[RFC PATCH 1/2] Add a new register offset let interrupt reason available

[john.liuli]

From: Li Liu john.li...@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.li...@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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Re: [RFC PATCH 1/2] Add a new register offset let interrupt reason available

[Michael S. Tsirkin]

On Sat, Oct 25, 2014 at 04:24:53PM +0800, john.liuli wrote:
 From: Li Liu john.li...@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.li...@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);
 +

What happens to existing devices?
then might not expect writes at this address.

   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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