Re: [PATCH v9 6/9] PCI/bwctrl: Re-add BW notification portdrv as PCIe BW controller

[Niklas Schnelle <niks@kernel.org>]

On Fri, 2024-12-06 at 19:12 +0100, Niklas Schnelle wrote:
> On Fri, 2024-10-18 at 17:47 +0300, Ilpo Järvinen wrote:
> > This mostly reverts the commit b4c7d2076b4e ("PCI/LINK: Remove
> > bandwidth notification"). An upcoming commit extends this driver
> > building PCIe bandwidth controller on top of it.
> > 
> > The PCIe bandwidth notification were first added in the commit
> > e8303bb7a75c ("PCI/LINK: Report degraded links via link bandwidth
> > notification") but later had to be removed. The significant changes
> > compared with the old bandwidth notification driver include:
> > 
---8<---
> > ---
> 
> Hi Ilpo,
> 
> I bisected a v6.13-rc1 boot hang on my personal workstation to this
> patch. Sadly I don't have much details like a panic or so because the
> boot hangs before any kernel messages, or at least they're not visible
> long enough to see. I haven't yet looked into the code as I wanted to
> raise awareness first. Since the commit doesn't revert cleanly on
> v6.13-rc1 I also haven't tried that yet.
> 
> Here are some details on my system:
> - AMD Ryzen 9 3900X 
> - ASRock X570 Creator Motherboard
> - Radeon RX 5600 XT
> - Intel JHL7540 Thunderbolt 3 USB Controller (only USB 2 plugged)
> - Intel 82599 10 Gigabit NIC with SR-IOV enabled with 2 VFs
> - Intel n I211 Gigabit NIC
> - Intel Wi-Fi 6 AX200
> - Aquantia AQtion AQC107 NIC
> 
> If you have patches or things to try just ask.
> 
> Thanks,
> Niklas
> 

Ok I can now at least confirm that bluntly disabling the new bwctrl
driver with the below diff on top of v6.13-rc1 circumvents the boot
hang I'm seeing. So it's definitely this.

diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
index 5e10306b6308..6fa54480444a 100644
--- a/drivers/pci/pcie/portdrv.c
+++ b/drivers/pci/pcie/portdrv.c
@@ -828,7 +828,7 @@ static void __init pcie_init_services(void)
        pcie_aer_init();
        pcie_pme_init();
        pcie_dpc_init();
-       pcie_bwctrl_init();
+       /* pcie_bwctrl_init(); */
        pcie_hp_init();
 }