From 823468a4ea1613f1c1235bd16af8b9c6eb9c9677 Mon Sep 17 00:00:00 2001 From: Koichiro Den Date: Wed, 13 May 2026 11:49:17 +0900 Subject: [PATCH] PCI: endpoint: pci-epf-vntb: Exclude reserved slots from db_valid_mask In pci-epf-vntb, db_count represents the total number of doorbell slots exposed to the peer, including: - slot #0 reserved for link events, and - slot #1 historically unused (kept for compatibility). Only the remaining slots correspond to actual doorbell bits. The current db_valid_mask() exposes all slots as valid doorbells. Limit db_valid_mask() to the real doorbell bits by returning BIT_ULL(db_count - 2) - 1, and guard against db_count < 2. Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP") Signed-off-by: Koichiro Den Signed-off-by: Manivannan Sadhasivam Signed-off-by: Bjorn Helgaas Reviewed-by: Frank Li Link: https://patch.msgid.link/20260513024923.451765-7-den@valinux.co.jp --- drivers/pci/endpoint/functions/pci-epf-vntb.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c index 524355a8b4be..58e41d95d029 100644 --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c @@ -1364,7 +1364,10 @@ static int vntb_epf_peer_mw_count(struct ntb_dev *ntb) static u64 vntb_epf_db_valid_mask(struct ntb_dev *ntb) { - return BIT_ULL(ntb_ndev(ntb)->db_count) - 1; + if (ntb_ndev(ntb)->db_count < EPF_IRQ_DB_START) + return 0; + + return BIT_ULL(ntb_ndev(ntb)->db_count - EPF_IRQ_DB_START) - 1; } static int vntb_epf_db_set_mask(struct ntb_dev *ntb, u64 db_bits)