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Tsirkin" To: Andrew Lunn Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Paolo Abeni , Jason Wang , Eugenio =?iso-8859-1?Q?P=E9rez?= , Xuan Zhuo , Jonathan Corbet , kvm@vger.kernel.org, virtualization@lists.linux.dev, linux-doc@vger.kernel.org Subject: Re: [PATCH v2 1/2] virtio: clean up features qword/dword terms Message-ID: <20251022013753-mutt-send-email-mst@kernel.org> References: <492ef5aaa196d155d0535b5b6f4ad5b3fba70a1b.1761058528.git.mst@redhat.com> <8138fb02-f7c5-4c83-a4cb-d86412d8c048@lunn.ch> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8138fb02-f7c5-4c83-a4cb-d86412d8c048@lunn.ch> On Wed, Oct 22, 2025 at 04:20:52AM +0200, Andrew Lunn wrote: > > @@ -1752,7 +1752,7 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl, > > > > /* Copy the net features, up to the user-provided buffer size */ > > argp += sizeof(u64); > > - copied = min(count, VIRTIO_FEATURES_DWORDS); > > + copied = min(count, (u64)VIRTIO_FEATURES_ARRAY_SIZE); > > Why is the cast needed? Why was 2 O.K, but (128 >> 6) needs a cast? It's not - a leftover from one of the approaches I tried, thanks! > > -#define VIRTIO_FEATURES_DWORDS 2 > > -#define VIRTIO_FEATURES_MAX (VIRTIO_FEATURES_DWORDS * 64) > > -#define VIRTIO_FEATURES_WORDS (VIRTIO_FEATURES_DWORDS * 2) > > +#define VIRTIO_FEATURES_BITS (128) > > #define VIRTIO_BIT(b) BIT_ULL((b) & 0x3f) > > -#define VIRTIO_DWORD(b) ((b) >> 6) > > +#define VIRTIO_U64(b) ((b) >> 6) > > + > > +#define VIRTIO_FEATURES_ARRAY_SIZE VIRTIO_U64(VIRTIO_FEATURES_BITS) > > Andrew