On Fri, Nov 19, 2021 at 01:48:59PM -0700, Patel, Nirmal wrote:
> On 11/16/2021 3:11 PM, Nirmal Patel wrote:
> > During VT-d pass-through, the VMD driver occasionally fails to
> > enumerate underlying NVMe devices when repetitive reboots are
> > performed in the guest OS. The issue can be resolved by resetting
> > VMD root ports for proper enumeration and triggering secondary bus
> > reset which will also propagate reset through downstream bridges.
> >
> > Signed-off-by: Nirmal Patel <nirmal.patel@xxxxxxxxxxxxxxx>
> > Reviewed-by: Jon Derrick <jonathan.derrick@xxxxxxxxx>
> > ---
> > ---
> > v4->v5: Fixing small nitpick fix.
> > v3->v4: Using pci_reset_bus function for secondary bus reset instead of
> > manually triggering secondary bus reset, addressing review
> > comments of v3.
> > v2->v3: Combining two functions into one, Remove redundant definations
> > and Formatting fixes
> >
> > drivers/pci/controller/vmd.c | 37 ++++++++++++++++++++++++++++++++++++
> > 1 file changed, 37 insertions(+)
> >
> > diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> > index a5987e52700e..a905fce6232f 100644
> > --- a/drivers/pci/controller/vmd.c
> > +++ b/drivers/pci/controller/vmd.c
> > @@ -498,6 +498,40 @@ static inline void vmd_acpi_begin(void) { }
> > static inline void vmd_acpi_end(void) { }
> > #endif /* CONFIG_ACPI */
> >
> > +static void vmd_domain_reset(struct vmd_dev *vmd)
> > +{
> > + u16 bus, max_buses = resource_size(&vmd->resources[0]);
> > + u8 dev, functions, fn, hdr_type;
> > + char __iomem *base;
> > +
> > + for (bus = 0; bus < max_buses; bus++) {
> > + for (dev = 0; dev < 32; dev++) {
> > + base = vmd->cfgbar + PCIE_ECAM_OFFSET(bus,
> > + PCI_DEVFN(dev, 0), 0);
> > +
> > + hdr_type = readb(base + PCI_HEADER_TYPE) &
> > + PCI_HEADER_TYPE_MASK;
> > +
> > + functions = (hdr_type & 0x80) ? 8 : 1;
> > + for (fn = 0; fn < functions; fn++) {
> > + base = vmd->cfgbar + PCIE_ECAM_OFFSET(bus,
> > + PCI_DEVFN(dev, fn), 0);
> > +
> > + hdr_type = readb(base + PCI_HEADER_TYPE) &
> > + PCI_HEADER_TYPE_MASK;
> > +
> > + if (hdr_type != PCI_HEADER_TYPE_BRIDGE ||
> > + (readw(base + PCI_CLASS_DEVICE) !=
> > + PCI_CLASS_BRIDGE_PCI))
> > + continue;
> > +
> > + memset_io(base + PCI_IO_BASE, 0,
> > + PCI_ROM_ADDRESS1 - PCI_IO_BASE);
> > + }
> > + }
> > + }
> > +}
> > +
> > static void vmd_attach_resources(struct vmd_dev *vmd)
> > {
> > vmd->dev->resource[VMD_MEMBAR1].child = &vmd->resources[1];
> > @@ -801,6 +835,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
> > vmd_acpi_begin();
> >
> > pci_scan_child_bus(vmd->bus);
> > + vmd_domain_reset(vmd);
> > + list_for_each_entry(child, &vmd->bus->children, node)
> > + pci_reset_bus(child->self);
> > pci_assign_unassigned_bus_resources(vmd->bus);
> >
> > /*
>
> Hi
>
> Gentle ping. Please let me know if you are okay with these changes
> (with Jon's Reviewed-by). Thanks.
This got assigned to me by mistake, so I just reassigned it to Lorenzo
in patchwork. There's no hurry, we're only at v5.16-rc1. It doesn't
appear to be a candidate for v5.16, and there's always "cc: stable" if
appropriate.
Bjorn
