From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [PATCH v7 28/46] vhost: make features 64 bit Date: Sun, 30 Nov 2014 18:44:33 +0300 Message-ID: <547B3B61.3090801@cogentembedded.com> References: <1417359787-10138-1-git-send-email-mst@redhat.com> <1417359787-10138-29-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Cc: thuth@linux.vnet.ibm.com, kvm@vger.kernel.org, rusty@au1.ibm.com, netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, dahi@linux.vnet.ibm.com, pbonzini@redhat.com, David Miller To: "Michael S. Tsirkin" , linux-kernel@vger.kernel.org Return-path: In-Reply-To: <1417359787-10138-29-git-send-email-mst@redhat.com> 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 Hello. On 11/30/2014 6:11 PM, Michael S. Tsirkin wrote: > We need to use bit 32 for virtio 1.0 > Signed-off-by: Michael S. Tsirkin > Reviewed-by: Jason Wang > --- > drivers/vhost/vhost.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > index 3eda654..c624b09 100644 > --- a/drivers/vhost/vhost.h > +++ b/drivers/vhost/vhost.h > @@ -106,7 +106,7 @@ struct vhost_virtqueue { > /* Protected by virtqueue mutex. */ > struct vhost_memory *memory; > void *private_data; > - unsigned acked_features; > + u64 acked_features; > /* Log write descriptors */ > void __user *log_base; > struct vhost_log *log; > @@ -174,6 +174,6 @@ enum { > > static inline int vhost_has_feature(struct vhost_virtqueue *vq, int bit) > { > - return vq->acked_features & (1 << bit); > + return vq->acked_features & (1ULL << bit); Erm, wouldn't the high word be just dropped when returning *int*? I think you need !!(vq->acked_features & (1ULL << bit)). [...] WBR, Sergei