[SRU][J:linux-gcp/J:linux-gke][PATCH v3 09/13] idpf: enable WB_ON_ITR
Ian Whitfield
ian.whitfield at canonical.com
Tue Apr 1 16:22:08 UTC 2025
From: Joshua Hay <joshua.a.hay at intel.com>
BugLink: https://bugs.launchpad.net/bugs/2093622
Tell hardware to write back completed descriptors even when interrupts
are disabled. Otherwise, descriptors might not be written back until
the hardware can flush a full cacheline of descriptors. This can cause
unnecessary delays when traffic is light (or even trigger Tx queue
timeout).
The example scenario to reproduce the Tx timeout if the fix is not
applied:
- configure at least 2 Tx queues to be assigned to the same q_vector,
- generate a huge Tx traffic on the first Tx queue
- try to send a few packets using the second Tx queue.
In such a case Tx timeout will appear on the second Tx queue because no
completion descriptors are written back for that queue while interrupts
are disabled due to NAPI polling.
Fixes: c2d548cad150 ("idpf: add TX splitq napi poll support")
Fixes: a5ab9ee0df0b ("idpf: add singleq start_xmit and napi poll")
Signed-off-by: Joshua Hay <joshua.a.hay at intel.com>
Co-developed-by: Michal Kubiak <michal.kubiak at intel.com>
Signed-off-by: Michal Kubiak <michal.kubiak at intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel at intel.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin at intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen at intel.com>
(backported from commit 9c4a27da0ecc4080dfcd63903dd94f01ba1399dd)
[ijwhitfield: Missing commit
5a816aae2d46 ("idpf: strictly assert cachelines of queue and queue vector structures")
optimizes cacheline usage of structs in idpf, but depends on a libeth
change outside of idpf, so was excluded. Patch was adjusted to account
for the difference in struct member ordering.
Context was adjusted due to missing unrelated commit
74d1412ac8f3 ("idpf: use libeth Rx buffer management for payload buffer")]
Signed-off-by: Ian Whitfield <ian.whitfield at canonical.com>
---
drivers/net/ethernet/intel/idpf/idpf_dev.c | 2 ++
.../ethernet/intel/idpf/idpf_singleq_txrx.c | 6 ++++-
drivers/net/ethernet/intel/idpf/idpf_txrx.c | 7 +++++-
drivers/net/ethernet/intel/idpf/idpf_txrx.h | 25 +++++++++++++++++++
drivers/net/ethernet/intel/idpf/idpf_vf_dev.c | 2 ++
5 files changed, 40 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/intel/idpf/idpf_dev.c b/drivers/net/ethernet/intel/idpf/idpf_dev.c
index 34ad1ac46b78..2c6776086130 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_dev.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_dev.c
@@ -96,8 +96,10 @@ static int idpf_intr_reg_init(struct idpf_vport *vport)
intr->dyn_ctl = idpf_get_reg_addr(adapter,
reg_vals[vec_id].dyn_ctl_reg);
intr->dyn_ctl_intena_m = PF_GLINT_DYN_CTL_INTENA_M;
+ intr->dyn_ctl_intena_msk_m = PF_GLINT_DYN_CTL_INTENA_MSK_M;
intr->dyn_ctl_itridx_s = PF_GLINT_DYN_CTL_ITR_INDX_S;
intr->dyn_ctl_intrvl_s = PF_GLINT_DYN_CTL_INTERVAL_S;
+ intr->dyn_ctl_wb_on_itr_m = PF_GLINT_DYN_CTL_WB_ON_ITR_M;
spacing = IDPF_ITR_IDX_SPACING(reg_vals[vec_id].itrn_index_spacing,
IDPF_PF_ITR_IDX_SPACING);
diff --git a/drivers/net/ethernet/intel/idpf/idpf_singleq_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_singleq_txrx.c
index 636a327b3dd2..2d6514cbae43 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_singleq_txrx.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_singleq_txrx.c
@@ -1182,8 +1182,10 @@ int idpf_vport_singleq_napi_poll(struct napi_struct *napi, int budget)
&work_done);
/* If work not completed, return budget and polling will return */
- if (!clean_complete)
+ if (!clean_complete) {
+ idpf_vport_intr_set_wb_on_itr(q_vector);
return budget;
+ }
work_done = min_t(int, work_done, budget - 1);
@@ -1192,6 +1194,8 @@ int idpf_vport_singleq_napi_poll(struct napi_struct *napi, int budget)
*/
if (likely(napi_complete_done(napi, work_done)))
idpf_vport_intr_update_itr_ena_irq(q_vector);
+ else
+ idpf_vport_intr_set_wb_on_itr(q_vector);
return work_done;
}
diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
index 2126ccd68968..69befe8a60a4 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
@@ -3822,6 +3822,7 @@ void idpf_vport_intr_update_itr_ena_irq(struct idpf_q_vector *q_vector)
/* net_dim() updates ITR out-of-band using a work item */
idpf_net_dim(q_vector);
+ q_vector->wb_on_itr = false;
intval = idpf_vport_intr_buildreg_itr(q_vector,
IDPF_NO_ITR_UPDATE_IDX, 0);
@@ -4118,8 +4119,10 @@ static int idpf_vport_splitq_napi_poll(struct napi_struct *napi, int budget)
clean_complete &= idpf_tx_splitq_clean_all(q_vector, budget, &work_done);
/* If work not completed, return budget and polling will return */
- if (!clean_complete)
+ if (!clean_complete) {
+ idpf_vport_intr_set_wb_on_itr(q_vector);
return budget;
+ }
work_done = min_t(int, work_done, budget - 1);
@@ -4128,6 +4131,8 @@ static int idpf_vport_splitq_napi_poll(struct napi_struct *napi, int budget)
*/
if (likely(napi_complete_done(napi, work_done)))
idpf_vport_intr_update_itr_ena_irq(q_vector);
+ else
+ idpf_vport_intr_set_wb_on_itr(q_vector);
/* Switch to poll mode in the tear-down path after sending disable
* queues virtchnl message, as the interrupts will be disabled after
diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.h b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
index 8442dcf8f870..2e8c7808b725 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.h
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.h
@@ -481,9 +481,11 @@ struct idpf_vec_regs {
* struct idpf_intr_reg
* @dyn_ctl: Dynamic control interrupt register
* @dyn_ctl_intena_m: Mask for dyn_ctl interrupt enable
+ * @dyn_ctl_intena_msk_m: Mask for dyn_ctl interrupt enable mask
* @dyn_ctl_itridx_s: Register bit offset for ITR index
* @dyn_ctl_itridx_m: Mask for ITR index
* @dyn_ctl_intrvl_s: Register bit offset for ITR interval
+ * @dyn_ctl_wb_on_itr_m: Mask for WB on ITR feature
* @rx_itr: RX ITR register
* @tx_itr: TX ITR register
* @icr_ena: Interrupt cause register offset
@@ -492,9 +494,11 @@ struct idpf_vec_regs {
struct idpf_intr_reg {
void __iomem *dyn_ctl;
u32 dyn_ctl_intena_m;
+ u32 dyn_ctl_intena_msk_m;
u32 dyn_ctl_itridx_s;
u32 dyn_ctl_itridx_m;
u32 dyn_ctl_intrvl_s;
+ u32 dyn_ctl_wb_on_itr_m;
void __iomem *rx_itr;
void __iomem *tx_itr;
void __iomem *icr_ena;
@@ -525,6 +529,7 @@ struct idpf_intr_reg {
* @num_bufq: Number of buffer queues
* @bufq: Array of buffer queues to service
* @total_events: Number of interrupts processed
+ * @wb_on_itr: whether WB on ITR is enabled
* @name: Queue vector name
*/
struct idpf_q_vector {
@@ -555,6 +560,7 @@ struct idpf_q_vector {
struct idpf_buf_queue **bufq;
u16 total_events;
+ bool wb_on_itr;
char *name;
};
@@ -1113,6 +1119,25 @@ static inline void idpf_rx_sync_for_cpu(struct idpf_rx_buf *rx_buf, u32 len)
page_pool_get_dma_dir(pp));
}
+/**
+ * idpf_vport_intr_set_wb_on_itr - enable descriptor writeback on disabled interrupts
+ * @q_vector: pointer to queue vector struct
+ */
+static inline void idpf_vport_intr_set_wb_on_itr(struct idpf_q_vector *q_vector)
+{
+ struct idpf_intr_reg *reg;
+
+ if (q_vector->wb_on_itr)
+ return;
+
+ q_vector->wb_on_itr = true;
+ reg = &q_vector->intr_reg;
+
+ writel(reg->dyn_ctl_wb_on_itr_m | reg->dyn_ctl_intena_msk_m |
+ (IDPF_NO_ITR_UPDATE_IDX << reg->dyn_ctl_itridx_s),
+ reg->dyn_ctl);
+}
+
int idpf_vport_singleq_napi_poll(struct napi_struct *napi, int budget);
void idpf_vport_init_num_qs(struct idpf_vport *vport,
struct virtchnl2_create_vport *vport_msg);
diff --git a/drivers/net/ethernet/intel/idpf/idpf_vf_dev.c b/drivers/net/ethernet/intel/idpf/idpf_vf_dev.c
index 8ade4e3a9fe1..f5b0a0666636 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_vf_dev.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_vf_dev.c
@@ -96,7 +96,9 @@ static int idpf_vf_intr_reg_init(struct idpf_vport *vport)
intr->dyn_ctl = idpf_get_reg_addr(adapter,
reg_vals[vec_id].dyn_ctl_reg);
intr->dyn_ctl_intena_m = VF_INT_DYN_CTLN_INTENA_M;
+ intr->dyn_ctl_intena_msk_m = VF_INT_DYN_CTLN_INTENA_MSK_M;
intr->dyn_ctl_itridx_s = VF_INT_DYN_CTLN_ITR_INDX_S;
+ intr->dyn_ctl_wb_on_itr_m = VF_INT_DYN_CTLN_WB_ON_ITR_M;
spacing = IDPF_ITR_IDX_SPACING(reg_vals[vec_id].itrn_index_spacing,
IDPF_VF_ITR_IDX_SPACING);
--
2.43.0
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