++++++++++++-
include/linux/virtio_mmio.h | 3 +++
2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index ef9a165..28ddb55 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -122,6 +122,8 @@ struct virtio_mmio_device {
/* a list of queues so we can dispatch IRQs */
spinlock_t lock;
struct list_head virtqueues;
+
+ uint8_t *isr_mem;
};

struct virtio_mmio_vq_info {
@@ -443,6 +445,7 @@ static int virtio_mmio_probe(struct platform_device *pdev)
struct virtio_mmio_device *vm_dev;
struct resource *mem;
unsigned long magic;
+ int err;

mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!mem)
@@ -481,6 +484,15 @@ static int virtio_mmio_probe(struct platform_device *pdev)
return -ENXIO;
}

+ vm_dev->isr_mem = alloc_pages_exact(PAGE_SIZE, GFP_KERNEL|__GFP_ZERO);
+ if (vm_dev->isr_mem == NULL) {
+ dev_err(&pdev->dev, "Allocate isr memory failed!\n");
+ return -ENOMEM;
+ }
+
+ writel(virt_to_phys(vm_dev->isr_mem),
+ vm_dev->base + VIRTIO_MMIO_ISRMEM);
+
vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);

@@ -488,13 +500,20 @@ static int virtio_mmio_probe(struct platform_device *pdev)

platform_set_drvdata(pdev, vm_dev);

- return register_virtio_device(&vm_dev->vdev);
+ err = register_virtio_device(&vm_dev->vdev);
+ if (err) {
+ free_pages_exact(vm_dev->isr_mem, PAGE_SIZE);
+ vm_dev->isr_mem = NULL;
+ }
+
+ return err;
}

static int virtio_mmio_remove(struct platform_device *pdev)
{
struct virtio_mmio_device *vm_dev = platform_get_drvdata(pdev);

+ free_pages_exact(vm_dev->isr_mem, PAGE_SIZE);
unregister_virtio_device(&vm_dev->vdev);

return 0;
diff --git a/include/linux/virtio_mmio.h b/include/linux/virtio_mmio.h
index 5c7b6f0..b1e3ec7 100644
--- a/include/linux/virtio_mmio.h
+++ b/include/linux/virtio_mmio.h
@@ -95,6 +95,9 @@
/* Device status register - Read Write */
#define VIRTIO_MMIO_STATUS 0x070

+/* Allocate ISRMEM for interrupt reason - Write Only */
+#define VIRTIO_MMIO_ISRMEM 0x080
+
/* The config space is defined by each driver as
* the per-driver configuration space - Read Write */
#define VIRTIO_MMIO_CONFIG 0x100
--
1.7.9.5



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