git: 31776afdc79d - main - pci_pci: Support growing bus ranges in bus_adjust_resource for NEW_PCIB

[Jessica Clarke]

The branch main has been updated by jrtc27:

URL: https://cgit.FreeBSD.org/src/commit/?id=31776afdc79d5fb1ea211cc2a69c17c62b3dc8ff

commit 31776afdc79d5fb1ea211cc2a69c17c62b3dc8ff
Author:     Jessica Clarke <jrtc27 at FreeBSD.org>
AuthorDate: 2021-10-03 18:35:26 +0000
Commit:     Jessica Clarke <jrtc27 at FreeBSD.org>
CommitDate: 2021-10-03 18:35:26 +0000

    pci_pci: Support growing bus ranges in bus_adjust_resource for NEW_PCIB
    
    This is the same underlying problem as 262459806433, just for bus ranges
    rather than windows. SiFive's HiFive Unmatched has the following
    topology:
    
      Root Port <---> Bridge <---> Bridge <-+-> Bridge <---> (Unused)
       (pcib0)        (pcib1)      (pcib2)  |   (pcib3)
                                            +-> Bridge <---> xHCI
                                            |   (pcib4)
                                            +-> Bridge <---> M.2 E-key
                                            |   (pcib5)
                                            +-> Bridge <---> M.2 M-key
                                            |   (pcib6)
                                            +-> Bridge <---> x16 slot
                                                (pcib7)
    
    If a device is plugged into the x16 slot that itself has a bridge, such
    as many graphics cards, we currently fail to allocate a bus number for
    its child bus (and so pcib_attach_child skips adding a child bus for
    further enumeration) as, when the new child bridge attaches, it attempts
    to allocate a bus number from its parent (pcib7) which in turn attempts
    to grow its own bus range by calling bus_adjust_resource on its own
    parent (pcib2) whose bus rman cannot accommodate the request and needs
    to itself be extended by calling its own parent (pcib1). Note that
    pcib3-7 do not face the same issue when they attach since pcib1 ends up
    managing bus numbers 1-255 from the beginning and so never needs to grow
    its own range.
    
    Reviewed by:    jhb, mav
    MFC after:      1 week
    Differential Revision:  https://reviews.freebsd.org/D32011
---
 sys/dev/pci/pci_pci.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/sys/dev/pci/pci_pci.c b/sys/dev/pci/pci_pci.c
index 2b86f2f50e11..cecf75024d3f 100644
--- a/sys/dev/pci/pci_pci.c
+++ b/sys/dev/pci/pci_pci.c
@@ -2364,7 +2364,20 @@ pcib_adjust_resource(device_t bus, device_t child, int type, struct resource *r,
 		    start, end));
 
 #ifdef PCI_RES_BUS
-	if (type != PCI_RES_BUS)
+	if (type == PCI_RES_BUS) {
+		/*
+		 * If our bus range isn't big enough to grow the sub-allocation
+		 * then we need to grow our bus range. Any request that would
+		 * require us to decrease the start of our own bus range is
+		 * invalid, we can only extend the end; ignore such requests
+		 * and let rman_adjust_resource fail below.
+		 */
+		if (start >= sc->bus.sec && end > sc->bus.sub) {
+			error = pcib_grow_subbus(&sc->bus, end);
+			if (error != 0)
+				return (error);
+		}
+	} else
 #endif
 	{
 		/*