A "word" is 16 bit. 64 bit integers like virtio uses are not dwords,
they are actually qwords. Fix up macro names accordingly.
Fixes: e7d4c1c5a546 ("virtio: introduce extended features")
Cc: "Paolo Abeni" <pabeni@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
drivers/vhost/net.c | 10 +++++-----
drivers/virtio/virtio.c | 8 ++++----
drivers/virtio/virtio_debug.c | 2 +-
include/linux/virtio.h | 2 +-
include/linux/virtio_features.h | 24 ++++++++++++------------
include/linux/virtio_pci_modern.h | 8 ++++----
scripts/lib/kdoc/kdoc_parser.py | 2 +-
7 files changed, 28 insertions(+), 28 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 35ded4330431..43d51fb1f8ea 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -69,7 +69,7 @@ MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
#define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
-static const u64 vhost_net_features[VIRTIO_FEATURES_DWORDS] = {
+static const u64 vhost_net_features[VIRTIO_FEATURES_QWORDS] = {
VHOST_FEATURES |
(1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
(1ULL << VIRTIO_NET_F_MRG_RXBUF) |
@@ -1720,7 +1720,7 @@ static long vhost_net_set_owner(struct vhost_net *n)
static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
unsigned long arg)
{
- u64 all_features[VIRTIO_FEATURES_DWORDS];
+ u64 all_features[VIRTIO_FEATURES_QWORDS];
struct vhost_net *n = f->private_data;
void __user *argp = (void __user *)arg;
u64 __user *featurep = argp;
@@ -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, VIRTIO_FEATURES_QWORDS);
if (copy_to_user(argp, vhost_net_features,
copied * sizeof(u64)))
return -EFAULT;
@@ -1767,7 +1767,7 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
virtio_features_zero(all_features);
argp += sizeof(u64);
- copied = min(count, VIRTIO_FEATURES_DWORDS);
+ copied = min(count, VIRTIO_FEATURES_QWORDS);
if (copy_from_user(all_features, argp, copied * sizeof(u64)))
return -EFAULT;
@@ -1783,7 +1783,7 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
return -EOPNOTSUPP;
}
- for (i = 0; i < VIRTIO_FEATURES_DWORDS; i++)
+ for (i = 0; i < VIRTIO_FEATURES_QWORDS; i++)
if (all_features[i] & ~vhost_net_features[i])
return -EOPNOTSUPP;
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index a09eb4d62f82..08f8357cdd39 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -272,8 +272,8 @@ static int virtio_dev_probe(struct device *_d)
int err, i;
struct virtio_device *dev = dev_to_virtio(_d);
struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
- u64 device_features[VIRTIO_FEATURES_DWORDS];
- u64 driver_features[VIRTIO_FEATURES_DWORDS];
+ u64 device_features[VIRTIO_FEATURES_QWORDS];
+ u64 driver_features[VIRTIO_FEATURES_QWORDS];
u64 driver_features_legacy;
/* We have a driver! */
@@ -303,7 +303,7 @@ static int virtio_dev_probe(struct device *_d)
}
if (virtio_features_test_bit(device_features, VIRTIO_F_VERSION_1)) {
- for (i = 0; i < VIRTIO_FEATURES_DWORDS; ++i)
+ for (i = 0; i < VIRTIO_FEATURES_QWORDS; ++i)
dev->features_array[i] = driver_features[i] &
device_features[i];
} else {
@@ -325,7 +325,7 @@ static int virtio_dev_probe(struct device *_d)
goto err;
if (drv->validate) {
- u64 features[VIRTIO_FEATURES_DWORDS];
+ u64 features[VIRTIO_FEATURES_QWORDS];
virtio_features_copy(features, dev->features_array);
err = drv->validate(dev);
diff --git a/drivers/virtio/virtio_debug.c b/drivers/virtio/virtio_debug.c
index d58713ddf2e5..40f6b815caef 100644
--- a/drivers/virtio/virtio_debug.c
+++ b/drivers/virtio/virtio_debug.c
@@ -8,7 +8,7 @@ static struct dentry *virtio_debugfs_dir;
static int virtio_debug_device_features_show(struct seq_file *s, void *data)
{
- u64 device_features[VIRTIO_FEATURES_DWORDS];
+ u64 device_features[VIRTIO_FEATURES_QWORDS];
struct virtio_device *dev = s->private;
unsigned int i;
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 96c66126c074..5b258451dc0e 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -177,7 +177,7 @@ struct virtio_device {
union virtio_map vmap;
#ifdef CONFIG_VIRTIO_DEBUG
struct dentry *debugfs_dir;
- u64 debugfs_filter_features[VIRTIO_FEATURES_DWORDS];
+ u64 debugfs_filter_features[VIRTIO_FEATURES_QWORDS];
#endif
};
diff --git a/include/linux/virtio_features.h b/include/linux/virtio_features.h
index f748f2f87de8..bf41d8ec50ef 100644
--- a/include/linux/virtio_features.h
+++ b/include/linux/virtio_features.h
@@ -4,15 +4,15 @@
#include <linux/bits.h>
-#define VIRTIO_FEATURES_DWORDS 2
-#define VIRTIO_FEATURES_MAX (VIRTIO_FEATURES_DWORDS * 64)
-#define VIRTIO_FEATURES_WORDS (VIRTIO_FEATURES_DWORDS * 2)
+#define VIRTIO_FEATURES_QWORDS 2
+#define VIRTIO_FEATURES_MAX (VIRTIO_FEATURES_QWORDS * 64)
+#define VIRTIO_FEATURES_WORDS (VIRTIO_FEATURES_QWORDS * 2)
#define VIRTIO_BIT(b) BIT_ULL((b) & 0x3f)
-#define VIRTIO_DWORD(b) ((b) >> 6)
+#define VIRTIO_QWORD(b) ((b) >> 6)
#define VIRTIO_DECLARE_FEATURES(name) \
union { \
u64 name; \
- u64 name##_array[VIRTIO_FEATURES_DWORDS];\
+ u64 name##_array[VIRTIO_FEATURES_QWORDS];\
}
static inline bool virtio_features_chk_bit(unsigned int bit)
@@ -34,26 +34,26 @@ static inline bool virtio_features_test_bit(const u64 *features,
unsigned int bit)
{
return virtio_features_chk_bit(bit) &&
- !!(features[VIRTIO_DWORD(bit)] & VIRTIO_BIT(bit));
+ !!(features[VIRTIO_QWORD(bit)] & VIRTIO_BIT(bit));
}
static inline void virtio_features_set_bit(u64 *features,
unsigned int bit)
{
if (virtio_features_chk_bit(bit))
- features[VIRTIO_DWORD(bit)] |= VIRTIO_BIT(bit);
+ features[VIRTIO_QWORD(bit)] |= VIRTIO_BIT(bit);
}
static inline void virtio_features_clear_bit(u64 *features,
unsigned int bit)
{
if (virtio_features_chk_bit(bit))
- features[VIRTIO_DWORD(bit)] &= ~VIRTIO_BIT(bit);
+ features[VIRTIO_QWORD(bit)] &= ~VIRTIO_BIT(bit);
}
static inline void virtio_features_zero(u64 *features)
{
- memset(features, 0, sizeof(features[0]) * VIRTIO_FEATURES_DWORDS);
+ memset(features, 0, sizeof(features[0]) * VIRTIO_FEATURES_QWORDS);
}
static inline void virtio_features_from_u64(u64 *features, u64 from)
@@ -66,7 +66,7 @@ static inline bool virtio_features_equal(const u64 *f1, const u64 *f2)
{
int i;
- for (i = 0; i < VIRTIO_FEATURES_DWORDS; ++i)
+ for (i = 0; i < VIRTIO_FEATURES_QWORDS; ++i)
if (f1[i] != f2[i])
return false;
return true;
@@ -74,14 +74,14 @@ static inline bool virtio_features_equal(const u64 *f1, const u64 *f2)
static inline void virtio_features_copy(u64 *to, const u64 *from)
{
- memcpy(to, from, sizeof(to[0]) * VIRTIO_FEATURES_DWORDS);
+ memcpy(to, from, sizeof(to[0]) * VIRTIO_FEATURES_QWORDS);
}
static inline void virtio_features_andnot(u64 *to, const u64 *f1, const u64 *f2)
{
int i;
- for (i = 0; i < VIRTIO_FEATURES_DWORDS; i++)
+ for (i = 0; i < VIRTIO_FEATURES_QWORDS; i++)
to[i] = f1[i] & ~f2[i];
}
diff --git a/include/linux/virtio_pci_modern.h b/include/linux/virtio_pci_modern.h
index 48bc12d1045b..15818bd04716 100644
--- a/include/linux/virtio_pci_modern.h
+++ b/include/linux/virtio_pci_modern.h
@@ -107,7 +107,7 @@ void vp_modern_set_extended_features(struct virtio_pci_modern_device *mdev,
static inline u64
vp_modern_get_features(struct virtio_pci_modern_device *mdev)
{
- u64 features_array[VIRTIO_FEATURES_DWORDS];
+ u64 features_array[VIRTIO_FEATURES_QWORDS];
vp_modern_get_extended_features(mdev, features_array);
return features_array[0];
@@ -116,11 +116,11 @@ vp_modern_get_features(struct virtio_pci_modern_device *mdev)
static inline u64
vp_modern_get_driver_features(struct virtio_pci_modern_device *mdev)
{
- u64 features_array[VIRTIO_FEATURES_DWORDS];
+ u64 features_array[VIRTIO_FEATURES_QWORDS];
int i;
vp_modern_get_driver_extended_features(mdev, features_array);
- for (i = 1; i < VIRTIO_FEATURES_DWORDS; ++i)
+ for (i = 1; i < VIRTIO_FEATURES_QWORDS; ++i)
WARN_ON_ONCE(features_array[i]);
return features_array[0];
}
@@ -128,7 +128,7 @@ vp_modern_get_driver_features(struct virtio_pci_modern_device *mdev)
static inline void
vp_modern_set_features(struct virtio_pci_modern_device *mdev, u64 features)
{
- u64 features_array[VIRTIO_FEATURES_DWORDS];
+ u64 features_array[VIRTIO_FEATURES_QWORDS];
virtio_features_from_u64(features_array, features);
vp_modern_set_extended_features(mdev, features_array);
diff --git a/scripts/lib/kdoc/kdoc_parser.py b/scripts/lib/kdoc/kdoc_parser.py
index fe730099eca8..5d629aebc8f0 100644
--- a/scripts/lib/kdoc/kdoc_parser.py
+++ b/scripts/lib/kdoc/kdoc_parser.py
@@ -638,7 +638,7 @@ class KernelDoc:
(KernRe(r'(?:__)?DECLARE_FLEX_ARRAY\s*\(' + args_pattern + r',\s*' + args_pattern + r'\)', re.S), r'\1 \2[]'),
(KernRe(r'DEFINE_DMA_UNMAP_ADDR\s*\(' + args_pattern + r'\)', re.S), r'dma_addr_t \1'),
(KernRe(r'DEFINE_DMA_UNMAP_LEN\s*\(' + args_pattern + r'\)', re.S), r'__u32 \1'),
- (KernRe(r'VIRTIO_DECLARE_FEATURES\s*\(' + args_pattern + r'\)', re.S), r'u64 \1; u64 \1_array[VIRTIO_FEATURES_DWORDS]'),
+ (KernRe(r'VIRTIO_DECLARE_FEATURES\s*\(' + args_pattern + r'\)', re.S), r'u64 \1; u64 \1_array[VIRTIO_FEATURES_QWORDS]'),
]
# Regexes here are guaranteed to have the end limiter matching
--
MSTOn Thu, Oct 09, 2025 at 07:24:08AM -0400, Michael S. Tsirkin wrote:
> A "word" is 16 bit. 64 bit integers like virtio uses are not dwords,
> they are actually qwords.
I'm having trouble with this....
This bit makes sense. 4x 16bits = 64 bits.
> -static const u64 vhost_net_features[VIRTIO_FEATURES_DWORDS] = {
> +static const u64 vhost_net_features[VIRTIO_FEATURES_QWORDS] = {
If this was u16, and VIRTIO_FEATURES_QWORDS was 4, which the Q would
imply, than i would agree with what you are saying. But this is a u64
type. It is already a QWORD, and this is an array of two of them.
I think the real issue here is not D vs Q, but WORD. We have a default
meaning of a u16 for a word, especially in C. But that is not the
actual definition of a word a computer scientist would use. Wikipedia
has:
In computing, a word is any processor design's natural unit of
data. A word is a fixed-sized datum handled as a unit by the
instruction set or the hardware of the processor.
A word can be any size. In this context, virtio is not referring to
the instruction set, but a protocol. Are all fields in this protocol
u64? Hence word is u64? And this is an array of two words? That would
make DWORD correct, it is two words.
If you want to change anything here, i would actually change WORD to
something else, maybe FIELD?
And i could be wrong here, i've not looked at the actual protocol, so
i've no idea if all fields in the protocol are u64. There are
protocols like this, IPv6 uses u32, not octets, and the length field
in the headers refer to the number of u32s in the header.
Andrew
On Thu, Oct 09, 2025 at 02:31:04PM +0200, Andrew Lunn wrote:
> On Thu, Oct 09, 2025 at 07:24:08AM -0400, Michael S. Tsirkin wrote:
> > A "word" is 16 bit. 64 bit integers like virtio uses are not dwords,
> > they are actually qwords.
>
> I'm having trouble with this....
>
> This bit makes sense. 4x 16bits = 64 bits.
>
> > -static const u64 vhost_net_features[VIRTIO_FEATURES_DWORDS] = {
> > +static const u64 vhost_net_features[VIRTIO_FEATURES_QWORDS] = {
>
> If this was u16, and VIRTIO_FEATURES_QWORDS was 4, which the Q would
> imply, than i would agree with what you are saying. But this is a u64
> type. It is already a QWORD, and this is an array of two of them.
I don't get what you are saying here.
It's an array of qwords and VIRTIO_FEATURES_QWORDS tells you
how many QWORDS are needed to fit all of them.
This is how C arrays are declared.
> I think the real issue here is not D vs Q, but WORD. We have a default
> meaning of a u16 for a word, especially in C. But that is not the
> actual definition of a word a computer scientist would use. Wikipedia
> has:
>
> In computing, a word is any processor design's natural unit of
> data. A word is a fixed-sized datum handled as a unit by the
> instruction set or the hardware of the processor.
>
> A word can be any size. In this context, virtio is not referring to
> the instruction set, but a protocol. Are all fields in this protocol
> u64? Hence word is u64? And this is an array of two words? That would
> make DWORD correct, it is two words.
>
> If you want to change anything here, i would actually change WORD to
> something else, maybe FIELD?
>
> And i could be wrong here, i've not looked at the actual protocol, so
> i've no idea if all fields in the protocol are u64. There are
> protocols like this, IPv6 uses u32, not octets, and the length field
> in the headers refer to the number of u32s in the header.
>
> Andrew
Virtio uses "dword" to mean "32 bits" in several places:
device-types/i2c/description.tex:The \field{padding} is used to pad to full dword.
pads to 32 bit
transport-pci.tex: u8 padding[2]; /* Pad to full dword. */
same
Under pci, the meaning is also generally as I use it here.
E.g.:
Documentation/PCI/pci.rst:You can use `pci_(read|write)_config_(byte|word|dword)` to access the config
--
MST
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