[PATCHv2 12/14] virtio: 64 bit features

Michael S. Tsirkin
2011-05-19T23:12:28Z

Extend features to 64 bit so we can use more
transport bits.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
drivers/lguest/lguest_device.c | 8 ++++----
drivers/s390/kvm/kvm_virtio.c | 8 ++++----
drivers/virtio/virtio.c | 8 ++++----
drivers/virtio/virtio_pci.c | 34 ++++++++++++++++++++++++++++------
drivers/virtio/virtio_ring.c | 2 ++
include/linux/virtio.h | 2 +-
include/linux/virtio_config.h | 15 +++++++++------
include/linux/virtio_pci.h | 9 ++++++++-
8 files changed, 60 insertions(+), 26 deletions(-)

diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 69c84a1..d2d6953 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -93,17 +93,17 @@ static unsigned desc_size(const struct lguest_device_desc *desc)
}

/* This gets the device's feature bits. */
-static u32 lg_get_features(struct virtio_device *vdev)
+static u64 lg_get_features(struct virtio_device *vdev)
{
unsigned int i;
- u32 features = 0;
+ u64 features = 0;
struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
u8 *in_features = lg_features(desc);

/* We do this the slow but generic way. */
- for (i = 0; i < min(desc->feature_len * 8, 32); i++)
+ for (i = 0; i < min(desc->feature_len * 8, 64); i++)
if (in_features[i / 8] & (1 << (i % 8)))
- features |= (1 << i);
+ features |= (1ull << i);

return features;
}
diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index 414427d..c56293c 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -79,16 +79,16 @@ static unsigned desc_size(const struct kvm_device_desc *desc)
}

/* This gets the device's feature bits. */
-static u32 kvm_get_features(struct virtio_device *vdev)
+static u64 kvm_get_features(struct virtio_device *vdev)
{
unsigned int i;
- u32 features = 0;
+ u64 features = 0;
struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
u8 *in_features = kvm_vq_features(desc);

- for (i = 0; i < min(desc->feature_len * 8, 32); i++)
+ for (i = 0; i < min(desc->feature_len * 8, 64); i++)
if (in_features[i / 8] & (1 << (i % 8)))
- features |= (1 << i);
+ features |= (1ull << i);
return features;
}

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index efb35aa..52b24d7 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -112,7 +112,7 @@ static int virtio_dev_probe(struct device *_d)
struct virtio_device *dev = container_of(_d,struct virtio_device,dev);
struct virtio_driver *drv = container_of(dev->dev.driver,
struct virtio_driver, driver);
- u32 device_features;
+ u64 device_features;

/* We have a driver! */
add_status(dev, VIRTIO_CONFIG_S_DRIVER);
@@ -124,14 +124,14 @@ static int virtio_dev_probe(struct device *_d)
memset(dev->features, 0, sizeof(dev->features));
for (i = 0; i < drv->feature_table_size; i++) {
unsigned int f = drv->feature_table[i];
- BUG_ON(f >= 32);
- if (device_features & (1 << f))
+ BUG_ON(f >= 64);
+ if (device_features & (1ull << f))
set_bit(f, dev->features);
}

/* Transport features always preserved to pass to finalize_features. */
for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
- if (device_features & (1 << i))
+ if (device_features & (1ull << i))
set_bit(i, dev->features);

dev->config->finalize_features(dev);
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index 4fb5b2b..04b216f 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -44,6 +44,8 @@ struct virtio_pci_device
spinlock_t lock;
struct list_head virtqueues;

+ /* 64 bit features */
+ int features_hi;
/* MSI-X support */
int msix_enabled;
int intx_enabled;
@@ -103,26 +105,46 @@ static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev)
}

/* virtio config->get_features() implementation */
-static u32 vp_get_features(struct virtio_device *vdev)
+static u64 vp_get_features(struct virtio_device *vdev)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+ u32 flo, fhi;

- /* When someone needs more than 32 feature bits, we'll need to
+ /* When someone needs more than 32 feature bits, we need to
* steal a bit to indicate that the rest are somewhere else. */
- return ioread32(vp_dev->ioaddr + VIRTIO_PCI_HOST_FEATURES);
+ flo = ioread32(vp_dev->ioaddr + VIRTIO_PCI_HOST_FEATURES);
+ if (flo & (0x1 << VIRTIO_F_FEATURES_HI)) {
+ vp_dev->features_hi = 1;
+ iowrite32(0x1 << VIRTIO_F_FEATURES_HI,
+ vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);
+ fhi = ioread32(vp_dev->ioaddr + VIRTIO_PCI_HOST_FEATURES_HI);
+ } else {
+ vp_dev->features_hi = 0;
+ fhi = 0;
+ }
+ return (((u64)fhi) << 32) | flo;
}

/* virtio config->finalize_features() implementation */
static void vp_finalize_features(struct virtio_device *vdev)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+ u32 flo, fhi;

/* Give virtio_ring a chance to accept features. */
vring_transport_features(vdev);

- /* We only support 32 feature bits. */
- BUILD_BUG_ON(ARRAY_SIZE(vdev->features) != 1);
- iowrite32(vdev->features[0], vp_dev->ioaddr+VIRTIO_PCI_GUEST_FEATURES);
+ /* We only support 64 feature bits. */
+ BUILD_BUG_ON(ARRAY_SIZE(vdev->features) != 64 / BITS_PER_LONG);
+ flo = vdev->features[0];
+ fhi = vdev->features[64 / BITS_PER_LONG - 1] >> (BITS_PER_LONG - 32);
+ iowrite32(flo, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);
+ if (flo & (0x1 << VIRTIO_F_FEATURES_HI)) {
+ vp_dev->features_hi = 1;
+ iowrite32(fhi, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES_HI);
+ } else {
+ vp_dev->features_hi = 0;
+ }
}

/* virtio config->get() implementation */
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 8218fe6..4a7a651 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -534,6 +534,8 @@ void vring_transport_features(struct virtio_device *vdev)

for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) {
switch (i) {
+ case VIRTIO_F_FEATURES_HI:
+ break;
case VIRTIO_RING_F_INDIRECT_DESC:
break;
case VIRTIO_RING_F_EVENT_IDX:
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 58c0953..944ebcd 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -119,7 +119,7 @@ struct virtio_device {
struct virtio_config_ops *config;
struct list_head vqs;
/* Note that this is a Linux set_bit-style bitmap. */
- unsigned long features[1];
+ unsigned long features[64 / BITS_PER_LONG];
void *priv;
};

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 800617b..b1a1981 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -18,16 +18,19 @@
/* We've given up on this device. */
#define VIRTIO_CONFIG_S_FAILED 0x80

-/* Some virtio feature bits (currently bits 28 through 31) are reserved for the
+/* Some virtio feature bits (currently bits 28 through 39) are reserved for the
* transport being used (eg. virtio_ring), the rest are per-device feature
* bits. */
#define VIRTIO_TRANSPORT_F_START 28
-#define VIRTIO_TRANSPORT_F_END 32
+#define VIRTIO_TRANSPORT_F_END 40

/* Do we get callbacks when the ring is completely used, even if we've
* suppressed them? */
#define VIRTIO_F_NOTIFY_ON_EMPTY 24

+/* Enables feature bits 32 to 63 (only really required for virtio_pci). */
+#define VIRTIO_F_FEATURES_HI 31
+
#ifdef __KERNEL__
#include <linux/err.h>
#include <linux/virtio.h>
@@ -72,7 +75,7 @@
* @del_vqs: free virtqueues found by find_vqs().
* @get_features: get the array of feature bits for this device.
* vdev: the virtio_device
- * Returns the first 32 feature bits (all we currently need).
+ * Returns the first 64 feature bits (all we currently need).
* @finalize_features: confirm what device features we'll be using.
* vdev: the virtio_device
* This gives the final feature bits for the device: it can change
@@ -92,7 +95,7 @@ struct virtio_config_ops {
vq_callback_t *callbacks[],
const char *names[]);
void (*del_vqs)(struct virtio_device *);
- u32 (*get_features)(struct virtio_device *vdev);
+ u64 (*get_features)(struct virtio_device *vdev);
void (*finalize_features)(struct virtio_device *vdev);
};

@@ -110,9 +113,9 @@ static inline bool virtio_has_feature(const struct virtio_device *vdev,
{
/* Did you forget to fix assumptions on max features? */
if (__builtin_constant_p(fbit))
- BUILD_BUG_ON(fbit >= 32);
+ BUILD_BUG_ON(fbit >= 64);
else
- BUG_ON(fbit >= 32);
+ BUG_ON(fbit >= 64);

if (fbit < VIRTIO_TRANSPORT_F_START)
virtio_check_driver_offered_feature(vdev, fbit);
diff --git a/include/linux/virtio_pci.h b/include/linux/virtio_pci.h
index 9a3d7c4..90f9725 100644
--- a/include/linux/virtio_pci.h
+++ b/include/linux/virtio_pci.h
@@ -55,9 +55,16 @@
/* Vector value used to disable MSI for queue */
#define VIRTIO_MSI_NO_VECTOR 0xffff

+/* An extended 32-bit r/o bitmask of the features supported by the host */
+#define VIRTIO_PCI_HOST_FEATURES_HI 24
+
+/* An extended 32-bit r/w bitmask of features activated by the guest */
+#define VIRTIO_PCI_GUEST_FEATURES_HI 28
+
/* The remaining space is defined by each driver as the per-driver
* configuration space */
-#define VIRTIO_PCI_CONFIG(dev) ((dev)->msix_enabled ? 24 : 20)
+#define VIRTIO_PCI_CONFIG(dev) ((dev)->features_hi ? 32 : \
+ (dev)->msix_enabled ? 24 : 20)

/* Virtio ABI version, this must match exactly */
#define VIRTIO_PCI_ABI_VERSION 0
--
1.7.5.53.gc233e