From: Yufeng Wang <[email protected]>
Define VIRTIO_F_SQCQ_POLL (bit 42) and the associated SQ/CQ doorbell
structures for split virtqueue polling mode.
- include/uapi/linux/virtio_config.h: feature bit 42
- include/uapi/linux/virtio_ring.h: struct vring_sq, struct vring_cq
(128-byte aligned for cache-line isolation on ARM Neoverse N2/V2)
- include/uapi/linux/virtio_pci.h: sqe/cqe_ring PCI config registers
at offsets 64-76
Signed-off-by: Yufeng Wang <[email protected]>
---
include/uapi/linux/virtio_config.h | 8 +++++++-
include/uapi/linux/virtio_pci.h | 9 +++++++++
include/uapi/linux/virtio_ring.h | 25 +++++++++++++++++++++++++
3 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/virtio_config.h
b/include/uapi/linux/virtio_config.h
index 2445f365bce7..dbda23e44b62 100644
--- a/include/uapi/linux/virtio_config.h
+++ b/include/uapi/linux/virtio_config.h
@@ -52,7 +52,7 @@
* rest are per-device feature bits.
*/
#define VIRTIO_TRANSPORT_F_START 28
-#define VIRTIO_TRANSPORT_F_END 42
+#define VIRTIO_TRANSPORT_F_END 43
#ifndef VIRTIO_CONFIG_NO_LEGACY
/* Do we get callbacks when the ring is completely used, even if we've
@@ -120,4 +120,10 @@
*/
#define VIRTIO_F_ADMIN_VQ 41
+/*
+ * This feature indicates that both driver and device support
+ * SQ/CQ polling mode to replace interrupt-based notifications.
+ */
+#define VIRTIO_F_SQCQ_POLL 42
+
#endif /* _UAPI_LINUX_VIRTIO_CONFIG_H */
diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h
index e732e3456e27..f5058d1b4b16 100644
--- a/include/uapi/linux/virtio_pci.h
+++ b/include/uapi/linux/virtio_pci.h
@@ -193,6 +193,11 @@ struct virtio_pci_modern_common_cfg {
__le16 admin_queue_index; /* read-only */
__le16 admin_queue_num; /* read-only */
+
+ __le32 sqe_ring_lo; /* read-write: SQ DMA addr low */
+ __le32 sqe_ring_hi; /* read-write: SQ DMA addr high */
+ __le32 cqe_ring_lo; /* read-write: CQ DMA addr low */
+ __le32 cqe_ring_hi; /* read-write: CQ DMA addr high */
};
/* Fields in VIRTIO_PCI_CAP_PCI_CFG: */
@@ -235,6 +240,10 @@ struct virtio_pci_cfg_cap {
#define VIRTIO_PCI_COMMON_Q_RESET 58
#define VIRTIO_PCI_COMMON_ADM_Q_IDX 60
#define VIRTIO_PCI_COMMON_ADM_Q_NUM 62
+#define VIRTIO_PCI_COMMON_SQE_LO 64
+#define VIRTIO_PCI_COMMON_SQE_HI 68
+#define VIRTIO_PCI_COMMON_CQE_LO 72
+#define VIRTIO_PCI_COMMON_CQE_HI 76
#endif /* VIRTIO_PCI_NO_MODERN */
diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/virtio_ring.h
index 3c478582a3c2..d1f2b9584d7c 100644
--- a/include/uapi/linux/virtio_ring.h
+++ b/include/uapi/linux/virtio_ring.h
@@ -131,6 +131,31 @@ struct vring_used {
vring_used_elem_t ring[];
};
+/*
+ * SQ/CQ doorbell structures for polling mode (VIRTIO_F_SQCQ_POLL).
+ * These are allocated separately from the vring and their DMA addresses
+ * are communicated via PCI config space registers.
+ *
+ * Ownership:
+ * SQ: Guest writes idx, Device reads it.
+ * CQ: Device writes idx, Guest reads it.
+ *
+ * Flags (8-bit):
+ * Set to 1 before sleeping, cleared to 0 after waking up.
+ * Direct assignment — no read-modify-write.
+ */
+struct vring_sq {
+ __virtio64 idx; /* Producer position (updated by guest)
*/
+ __u8 sq_need_wakeup; /* 1 = device should be woken on next
kick */
+ __u8 reserved[55]; /* Reserved for future use */
+} __attribute__((aligned(128)));
+
+struct vring_cq {
+ __virtio64 idx; /* Producer position (updated by
device) */
+ __u8 cq_need_wakeup; /* 1 = guest should be woken on
completion */
+ __u8 reserved[55]; /* Reserved for future use */
+} __attribute__((aligned(128)));
+
/*
* The ring element addresses are passed between components with different
* alignments assumptions. Thus, we might need to decrease the
compiler-selected
--
2.34.1
