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Subject[PATCH] vfio: Add an ioctl to reset the device
Date
When using VFIO to assign a device to a guest, we want to make sure
the device is quiesced on VM reset to stop all DMA within the guest
mapped memory. Add an ioctl which just calls pci_reset_function()
and returns whether it succeeds.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
We've recently needed to add this functionality for current KVM
based device assignment, VFIO should provide a way to do this too.
An example of it being used in the Qemu VFIO driver can be found
here:

https://github.com/awilliam/qemu-vfio/blob/vfio/hw/vfio.c

drivers/vfio/vfio_main.c | 4 ++++
include/linux/vfio.h | 3 +++
2 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 7e427fc..b9bb692 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -490,6 +490,10 @@ static long vfio_unl_ioctl(struct file *filep,
ret = vfio_irq_eoi_eventfd(vdev, fd);
break;

+ case VFIO_RESET_FUNCTION:
+ ret = pci_reset_function(vdev->pdev);
+ break;
+
default:
return -EINVAL;
}
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index f07d8fe..47d9bb9 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -215,6 +215,9 @@ struct vfio_dma_map {
/* Re-enable INTx via eventfd */
#define VFIO_IRQ_EOI_EVENTFD _IOW(';', 110, int)

+/* Reset PCI function */
+#define VFIO_RESET_FUNCTION _IO(';', 111)
+
/*
* Reads, writes, and mmaps determine which PCI BAR (or config space)
* from the high level bits of the file offset


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