Re: [PATCH v6 0/3] PCI/ACPI: add support for CXL _OSC

["Verma, Vishal L" <vishal.l.verma@intel.com>]

On Wed, 2022-04-13 at 01:36 -0600, Vishal Verma wrote:
> Changes since v5[1]:
> - Collect an reviewed-by tags from Rafael, Adam, and David
> - Fix a couple of missed s/CXL/extended/ in acpi_bus.h (Rafael)

Rafael, or Bjorn,

Dan has offered to take this through cxl.git. Any objections to that -
would you prefer it to go through either the PCI or ACPI trees instead?

> 
> Add support for using the CXL definition of _OSC where applicable, and
> negotiating CXL specific support and control bits.
> 
> Patch 1 is a preliminary cleanup that replaces open-coded pointer
> arithmetic to retrieve the Control DWORD with an inline helper.
> 
> Patch 2 adds the new CXL _OSC UUID, and uses it instead of the PCI UUID
> when a root port is CXL enabled. It provides a fallback method for
> CXL-1.1 platforms that may not implement the CXL-2.0 _OSC.
> 
> Patch 3 performs negotiation for the CXL specific _OSC support and
> control bits.
> 
> I've tested these against a custom qemu[2], which adds the CXL _OSC (in
> addition to other CXL support). Specifically, _OSC support is added
> here[3].
> 
> [1]: https://lore.kernel.org/linux-cxl/20220406023746.2807328-1-vishal.l.verma@intel.com
> [2]: https://gitlab.com/jic23/qemu/-/tree/cxl-v8-draft
> [3]: https://gitlab.com/jic23/qemu/-/commit/1d67df6b6e3716c27462873f3451956f5c0673a3
> 
> Dan Williams (1):
>   PCI/ACPI: Prefer CXL _OSC instead of PCIe _OSC for CXL host bridges
> 
> Vishal Verma (2):
>   PCI/ACPI: add a helper for retrieving _OSC Control DWORDs
>   PCI/ACPI: negotiate CXL _OSC
> 
>  include/linux/acpi.h    |  42 ++++++-
>  include/acpi/acpi_bus.h |  12 +-
>  drivers/acpi/bus.c      |   2 +-
>  drivers/acpi/pci_root.c | 240 +++++++++++++++++++++++++++++++++++-----
>  4 files changed, 262 insertions(+), 34 deletions(-)
> 
> 
> base-commit: 05e815539f3f161585c13a9ab023341bade2c52f