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PCI: endpoint: pci-epf-vntb: Reject unusable doorbell counts

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pci-epf-vntb reserves slot 0 for link events and keeps slot 1 unused for
legacy layout compatibility. A db_count smaller than MIN_DB_COUNT leaves
no usable doorbell slot after those reservations.

Reject such configurations when configuring interrupts.

While at it, move MAX_DB_COUNT next to MIN_DB_COUNT. They are used as a
pair in the range check, and keeping them together makes the valid doorbell
range easier to read.

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/20260513024923.451765-5-den@valinux.co.jp
This commit is contained in:
Koichiro Den 2026-05-13 11:49:15 +09:00 committed by Bjorn Helgaas
parent 91fb4488cd
commit f417c400a6
1 changed files with 6 additions and 4 deletions
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10
drivers/pci/endpoint/functions/pci-epf-vntb.c
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@ -67,7 +67,6 @@ static struct workqueue_struct *kpcintb_workqueue;
#define NTB_MW_OFFSET 2
#define DB_COUNT_MASK GENMASK(15, 0)
#define MSIX_ENABLE BIT(16)
#define MAX_DB_COUNT 32
#define MAX_MW 4
/* Limit per-work execution to avoid monopolizing kworker on doorbell storms. */
@ -89,6 +88,9 @@ enum epf_irq_slot {
EPF_IRQ_DB_START,
};
#define MIN_DB_COUNT (EPF_IRQ_DB_START + 1)
#define MAX_DB_COUNT 32
/*
* +--------------------------------------------------+ Base
* | |
@ -512,9 +514,9 @@ static int epf_ntb_configure_interrupt(struct epf_ntb *ntb)
return -EINVAL;
}
if (!ntb->db_count || ntb->db_count > MAX_DB_COUNT) {
dev_err(dev, "DB count %d out of range (1 - %d)\n",
ntb->db_count, MAX_DB_COUNT);
if (ntb->db_count < MIN_DB_COUNT || ntb->db_count > MAX_DB_COUNT) {
dev_err(dev, "DB count %d out of range (%d - %d)\n",
ntb->db_count, MIN_DB_COUNT, MAX_DB_COUNT);
return -EINVAL;
}