| Message ID | 2b4c650d27e59c81903fa4c2526bf18a2cf2d243.1519882849.git.jan.kiszka@siemens.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Thu, Mar 1, 2018 at 7:40 AM, Jan Kiszka <jan.kiszka@siemens.com> wrote: > From: Jan Kiszka <jan.kiszka@siemens.com> > > Per PCIe r4.0, sec 7.5.1.1.9, multi-function devices are required to > have a function 0. Therefore, Linux scans for devices at function 0 > (devfn 0/8/16/...) and only scans for other functions if function 0 > has its Multi-Function Device bit set or ARI or SR-IOV indicate > there are more functions. > > The Jailhouse hypervisor may pass individual functions of a > multi-function device to a guest without passing function 0, which > means a Linux guest won't find them. > > Change Linux PCI probing so it scans all function numbers when > running as a guest over Jailhouse. > > This is technically prohibited by the spec, so it is possible that > PCI devices without the Multi-Function Device bit set may have > unexpected behavior in response to this probe. > > Derived from original patch by Benedikt Spranger. > FWIW, Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> One nit below. > CC: Benedikt Spranger <b.spranger@linutronix.de> > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> > Acked-by: Bjorn Helgaas <bhelgaas@google.com> > --- > arch/x86/pci/legacy.c | 4 +++- > drivers/pci/probe.c | 22 +++++++++++++++++++--- > 2 files changed, 22 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/pci/legacy.c b/arch/x86/pci/legacy.c > index 1cb01abcb1be..dfbe6ac38830 100644 > --- a/arch/x86/pci/legacy.c > +++ b/arch/x86/pci/legacy.c > @@ -4,6 +4,7 @@ > #include <linux/init.h> > #include <linux/export.h> > #include <linux/pci.h> > +#include <asm/jailhouse_para.h> > #include <asm/pci_x86.h> > > /* > @@ -34,13 +35,14 @@ int __init pci_legacy_init(void) > > void pcibios_scan_specific_bus(int busn) > { > + int stride = jailhouse_paravirt() ? 1 : 8; > int devfn; > u32 l; > > if (pci_find_bus(0, busn)) > return; > > - for (devfn = 0; devfn < 256; devfn += 8) { > + for (devfn = 0; devfn < 256; devfn += stride) { > if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &l) && > l != 0x0000 && l != 0xffff) { > DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, l); > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index ef5377438a1e..da22d6d216f8 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -16,6 +16,7 @@ > #include <linux/pci-aspm.h> > #include <linux/aer.h> > #include <linux/acpi.h> > +#include <linux/hypervisor.h> > #include <linux/irqdomain.h> > #include <linux/pm_runtime.h> > #include "pci.h" > @@ -2518,14 +2519,29 @@ static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus, > { > unsigned int used_buses, normal_bridges = 0, hotplug_bridges = 0; > unsigned int start = bus->busn_res.start; > - unsigned int devfn, cmax, max = start; > + unsigned int devfn, fn, cmax, max = start; > struct pci_dev *dev; > + int nr_devs; > > dev_dbg(&bus->dev, "scanning bus\n"); > > /* Go find them, Rover! */ > - for (devfn = 0; devfn < 0x100; devfn += 8) > - pci_scan_slot(bus, devfn); > + for (devfn = 0; devfn < 0x100; devfn += 8) { Since you touch this line perhaps make sense to unify with above, i.e. 0x100 -> 256 ? > + nr_devs = pci_scan_slot(bus, devfn); > + > + /* > + * The Jailhouse hypervisor may pass individual functions of a > + * multi-function device to a guest without passing function 0. > + * Look for them as well. > + */ > + if (jailhouse_paravirt() && nr_devs == 0) { > + for (fn = 1; fn < 8; fn++) { > + dev = pci_scan_single_device(bus, devfn + fn); > + if (dev) > + dev->multifunction = 1; > + } > + } > + } > > /* Reserve buses for SR-IOV capability */ > used_buses = pci_iov_bus_range(bus); > -- > 2.13.6 >
diff --git a/arch/x86/pci/legacy.c b/arch/x86/pci/legacy.c index 1cb01abcb1be..dfbe6ac38830 100644 --- a/arch/x86/pci/legacy.c +++ b/arch/x86/pci/legacy.c @@ -4,6 +4,7 @@ #include <linux/init.h> #include <linux/export.h> #include <linux/pci.h> +#include <asm/jailhouse_para.h> #include <asm/pci_x86.h> /* @@ -34,13 +35,14 @@ int __init pci_legacy_init(void) void pcibios_scan_specific_bus(int busn) { + int stride = jailhouse_paravirt() ? 1 : 8; int devfn; u32 l; if (pci_find_bus(0, busn)) return; - for (devfn = 0; devfn < 256; devfn += 8) { + for (devfn = 0; devfn < 256; devfn += stride) { if (!raw_pci_read(0, busn, devfn, PCI_VENDOR_ID, 2, &l) && l != 0x0000 && l != 0xffff) { DBG("Found device at %02x:%02x [%04x]\n", busn, devfn, l); diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index ef5377438a1e..da22d6d216f8 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -16,6 +16,7 @@ #include <linux/pci-aspm.h> #include <linux/aer.h> #include <linux/acpi.h> +#include <linux/hypervisor.h> #include <linux/irqdomain.h> #include <linux/pm_runtime.h> #include "pci.h" @@ -2518,14 +2519,29 @@ static unsigned int pci_scan_child_bus_extend(struct pci_bus *bus, { unsigned int used_buses, normal_bridges = 0, hotplug_bridges = 0; unsigned int start = bus->busn_res.start; - unsigned int devfn, cmax, max = start; + unsigned int devfn, fn, cmax, max = start; struct pci_dev *dev; + int nr_devs; dev_dbg(&bus->dev, "scanning bus\n"); /* Go find them, Rover! */ - for (devfn = 0; devfn < 0x100; devfn += 8) - pci_scan_slot(bus, devfn); + for (devfn = 0; devfn < 0x100; devfn += 8) { + nr_devs = pci_scan_slot(bus, devfn); + + /* + * The Jailhouse hypervisor may pass individual functions of a + * multi-function device to a guest without passing function 0. + * Look for them as well. + */ + if (jailhouse_paravirt() && nr_devs == 0) { + for (fn = 1; fn < 8; fn++) { + dev = pci_scan_single_device(bus, devfn + fn); + if (dev) + dev->multifunction = 1; + } + } + } /* Reserve buses for SR-IOV capability */ used_buses = pci_iov_bus_range(bus);