From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: [PATCH 05/18] virtio: used event index interface Date: Wed, 4 May 2011 23:51:09 +0300 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Krishna Kumar , Carsten Otte , lguest@lists.ozlabs.org, Shirley Ma , kvm@vger.kernel.org, linux-s390@vger.kernel.org, netdev@vger.kernel.org, habanero@linux.vnet.ibm.com, Heiko Carstens , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, steved@us.ibm.com, Christian Borntraeger , Tom Lendacky , Martin Schwidefsky , linux390@de.ibm.com To: linux-kernel@vger.kernel.org Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org Define a new feature bit for the guest to utilize a used_event index (like Xen) instead if a flag bit to enable/disable interrupts. Signed-off-by: Michael S. Tsirkin --- include/linux/virtio_ring.h | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index e4d144b..f5c1b75 100644 --- a/include/linux/virtio_ring.h +++ b/include/linux/virtio_ring.h @@ -29,6 +29,10 @@ /* We support indirect buffer descriptors */ #define VIRTIO_RING_F_INDIRECT_DESC 28 +/* The Guest publishes the used index for which it expects an interrupt + * at the end of the avail ring. Host should ignore the avail->flags field. */ +#define VIRTIO_RING_F_USED_EVENT_IDX 29 + /* Virtio ring descriptors: 16 bytes. These can chain together via "next". */ struct vring_desc { /* Address (guest-physical). */ @@ -83,6 +87,7 @@ struct vring { * __u16 avail_flags; * __u16 avail_idx; * __u16 available[num]; + * __u16 used_event_idx; * * // Padding to the next align boundary. * char pad[]; @@ -93,6 +98,10 @@ struct vring { * struct vring_used_elem used[num]; * }; */ +/* We publish the used event index at the end of the available ring. + * It is at the end for backwards compatibility. */ +#define vring_used_event(vr) ((vr)->avail->ring[(vr)->num]) + static inline void vring_init(struct vring *vr, unsigned int num, void *p, unsigned long align) { -- 1.7.5.53.gc233e