On Tue, Jan 29, 2019 at 05:47:32PM -0500, Michael S. Tsirkin wrote: > On Tue, Jan 29, 2019 at 04:43:33PM -0600, Bjorn Helgaas wrote: > > On Tue, Jan 22, 2019 at 01:02:54PM -0600, Bjorn Helgaas wrote: > > > From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > > > > > pci_bridge_check_ranges() determines whether a bridge supports the optional > > > I/O and prefetchable memory windows and sets the flag bits in the bridge > > > resources. This *could* be done once during enumeration except that the > > > resource allocation code completely clears the flag bits, e.g., in the > > > pci_assign_unassigned_bridge_resources() path. > > > > > > The problem with pci_bridge_check_ranges() in the resource allocation path > > > is that we may allocate resources after devices have been claimed by > > > drivers, and pci_bridge_check_ranges() *changes* the window registers to > > > determine whether they're writable. This may break concurrent accesses to > > > devices behind the bridge. > > > > > > Add a new pci_read_bridge_windows() to determine whether a bridge supports > > > the optional windows, call it once during enumeration, remember the > > > results, and change pci_bridge_check_ranges() so it doesn't touch the > > > bridge windows but sets the flag bits based on those remembered results. > > > > > > Link: https://lore.kernel.org/linux-pci/1506151482-113560-1-git-send-email-wangzhou1@xxxxxxxxxxxxx > > > Link: https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg02082.html > > > Reported-by: xuyandong <xuyandong2@xxxxxxxxxx> > > > Tested-by: xuyandong <xuyandong2@xxxxxxxxxx> > > > Cc: Sagi Grimberg <sagi@xxxxxxxxxxx> > > > Cc: Ofer Hayut <ofer@xxxxxxxxxxxxxxxxx> > > > Cc: Roy Shterman <roys@xxxxxxxxxxxxxxxxx> > > > Cc: Keith Busch <keith.busch@xxxxxxxxx> > > > Cc: Zhou Wang <wangzhou1@xxxxxxxxxxxxx> > > > > Applied to pci/enumeration for v5.1. > > > > This is fairly simple in concept, but doesn't meet the letter of the > > restrictions in Documentation/process/stable-kernel-rules.rst, so I > > didn't tag it for stable. > > > > Is there a compelling argument to mark it for stable? > > Well it's needed downstream. > It's a bit above 100 lines with context. Is this what you mean? Yep, I should have been explicit about that. > If yes how about using my patch for stable as an alternative? > The rules allow for equivalent patches. Well, yes, that would be a possibility. I would rather develop an argument for marking *this* patch for stable. Even though it is technically too large, I think we could make it work if we have compelling reasons. Those would need to be fleshed out a little more than "needed downstream" -- something about the scenarios where this happens, what the serious problem is, etc. The *ideal* thing would be to have an actual bugzilla.kernel.org report of the problem with a way to reproduce it and dmesg illustrating the problem. > > > --- > > > drivers/pci/probe.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++ > > > drivers/pci/setup-bus.c | 45 ++++------------------------------------- > > > include/linux/pci.h | 3 +++ > > > 3 files changed, 59 insertions(+), 41 deletions(-) > > > > > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > > > index 257b9f6f2ebb..2ef8b954c65a 100644 > > > --- a/drivers/pci/probe.c > > > +++ b/drivers/pci/probe.c > > > @@ -348,6 +348,57 @@ static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom) > > > } > > > } > > > > > > +static void pci_read_bridge_windows(struct pci_dev *bridge) > > > +{ > > > + u16 io; > > > + u32 pmem, tmp; > > > + > > > + pci_read_config_word(bridge, PCI_IO_BASE, &io); > > > + if (!io) { > > > + pci_write_config_word(bridge, PCI_IO_BASE, 0xe0f0); > > > + pci_read_config_word(bridge, PCI_IO_BASE, &io); > > > + pci_write_config_word(bridge, PCI_IO_BASE, 0x0); > > > + } > > > + if (io) > > > + bridge->io_window = 1; > > > + > > > + /* > > > + * DECchip 21050 pass 2 errata: the bridge may miss an address > > > + * disconnect boundary by one PCI data phase. Workaround: do not > > > + * use prefetching on this device. > > > + */ > > > + if (bridge->vendor == PCI_VENDOR_ID_DEC && bridge->device == 0x0001) > > > + return; > > > + > > > + pci_read_config_dword(bridge, PCI_PREF_MEMORY_BASE, &pmem); > > > + if (!pmem) { > > > + pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, > > > + 0xffe0fff0); > > > + pci_read_config_dword(bridge, PCI_PREF_MEMORY_BASE, &pmem); > > > + pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, 0x0); > > > + } > > > + if (!pmem) > > > + return; > > > + > > > + bridge->pref_window = 1; > > > + > > > + if ((pmem & PCI_PREF_RANGE_TYPE_MASK) == PCI_PREF_RANGE_TYPE_64) { > > > + > > > + /* > > > + * Bridge claims to have a 64-bit prefetchable memory > > > + * window; verify that the upper bits are actually > > > + * writable. > > > + */ > > > + pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, &pmem); > > > + pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, > > > + 0xffffffff); > > > + pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, &tmp); > > > + pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, pmem); > > > + if (tmp) > > > + bridge->pref_64_window = 1; > > > + } > > > +} > > > + > > > static void pci_read_bridge_io(struct pci_bus *child) > > > { > > > struct pci_dev *dev = child->self; > > > @@ -1739,6 +1790,7 @@ int pci_setup_device(struct pci_dev *dev) > > > pci_read_irq(dev); > > > dev->transparent = ((dev->class & 0xff) == 1); > > > pci_read_bases(dev, 2, PCI_ROM_ADDRESS1); > > > + pci_read_bridge_windows(dev); > > > set_pcie_hotplug_bridge(dev); > > > pos = pci_find_capability(dev, PCI_CAP_ID_SSVID); > > > if (pos) { > > > diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c > > > index ed960436df5e..1941bb0a6c13 100644 > > > --- a/drivers/pci/setup-bus.c > > > +++ b/drivers/pci/setup-bus.c > > > @@ -735,58 +735,21 @@ int pci_claim_bridge_resource(struct pci_dev *bridge, int i) > > > base/limit registers must be read-only and read as 0. */ > > > static void pci_bridge_check_ranges(struct pci_bus *bus) > > > { > > > - u16 io; > > > - u32 pmem; > > > struct pci_dev *bridge = bus->self; > > > - struct resource *b_res; > > > + struct resource *b_res = &bridge->resource[PCI_BRIDGE_RESOURCES]; > > > > > > - b_res = &bridge->resource[PCI_BRIDGE_RESOURCES]; > > > b_res[1].flags |= IORESOURCE_MEM; > > > > > > - pci_read_config_word(bridge, PCI_IO_BASE, &io); > > > - if (!io) { > > > - pci_write_config_word(bridge, PCI_IO_BASE, 0xe0f0); > > > - pci_read_config_word(bridge, PCI_IO_BASE, &io); > > > - pci_write_config_word(bridge, PCI_IO_BASE, 0x0); > > > - } > > > - if (io) > > > + if (bridge->io_window) > > > b_res[0].flags |= IORESOURCE_IO; > > > > > > - /* DECchip 21050 pass 2 errata: the bridge may miss an address > > > - disconnect boundary by one PCI data phase. > > > - Workaround: do not use prefetching on this device. */ > > > - if (bridge->vendor == PCI_VENDOR_ID_DEC && bridge->device == 0x0001) > > > - return; > > > - > > > - pci_read_config_dword(bridge, PCI_PREF_MEMORY_BASE, &pmem); > > > - if (!pmem) { > > > - pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, > > > - 0xffe0fff0); > > > - pci_read_config_dword(bridge, PCI_PREF_MEMORY_BASE, &pmem); > > > - pci_write_config_dword(bridge, PCI_PREF_MEMORY_BASE, 0x0); > > > - } > > > - if (pmem) { > > > + if (bridge->pref_window) { > > > b_res[2].flags |= IORESOURCE_MEM | IORESOURCE_PREFETCH; > > > - if ((pmem & PCI_PREF_RANGE_TYPE_MASK) == > > > - PCI_PREF_RANGE_TYPE_64) { > > > + if (bridge->pref_64_window) { > > > b_res[2].flags |= IORESOURCE_MEM_64; > > > b_res[2].flags |= PCI_PREF_RANGE_TYPE_64; > > > } > > > } > > > - > > > - /* double check if bridge does support 64 bit pref */ > > > - if (b_res[2].flags & IORESOURCE_MEM_64) { > > > - u32 mem_base_hi, tmp; > > > - pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, > > > - &mem_base_hi); > > > - pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, > > > - 0xffffffff); > > > - pci_read_config_dword(bridge, PCI_PREF_BASE_UPPER32, &tmp); > > > - if (!tmp) > > > - b_res[2].flags &= ~IORESOURCE_MEM_64; > > > - pci_write_config_dword(bridge, PCI_PREF_BASE_UPPER32, > > > - mem_base_hi); > > > - } > > > } > > > > > > /* Helper function for sizing routines: find first available > > > diff --git a/include/linux/pci.h b/include/linux/pci.h > > > index 65f1d8c2f082..40b327b814aa 100644 > > > --- a/include/linux/pci.h > > > +++ b/include/linux/pci.h > > > @@ -373,6 +373,9 @@ struct pci_dev { > > > bool match_driver; /* Skip attaching driver */ > > > > > > unsigned int transparent:1; /* Subtractive decode bridge */ > > > + unsigned int io_window:1; /* Bridge has I/O window */ > > > + unsigned int pref_window:1; /* Bridge has pref mem window */ > > > + unsigned int pref_64_window:1; /* Pref mem window is 64-bit */ > > > unsigned int multifunction:1; /* Multi-function device */ > > > > > > unsigned int is_busmaster:1; /* Is busmaster */ > > >
