On 10/25/2021 11:29 AM, 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>
> ---
> 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..79f8b86ee45b 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.
-nirmal
