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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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