[PATCH v3] PCI: endpoint: pci-epf-vntb: Honor MSI-X selection
From: Koichiro Den
Date: Sat Sep 19 2026 - 13:20:45 EST
ntb_hw_epf tries MSI-X first and falls back to MSI. It reports the
result in COMMAND_CONFIGURE_DOORBELL. pci-epf-vntb ignores MSIX_ENABLE,
configures only MSI, and always raises peer doorbells with PCI_IRQ_MSI.
When MSI-X is selected, the host does not program MSI, so raising it can
issue a write to an invalid address. This was observed as IOMMU faults
on the RC, with no doorbell interrupts delivered.
Configure MSI-X when supported and use the selected type for peer
doorbells. Allocate the MSI-X Table and PBA in the config BAR and
configure db_count entries. Use this EPF-owned layout even if the EPC
has fixed, hardware-owned Table/PBA regions, as pci-epf-test and
nvmet-pci-epf already do.
Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP")
Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
---
Changes in v3:
- Split out the vNTB MSI-X fix and use an EPF-owned layout. (Niklas)
Niklas and I both hit an issue with hardware-owned MSI-X on RK3588:
https://lore.kernel.org/r/mmcripxdekhktnn73ikylthajkdnincwu7p2nelcpcqzexpf22@rrmmzr6hfvzf/
v2: https://lore.kernel.org/r/20260830151948.3547577-4-den@xxxxxxxxxxxxx/
@Frank, I did not carry over your R-b tag due to the change. I'm sending
this minimal fix separately so we can fix vNTB raising MSI when the host
selected MSI-X, without waiting for the RK3588 issue to be resolved.
Please take another look, thanks.
drivers/pci/endpoint/functions/pci-epf-vntb.c | 54 +++++++++++++------
1 file changed, 38 insertions(+), 16 deletions(-)
diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
index 07ba338732d4..2f6f3da1d73f 100644
--- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
@@ -148,6 +148,7 @@ struct epf_ntb {
u16 vntb_vid;
bool linkup;
+ bool peer_msix;
/*
* True when doorbells are interrupt-driven (MSI or embedded), false
@@ -155,6 +156,7 @@ struct epf_ntb {
*/
bool msi_doorbell;
u32 spad_size;
+ u32 msix_table_offset;
enum pci_barno epf_ntb_bar[VNTB_BAR_NUM];
@@ -308,6 +310,7 @@ static void epf_ntb_cmd_handler(struct work_struct *work)
switch (command) {
case COMMAND_CONFIGURE_DOORBELL:
+ ntb->peer_msix = argument & MSIX_ENABLE;
ctrl->command_status = COMMAND_STATUS_OK;
break;
case COMMAND_TEARDOWN_DOORBELL:
@@ -451,8 +454,9 @@ static void epf_ntb_config_spad_bar_free(struct epf_ntb *ntb)
* @ntb: NTB device that facilitates communication between HOST and VHOST
*
* Allocate the Local Memory mentioned in the above diagram. The size of
- * CONFIG REGION is sizeof(struct epf_ntb_ctrl) and size of SCRATCHPAD REGION
- * is obtained from "spad-count" configfs entry.
+ * CONFIG REGION is sizeof(struct epf_ntb_ctrl), plus space for the MSI-X
+ * Table and PBA if supported. The size of SCRATCHPAD REGION is obtained
+ * from "spad-count" configfs entry.
*
* Returns: Zero for success, or an error code in case of failure
*/
@@ -473,6 +477,12 @@ static int epf_ntb_config_spad_bar_alloc(struct epf_ntb *ntb)
spad_count = ntb->spad_count;
ctrl_size = ALIGN(sizeof(struct epf_ntb_ctrl), sizeof(u32));
+ if (epc_features->msix_capable) {
+ ntb->msix_table_offset = ALIGN(ctrl_size, 8);
+ ctrl_size = ntb->msix_table_offset +
+ ntb->db_count * PCI_MSIX_ENTRY_SIZE +
+ BITS_TO_U64(ntb->db_count) * sizeof(u64);
+ }
spad_size = 2 * spad_count * sizeof(u32);
base = pci_epf_alloc_space(epf, ctrl_size + spad_size,
@@ -513,12 +523,14 @@ static int epf_ntb_config_spad_bar_alloc(struct epf_ntb *ntb)
static int epf_ntb_configure_interrupt(struct epf_ntb *ntb)
{
const struct pci_epc_features *epc_features;
+ struct pci_epf *epf = ntb->epf;
struct device *dev;
int ret;
- dev = &ntb->epf->dev;
+ dev = &epf->dev;
- epc_features = pci_epc_get_features(ntb->epf->epc, ntb->epf->func_no, ntb->epf->vfunc_no);
+ epc_features = pci_epc_get_features(epf->epc, epf->func_no,
+ epf->vfunc_no);
if (!(epc_features->msix_capable || epc_features->msi_capable)) {
dev_err(dev, "MSI or MSI-X is required for doorbell\n");
@@ -532,16 +544,24 @@ static int epf_ntb_configure_interrupt(struct epf_ntb *ntb)
}
if (epc_features->msi_capable) {
- ret = pci_epc_set_msi(ntb->epf->epc,
- ntb->epf->func_no,
- ntb->epf->vfunc_no,
- 16);
+ ret = pci_epc_set_msi(epf->epc, epf->func_no, epf->vfunc_no, 16);
if (ret) {
dev_err(dev, "MSI configuration failed\n");
return ret;
}
}
+ if (epc_features->msix_capable) {
+ ret = pci_epc_set_msix(epf->epc, epf->func_no, epf->vfunc_no,
+ ntb->db_count,
+ ntb->epf_ntb_bar[BAR_CONFIG],
+ ntb->msix_table_offset);
+ if (ret) {
+ dev_err(dev, "MSI-X configuration failed\n");
+ return ret;
+ }
+ }
+
return 0;
}
@@ -1529,6 +1549,7 @@ static void vntb_epf_peer_db_work(struct work_struct *work)
struct epf_ntb *ntb = container_of(work, struct epf_ntb, peer_db_work);
struct pci_epf *epf = ntb->epf;
unsigned int budget = VNTB_PEER_DB_WORK_BUDGET;
+ unsigned int irq_type;
u8 func_no, vfunc_no;
unsigned int db_bit;
u32 interrupt_num;
@@ -1540,6 +1561,7 @@ static void vntb_epf_peer_db_work(struct work_struct *work)
func_no = epf->func_no;
vfunc_no = epf->vfunc_no;
+ irq_type = ntb->peer_msix ? PCI_IRQ_MSIX : PCI_IRQ_MSI;
/*
* Drain doorbells from peer_db_pending in snapshots (atomic64_xchg()).
@@ -1553,16 +1575,16 @@ static void vntb_epf_peer_db_work(struct work_struct *work)
while (db_bits) {
/*
- * pci_epc_raise_irq() for MSI expects a 1-based
- * interrupt number. The first usable doorbell starts
- * at EPF_IRQ_DB_START in the legacy slot layout.
+ * pci_epc_raise_irq() expects a 1-based interrupt
+ * number for MSI and MSI-X. The first usable doorbell
+ * starts at EPF_IRQ_DB_START in the legacy slot layout.
*
* Legacy mapping (kept for compatibility):
*
- * MSI #1 : link event (reserved)
- * MSI #2 : unused (historical offset)
- * MSI #3 : doorbell bit 0 (DB#0)
- * MSI #4 : doorbell bit 1 (DB#1)
+ * IRQ #1 : link event (reserved)
+ * IRQ #2 : unused (historical offset)
+ * IRQ #3 : doorbell bit 0 (DB#0)
+ * IRQ #4 : doorbell bit 1 (DB#1)
* ...
*
* Do not change this mapping to avoid breaking
@@ -1573,7 +1595,7 @@ static void vntb_epf_peer_db_work(struct work_struct *work)
db_bits &= ~BIT_ULL(db_bit);
ret = pci_epc_raise_irq(epf->epc, func_no, vfunc_no,
- PCI_IRQ_MSI, interrupt_num);
+ irq_type, interrupt_num);
if (ret)
dev_err(&epf->dev,
"Failed to raise IRQ for interrupt_num %u: %d\n",
base-commit: 5cdbd6d3a3a147fa9975e35f2602cbec9a72a932
--
2.51.0