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PCI: endpoint: pci-epf-vntb: Exclude reserved slots from db_valid_mask

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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: e35f56bb03 ("PCI: endpoint: Support NTB transfer between RC and EP")
Signed-off-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260513024923.451765-7-den@valinux.co.jp
This commit is contained in:
Koichiro Den 2026-05-13 11:49:17 +09:00 committed by Bjorn Helgaas
parent 6c39350aaa
commit 823468a4ea
1 changed files with 4 additions and 1 deletions
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5
drivers/pci/endpoint/functions/pci-epf-vntb.c
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@ -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)