On Wed, Mar 23, 2016 at 04:01:58PM -0600, Jon Derrick wrote:
> This patch adds a hint, no_acpi, to the pci_host_bridge struct which
> informs the hotplug driver to not try and release the host bridge from
> acpi.
>
> The VMD driver creates a root port which does not have an acpi entry.
> This patch will allow the hotplug driver to bypass acpi release when
> enumerating the VMD root port as a hotplug slot.
I want to add a little context to this for the motivation for this
implementation.
Currently we have to set kernel parameter "pcie_ports=native" for pciehp
to work on these domains since they are not known to ACPI. We don't want
to force a system wide PCIe parameter for something specific to a subset
of domains.
If the implementation here sounds reasonable, I suggest having a helper
API function in pci to check for the host bridge requested acpi disabled.
> arch/x86/pci/vmd.c | 4 ++++
> drivers/pci/pcie/portdrv_acpi.c | 5 +++++
> include/linux/pci.h | 1 +
> 3 files changed, 10 insertions(+)
>
> diff --git a/arch/x86/pci/vmd.c b/arch/x86/pci/vmd.c
> index 7792aba..a196be3 100644
> --- a/arch/x86/pci/vmd.c
> +++ b/arch/x86/pci/vmd.c
> @@ -531,6 +531,7 @@ static int vmd_find_free_domain(void)
> static int vmd_enable_domain(struct vmd_dev *vmd)
> {
> struct pci_sysdata *sd = &vmd->sysdata;
> + struct pci_host_bridge *host_bridge;
> struct resource *res;
> u32 upper_bits;
> unsigned long flags;
> @@ -609,6 +610,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd)
> return -ENODEV;
> }
>
> + host_bridge = to_pci_host_bridge(vmd->bus->bridge);
> + host_bridge->no_acpi = true;
> +
> vmd_attach_resources(vmd);
> vmd_setup_dma_ops(vmd);
> dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
> diff --git a/drivers/pci/pcie/portdrv_acpi.c b/drivers/pci/pcie/portdrv_acpi.c
> index b4d2894..0e6fa69 100644
> --- a/drivers/pci/pcie/portdrv_acpi.c
> +++ b/drivers/pci/pcie/portdrv_acpi.c
> @@ -35,12 +35,17 @@
> int pcie_port_acpi_setup(struct pci_dev *port, int *srv_mask)
> {
> struct acpi_pci_root *root;
> + struct pci_host_bridge *host_bridge;
> acpi_handle handle;
> u32 flags;
>
> if (acpi_pci_disabled)
> return 0;
>
> + host_bridge = pci_find_host_bridge(port->bus);
> + if (host_bridge && host_bridge->no_acpi)
> + return 0;
> +
> handle = acpi_find_root_bridge_handle(port);
> if (!handle)
> return -EINVAL;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 15f466e..a6958e9b 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -407,6 +407,7 @@ struct pci_host_bridge {
> void (*release_fn)(struct pci_host_bridge *);
> void *release_data;
> unsigned int ignore_reset_delay:1; /* for entire hierarchy */
> + unsigned int no_acpi:1; /* bypasses acpi release */
> /* Resource alignment requirements */
> resource_size_t (*align_resource)(struct pci_dev *dev,
> const struct resource *res,
> --
> 1.8.3.1
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