| Message ID | 20220225055224.190669-3-mario.limonciello@amd.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2,1/3] ACPI: APEI: Adjust for acpi_run_osc logic changes | expand |
On Thu, Feb 24, 2022 at 11:52:24PM -0600, Mario Limonciello wrote: > According to the ACPI 6.4 spec: > It is strongly recommended that the OS evaluate _OSC with the Query > Support Flag set until _OSC returns the Capabilities Masked bit clear, > to negotiate the set of features to be granted to the OS for native > support; a platform may require a specific combination of features > to be supported natively by an OS before granting native control > of a given feature. After negotiation with the query flag set, > the OS should evaluate without it so that any negotiated values > can be made effective to hardware. > > Currently the code sends the exact same values in both executions of the > OSC and this leads to some problems on some AMD platforms in certain _OSC > configurations. > > The following notable capabilities are set by OSPM when query is enabled: > * OSC_SB_PR3_SUPPORT > * OSC_SB_PCLPI_SUPPORT > * OSC_SB_NATIVE_USB4_SUPPORT > > The first call to the platform OSC returns back a masked capabilities > error because the firmware did not acknolwedge OSC_SB_PCLPI_SUPPORT but acknowledge > it acknolwedged the others. > > The second call to the platform OSC without the query flag set then _OSC > fails because the OSPM still sent the exact same values. This leads > to not acknowledging OSC_SB_NATIVE_USB4_SUPPORT and later USB4 PCIe > tunnels can't be authorized. > > This problem was first introduced by commit 159d8c274fd9 ("ACPI: Pass the > same capabilities to the _OSC regardless of the query flag") which subtly > adjusted the behavior from 719e1f5 ("ACPI: Execute platform _OSC also > with query bit clear"). > > The OSC was called exactly 2 times: > * Once to query and request from firmware > * Once to commit to firmware without query > > To fix this problem, continue to call the OSC until the firmware has _OSC > indicated that capabilities are no longer masked or after an arbitrary > number of negotiation attempts. > > Furthermore, to avoid the problem that commit 159d8c274fd9 ("ACPI: Pass > the same capabilities to the _OSC regardless of the query flag") > introduced, explicitly mark support for CPC and CPPCv2 even if they > were masked by the series of query calls due to table loading order on > some systems. > > Fixes: 159d8c274fd9 ("ACPI: Pass the same capabilities to the _OSC regardless of the query flag") > Signed-off-by: Mario Limonciello <mario.limonciello@amd.com> > --- > changes from v1->v2: > * Fix a NULL pointer dereference caught by 0day CI > drivers/acpi/bus.c | 30 ++++++++++++++++++++++++++++-- > 1 file changed, 28 insertions(+), 2 deletions(-) > > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c > index f0f9e0934c10..489cc4f6b6e6 100644 > --- a/drivers/acpi/bus.c > +++ b/drivers/acpi/bus.c > @@ -297,6 +297,8 @@ static void acpi_bus_osc_negotiate_platform_control(void) > .cap.pointer = capbuf, > }; > acpi_handle handle; > + acpi_status status; > + int i; > > capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE; > capbuf[OSC_SUPPORT_DWORD] = OSC_SB_PR3_SUPPORT; /* _PR3 is in use */ > @@ -332,10 +334,34 @@ static void acpi_bus_osc_negotiate_platform_control(void) > if (ACPI_FAILURE(acpi_get_handle(NULL, "\\_SB", &handle))) > return; > > - if (ACPI_FAILURE(acpi_run_osc(handle, &context))) > + /* > + * check if bits were masked, we need to negotiate > + * prevent potential endless loop by limited number of > + * negotiation cycles Start with capital letter and end with '.' a multiline comment. /* * Check if ... * ... * negotiation cycles. */ > + */ > + for (i = 0; i < 5; i++) { > + status = acpi_run_osc(handle, &context); > + if (ACPI_SUCCESS(status) || status == AE_SUPPORT) { > + capbuf_ret = context.ret.pointer; > + capbuf[OSC_SUPPORT_DWORD] = capbuf_ret[OSC_SUPPORT_DWORD]; > + kfree(context.ret.pointer); I wonder if it makes sense to document the acpi_run_osc() to tell in which return codes you actually need to kfree() the result. Here it is hard to tell IMHO. > + } > + if (status != AE_SUPPORT) > + break; > + } > + if (ACPI_FAILURE(status)) > return; > > - kfree(context.ret.pointer); > + /* > + * avoid problems with BIOS dynamically loading tables by indicating > + * support for CPPC even if it was masked Ditto for the comment. > + */ > +#ifdef CONFIG_X86 > + if (boot_cpu_has(X86_FEATURE_HWP)) { > + capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_CPC_SUPPORT; > + capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_CPCV2_SUPPORT; > + } > +#endif > > /* Now run _OSC again with query flag clear */ > capbuf[OSC_QUERY_DWORD] = 0; > -- > 2.34.1
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c index f0f9e0934c10..489cc4f6b6e6 100644 --- a/drivers/acpi/bus.c +++ b/drivers/acpi/bus.c @@ -297,6 +297,8 @@ static void acpi_bus_osc_negotiate_platform_control(void) .cap.pointer = capbuf, }; acpi_handle handle; + acpi_status status; + int i; capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE; capbuf[OSC_SUPPORT_DWORD] = OSC_SB_PR3_SUPPORT; /* _PR3 is in use */ @@ -332,10 +334,34 @@ static void acpi_bus_osc_negotiate_platform_control(void) if (ACPI_FAILURE(acpi_get_handle(NULL, "\\_SB", &handle))) return; - if (ACPI_FAILURE(acpi_run_osc(handle, &context))) + /* + * check if bits were masked, we need to negotiate + * prevent potential endless loop by limited number of + * negotiation cycles + */ + for (i = 0; i < 5; i++) { + status = acpi_run_osc(handle, &context); + if (ACPI_SUCCESS(status) || status == AE_SUPPORT) { + capbuf_ret = context.ret.pointer; + capbuf[OSC_SUPPORT_DWORD] = capbuf_ret[OSC_SUPPORT_DWORD]; + kfree(context.ret.pointer); + } + if (status != AE_SUPPORT) + break; + } + if (ACPI_FAILURE(status)) return; - kfree(context.ret.pointer); + /* + * avoid problems with BIOS dynamically loading tables by indicating + * support for CPPC even if it was masked + */ +#ifdef CONFIG_X86 + if (boot_cpu_has(X86_FEATURE_HWP)) { + capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_CPC_SUPPORT; + capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_CPCV2_SUPPORT; + } +#endif /* Now run _OSC again with query flag clear */ capbuf[OSC_QUERY_DWORD] = 0;
According to the ACPI 6.4 spec: It is strongly recommended that the OS evaluate _OSC with the Query Support Flag set until _OSC returns the Capabilities Masked bit clear, to negotiate the set of features to be granted to the OS for native support; a platform may require a specific combination of features to be supported natively by an OS before granting native control of a given feature. After negotiation with the query flag set, the OS should evaluate without it so that any negotiated values can be made effective to hardware. Currently the code sends the exact same values in both executions of the OSC and this leads to some problems on some AMD platforms in certain configurations. The following notable capabilities are set by OSPM when query is enabled: * OSC_SB_PR3_SUPPORT * OSC_SB_PCLPI_SUPPORT * OSC_SB_NATIVE_USB4_SUPPORT The first call to the platform OSC returns back a masked capabilities error because the firmware did not acknolwedge OSC_SB_PCLPI_SUPPORT but it acknolwedged the others. The second call to the platform OSC without the query flag set then fails because the OSPM still sent the exact same values. This leads to not acknowledging OSC_SB_NATIVE_USB4_SUPPORT and later USB4 PCIe tunnels can't be authorized. This problem was first introduced by commit 159d8c274fd9 ("ACPI: Pass the same capabilities to the _OSC regardless of the query flag") which subtly adjusted the behavior from 719e1f5 ("ACPI: Execute platform _OSC also with query bit clear"). The OSC was called exactly 2 times: * Once to query and request from firmware * Once to commit to firmware without query To fix this problem, continue to call the OSC until the firmware has indicated that capabilities are no longer masked or after an arbitrary number of negotiation attempts. Furthermore, to avoid the problem that commit 159d8c274fd9 ("ACPI: Pass the same capabilities to the _OSC regardless of the query flag") introduced, explicitly mark support for CPC and CPPCv2 even if they were masked by the series of query calls due to table loading order on some systems. Fixes: 159d8c274fd9 ("ACPI: Pass the same capabilities to the _OSC regardless of the query flag") Signed-off-by: Mario Limonciello <mario.limonciello@amd.com> --- changes from v1->v2: * Fix a NULL pointer dereference caught by 0day CI drivers/acpi/bus.c | 30 ++++++++++++++++++++++++++++-- 1 file changed, 28 insertions(+), 2 deletions(-)