On Fri, Mar 18, 2022 at 2:30 PM Vishal Verma <vishal.l.verma@xxxxxxxxx> wrote: > > From: Dan Williams <dan.j.williams@xxxxxxxxx> Oh, you dropped the first paragraph. When I said "I would replace" in my comment [1] I was only referring to the light-on-details second paragraph, so prepend this for the final version of the patch: In preparation for negotiating OS control of CXL _OSC features, do the minimal enabling to use CXL _OSC to handle the base PCIe feature negotiation. Recall that CXL _OSC is a super-set of PCIe _OSC and the CXL 2.0 specification mandates: "If a CXL Host Bridge device exposes CXL _OSC, CXL aware OSPM shall evaluate CXL _OSC and not evaluate PCIe _OSC." [1]: https://lore.kernel.org/r/CAPcyv4h581oXv59Praskpyk6ywPBm1ksxT4YPvZiv80F6ugZnw@xxxxxxxxxxxxxx > > Rather than pass a boolean flag alongside @root to all the helper > functions that need to consider PCIe specifics, add is_pcie() and > is_cxl() helper functions to check the flavor of @root. This also > allows for dynamic fallback to PCIe _OSC in cases where an attempt to > use CXL _OXC fails. This can happen on CXL 1.1 platforms that publish > ACPI0016 devices to indicate CXL host bridges, but do not publish the > optional CXL _OSC method. CXL _OSC is mandatory for CXL 2.0 hosts. > > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> > Cc: Robert Moore <robert.moore@xxxxxxxxx> > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> > Signed-off-by: Vishal Verma <vishal.l.verma@xxxxxxxxx> > --- > include/acpi/acpi_bus.h | 1 + > drivers/acpi/pci_root.c | 62 +++++++++++++++++++++++++++++++---------- > 2 files changed, 48 insertions(+), 15 deletions(-) > > diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h > index ca88c4706f2b..768ef1584055 100644 > --- a/include/acpi/acpi_bus.h > +++ b/include/acpi/acpi_bus.h > @@ -585,6 +585,7 @@ struct acpi_pci_root { > struct acpi_device * device; > struct pci_bus *bus; > u16 segment; > + bool cxl_osc_disable; > struct resource secondary; /* downstream bus range */ > > u32 osc_support_set; /* _OSC state of support bits */ > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c > index b76db99cced3..2d834504096b 100644 > --- a/drivers/acpi/pci_root.c > +++ b/drivers/acpi/pci_root.c > @@ -170,20 +170,47 @@ static void decode_osc_control(struct acpi_pci_root *root, char *msg, u32 word) > ARRAY_SIZE(pci_osc_control_bit)); > } > > -static u8 pci_osc_uuid_str[] = "33DB4D5B-1FF7-401C-9657-7441C03DD766"; > +static bool is_pcie(struct acpi_pci_root *root) > +{ > + return strcmp(acpi_device_hid(root->device), "PNP0A08") == 0; > +} > > -static acpi_status acpi_pci_run_osc(acpi_handle handle, > +static bool is_cxl(struct acpi_pci_root *root) > +{ > + if (root->cxl_osc_disable) > + return false; > + return strcmp(acpi_device_hid(root->device), "ACPI0016") == 0; > +} > + > +static u8 pci_osc_uuid_str[] = "33DB4D5B-1FF7-401C-9657-7441C03DD766"; > +static u8 cxl_osc_uuid_str[] = "68F2D50B-C469-4d8A-BD3D-941A103FD3FC"; > + > +static char *to_uuid(struct acpi_pci_root *root) > +{ > + if (is_cxl(root)) > + return cxl_osc_uuid_str; > + return pci_osc_uuid_str; > +} > + > +static int cap_length(struct acpi_pci_root *root) > +{ > + if (is_cxl(root)) > + return sizeof(u32) * 6; > + return sizeof(u32) * 3; > +} > + > +static acpi_status acpi_pci_run_osc(struct acpi_pci_root *root, > const u32 *capbuf, u32 *retval) > { > struct acpi_osc_context context = { > - .uuid_str = pci_osc_uuid_str, > + .uuid_str = to_uuid(root), > .rev = 1, > - .cap.length = 12, > + .cap.length = cap_length(root), > .cap.pointer = (void *)capbuf, > }; > acpi_status status; > > - status = acpi_run_osc(handle, &context); > + status = acpi_run_osc(root->device->handle, &context); > if (ACPI_SUCCESS(status)) { > *retval = *((u32 *)(context.ret.pointer + 8)); > kfree(context.ret.pointer); > @@ -196,7 +223,7 @@ static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root, > u32 *control) > { > acpi_status status; > - u32 result, capbuf[3]; > + u32 result, capbuf[6]; > > support |= root->osc_support_set; > > @@ -204,10 +231,18 @@ static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root, > capbuf[OSC_SUPPORT_DWORD] = support; > capbuf[OSC_CONTROL_DWORD] = *control | root->osc_control_set; > > - status = acpi_pci_run_osc(root->device->handle, capbuf, &result); > +retry: > + status = acpi_pci_run_osc(root, capbuf, &result); > if (ACPI_SUCCESS(status)) { > root->osc_support_set = support; > *control = result; > + } else if (is_cxl(root)) { > + /* > + * CXL _OSC is optional on CXL 1.1 hosts. Fall back to PCIe _OSC > + * upon any failure using CXL _OSC. > + */ > + root->cxl_osc_disable = true; > + goto retry; > } > return status; > } > @@ -338,7 +373,7 @@ static acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 s > u32 req = OSC_PCI_EXPRESS_CAPABILITY_CONTROL; > struct acpi_pci_root *root; > acpi_status status; > - u32 ctrl, capbuf[3]; > + u32 ctrl, capbuf[6]; > > if (!mask) > return AE_BAD_PARAMETER; > @@ -375,7 +410,7 @@ static acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 s > capbuf[OSC_QUERY_DWORD] = 0; > capbuf[OSC_SUPPORT_DWORD] = root->osc_support_set; > capbuf[OSC_CONTROL_DWORD] = ctrl; > - status = acpi_pci_run_osc(handle, capbuf, mask); > + status = acpi_pci_run_osc(root, capbuf, mask); > if (ACPI_FAILURE(status)) > return status; > > @@ -454,8 +489,7 @@ static bool os_control_query_checks(struct acpi_pci_root *root, u32 support) > return true; > } > > -static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm, > - bool is_pcie) > +static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm) > { > u32 support, control = 0, requested = 0; > acpi_status status; > @@ -506,7 +540,7 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm, > *no_aspm = 1; > > /* _OSC is optional for PCI host bridges */ > - if ((status == AE_NOT_FOUND) && !is_pcie) > + if ((status == AE_NOT_FOUND) && !is_pcie(root)) > return; > > if (control) { > @@ -529,7 +563,6 @@ static int acpi_pci_root_add(struct acpi_device *device, > acpi_handle handle = device->handle; > int no_aspm = 0; > bool hotadd = system_state == SYSTEM_RUNNING; > - bool is_pcie; > > root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL); > if (!root) > @@ -587,8 +620,7 @@ static int acpi_pci_root_add(struct acpi_device *device, > > root->mcfg_addr = acpi_pci_root_get_mcfg_addr(handle); > > - is_pcie = strcmp(acpi_device_hid(device), "PNP0A08") == 0; > - negotiate_os_control(root, &no_aspm, is_pcie); > + negotiate_os_control(root, &no_aspm); > > /* > * TBD: Need PCI interface for enumeration/configuration of roots. > -- > 2.35.1 >
