From 4e0daae583aeaac8e2a7fb25d02533bf40ecf29b Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Wed, 7 Jul 2010 13:34:22 +0100 Subject: [PATCH] virtio: Clear interrupt status register in virtio-blk 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 --- src/virtio-blk.c | 6 ++++++ src/virtio-pci.h | 4 ++++ 2 files changed, 10 insertions(+) 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) { -- 2.25.1