On Tue, 2022-04-05 at 16:00 +0200, Rafael J. Wysocki wrote: > On Thu, Mar 31, 2022 at 10:20 PM Vishal Verma <vishal.l.verma@xxxxxxxxx> wrote: > > > > Add full support for negotiating _OSC as defined in the CXL 2.0 spec, as > > applicable to CXL-enabled platforms. Advertise support for the CXL > > features we support - 'CXL 2.0 port/device register access', 'Protocol > > Error Reporting', and 'CXL Native Hot Plug'. Request control for 'CXL > > Memory Error Reporting'. The requests are dependent on CONFIG_* based > > prerequisites, and prior PCI enabling, similar to how the standard PCI > > _OSC bits are determined. > > > > The CXL specification does not define any additional constraints on > > the hotplug flow beyond PCIe native hotplug, so a kernel that supports > > native PCIe hotplug, supports CXL hotplug. For error handling protocol > > and link errors just use PCIe AER. There is nascent support for > > amending AER events with CXL specific status [1], but there's > > otherwise no additional OS responsibility for CXL errors beyond PCIe > > AER. CXL Memory Errors behave the same as typical memory errors so > > CONFIG_MEMORY_FAILURE is sufficient to indicate support to platform > > firmware. > > > > [1]: https://lore.kernel.org/linux-cxl/164740402242.3912056.8303625392871313860.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > > > > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> > > Cc: Robert Moore <robert.moore@xxxxxxxxx> > > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > > Signed-off-by: Vishal Verma <vishal.l.verma@xxxxxxxxx> > > --- > > include/linux/acpi.h | 28 +++++++- > > include/acpi/acpi_bus.h | 6 +- > > drivers/acpi/pci_root.c | 145 ++++++++++++++++++++++++++++++++++------ > > 3 files changed, 157 insertions(+), 22 deletions(-) > > > > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > > index fc40da914315..cf360b9642d9 100644 > > --- a/include/linux/acpi.h > > +++ b/include/linux/acpi.h > > @@ -554,10 +554,15 @@ acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context); > > #define OSC_PCI_CAPABILITY_DWORDS 3 > > #define OSC_CXL_CAPABILITY_DWORDS 5 > > > > -/* Indexes into _OSC Capabilities Buffer (DWORDs 2 & 3 are device-specific) */ > > +/* > > + * Indexes into _OSC Capabilities Buffer > > + * DWORDs 2 & 3 are device-specific, and 4 & 5 are specific to CXL platforms > > Say "DWORDs 2 through 5 are device-specific" and you don't need to > mention CXL here. > > > + */ > > #define OSC_QUERY_DWORD 0 /* DWORD 1 */ > > #define OSC_SUPPORT_DWORD 1 /* DWORD 2 */ > > #define OSC_CONTROL_DWORD 2 /* DWORD 3 */ > > +#define OSC_CXL_SUPPORT_DWORD 3 /* DWORD 4 */ > > +#define OSC_CXL_CONTROL_DWORD 4 /* DWORD 5 */ > > I would rename the last two symbols as OSC_EXT_SUPPORT_DWORD and > OSC_EXT_CONTROL_DWORD (see below for an explanation). > > Yep, dropping CXL references here and the 'extended' naming sounds good, I'll update with these changes.
