On Tue, 2024-10-01 at 16:33 -0300, Jason Gunthorpe wrote: > On Wed, Sep 25, 2024 at 07:49:59AM +0200, Jiri Slaby wrote: > > On 25. 09. 24, 7:29, Jiri Slaby wrote: > > > On 25. 09. 24, 7:06, Jiri Slaby wrote: > > > > > @@ -1047,23 +1066,33 @@ static void pci_std_enable_acs(struct > > > > > pci_dev *dev) > > > > > */ > > > > > static void pci_enable_acs(struct pci_dev *dev) > > > > > { > > > > > - if (!pci_acs_enable) > > > > > - goto disable_acs_redir; > > > > > + struct pci_acs caps; > > > > > + int pos; > > > > > + > > > > > + pos = dev->acs_cap; > > > > > + if (!pos) > > > > > + return; > > > > Ignore the previous post. > > > > The bridge has no ACS (see lspci below). So it used to be enabled > > by > > pci_quirk_enable_intel_pch_acs() by another registers. > > Er, Ok, so it overrides the whole thing with > pci_dev_specific_acs_enabled() too.. > > > I am not sure how to fix this as we cannot have "caps" from these > > quirks, so > > that whole idea of __pci_config_acs() is nonworking for these > > quirks. > > We just need to allow the quirk to run before we try to do anything > with the cap, which has probably always been a NOP anyhow. > > Maybe like this? > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 7d85c04fbba2ae..225a6cd2e9ca3b 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -1067,8 +1067,15 @@ static void pci_std_enable_acs(struct pci_dev > *dev, struct pci_acs *caps) > static void pci_enable_acs(struct pci_dev *dev) > { > struct pci_acs caps; > + bool enable_acs = false; > int pos; > > + /* If an iommu is present we start with kernel default caps > */ > + if (pci_acs_enable) { > + if (pci_dev_specific_enable_acs(dev)) > + enable_acs = true; > + } > + > pos = dev->acs_cap; > if (!pos) > return; > @@ -1077,11 +1084,8 @@ static void pci_enable_acs(struct pci_dev > *dev) > pci_read_config_word(dev, pos + PCI_ACS_CTRL, &caps.ctrl); > caps.fw_ctrl = caps.ctrl; > > - /* If an iommu is present we start with kernel default caps > */ > - if (pci_acs_enable) { > - if (pci_dev_specific_enable_acs(dev)) > - pci_std_enable_acs(dev, &caps); > - } > + if (enable_acs) > + pci_std_enable_acs(dev, &caps); > > /* > * Always apply caps from the command line, even if there is > no iommu. Hi, I just ran into this issue (fewer iommu groups starting with 6.11). Both reverting the original patch or applying your suggestion worked for me. Thanks Steffen