From 20d25779c8eab9e21668a18a6180d75775f4eaee Mon Sep 17 00:00:00 2001 From: Arthur Heymans Date: Wed, 17 Nov 2021 17:25:48 +0100 Subject: [PATCH] device/pci_device.c: Add way to limit max bus numbers By default this limits PCI buses to CONFIG_MMCONF_BUS_NUMBER. Some platforms have multiple PCI root busses (e.g. xeon_sp), where bus numbers are limited. This provides a basic check. On some platforms it looks like programming 0xff to the subordinate bus number confuses and hangs the hardware. Change-Id: I0582b156df1a5f76119a3687886c4d58f2d3ad6f Signed-off-by: Arthur Heymans Reviewed-on: https://review.coreboot.org/c/coreboot/+/59395 Tested-by: build bot (Jenkins) Reviewed-by: Jonathan Zhang Reviewed-by: David Hendricks --- src/device/pci_device.c | 14 +++++++++++++- src/include/device/device.h | 3 ++- 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/src/device/pci_device.c b/src/device/pci_device.c index 9de294698a..e600f34fe6 100644 --- a/src/device/pci_device.c +++ b/src/device/pci_device.c @@ -1532,6 +1532,18 @@ static void pci_bridge_route(struct bus *link, scan_state state) if (state == PCI_ROUTE_SCAN) { link->secondary = parent->subordinate + 1; link->subordinate = link->secondary + dev->hotplug_buses; + link->max_subordinate = parent->max_subordinate + ? parent->max_subordinate + : (CONFIG_ECAM_MMCONF_BUS_NUMBER - 1); + } + + if (link->secondary > link->max_subordinate) + die("%s: No more busses available!\n", __func__); + + /* This ought to only happen with hotplug buses. */ + if (link->subordinate > link->max_subordinate) { + printk(BIOS_WARNING, "%s: Limiting subordinate busses\n", __func__); + link->subordinate = link->max_subordinate; } if (state == PCI_ROUTE_CLOSE) { @@ -1541,7 +1553,7 @@ static void pci_bridge_route(struct bus *link, scan_state state) } else if (state == PCI_ROUTE_SCAN) { primary = parent->secondary; secondary = link->secondary; - subordinate = 0xff; /* MAX PCI_BUS number here */ + subordinate = link->max_subordinate; } else if (state == PCI_ROUTE_FINAL) { primary = parent->secondary; secondary = link->secondary; diff --git a/src/include/device/device.h b/src/include/device/device.h index 8b1dde1109..b4b2d20e11 100644 --- a/src/include/device/device.h +++ b/src/include/device/device.h @@ -85,7 +85,8 @@ struct bus { uint16_t bridge_cmd; /* Bridge command register */ unsigned char link_num; /* The index of this link */ uint16_t secondary; /* secondary bus number */ - uint16_t subordinate; /* max subordinate bus number */ + uint16_t subordinate; /* subordinate bus number */ + uint16_t max_subordinate; /* max subordinate bus number */ unsigned char cap; /* PCi capability offset */ uint32_t hcdn_reg; /* For HyperTransport link */