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[Qemu-devel] Re: [SeaBIOS] [PATCH] virtio: Clear interrupt status regist
From: |
Gleb Natapov |
Subject: |
[Qemu-devel] Re: [SeaBIOS] [PATCH] virtio: Clear interrupt status register in virtio-blk |
Date: |
Thu, 8 Jul 2010 10:19:53 +0300 |
On Wed, Jul 07, 2010 at 01:34:22PM +0100, Stefan Hajnoczi wrote:
> The VRING_AVAIL_F_NO_INTERRUPT flag is a hint that interrupts should be
> suppressed. It does not guarantee that interrupts will not be raised.
> Therefore, make sure to clear the interrupt after each virtio-blk read.
> This avoids a stuck interrupt interfering with the OS loaded later in
> the boot process.
>
> Signed-off-by: Stefan Hajnoczi <address@hidden>
Acked-by: Gleb Natapov <address@hidden>
> ---
> src/virtio-blk.c | 6 ++++++
> src/virtio-pci.h | 4 ++++
> 2 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/src/virtio-blk.c b/src/virtio-blk.c
> index 16d9ad8..74af488 100644
> --- a/src/virtio-blk.c
> +++ b/src/virtio-blk.c
> @@ -62,6 +62,12 @@ virtio_blk_read(struct disk_op_s *op)
>
> /* Reclaim virtqueue element */
> vring_get_buf(vq, NULL);
> +
> + /* Clear interrupt status register. Avoid leaving interrupts stuck if
> + * VRING_AVAIL_F_NO_INTERRUPT was ignored and interrupts were raised.
> + */
> + vp_get_isr(GET_GLOBAL(vdrive_g->ioaddr));
> +
> return status == VIRTIO_BLK_S_OK ? DISK_RET_SUCCESS : DISK_RET_EBADTRACK;
> }
>
> diff --git a/src/virtio-pci.h b/src/virtio-pci.h
> index 9da761d..d21d5a5 100644
> --- a/src/virtio-pci.h
> +++ b/src/virtio-pci.h
> @@ -71,6 +71,10 @@ static inline void vp_set_status(unsigned int ioaddr, u8
> status)
> outb(status, ioaddr + VIRTIO_PCI_STATUS);
> }
>
> +static inline u8 vp_get_isr(unsigned int ioaddr)
> +{
> + return inb(ioaddr + VIRTIO_PCI_ISR);
> +}
>
> static inline void vp_reset(unsigned int ioaddr)
> {
> --
> 1.7.1
--
Gleb.