Hi,
On 9/6/2023 8:21 PM, Jason Andryuk wrote:
From: Roger Pau Monne roger.pau@citrix.com
The Processor _PDC buffer bits notify ACPI of the OS capabilities, and so ACPI can adjust the return of other Processor methods taking the OS capabilities into account.
_PDC method is deprecated for this purpose, since 2018, and is dropped from spec since 6.5
We made the switch in linux since 6.6: 95272641338a ("ACPI: processor: Use _OSC to convey OSPM processor support information")
When Linux is running as a Xen dom0, it's the hypervisor the entity in charge of processor power management, and hence Xen needs to make sure the capabilities reported in the _PDC buffer match the capabilities of the driver in Xen.
So I guess you would need to sanitize buffer passed to _OSC method instead ?
Introduce a small helper to sanitize the buffer when running as Xen dom0.
When Xen supports HWP, this serves as the equivalent of commit a21211672c9a ("ACPI / processor: Request native thermal interrupt handling via _OSC") to avoid SMM crashes. Xen will set bit 12 in the _PDC bits and the _PDC call will apply it.
[ jandryuk: Mention Xen HWP's need. Move local variables ] Signed-off-by: Roger Pau Monné roger.pau@citrix.com Cc: stable@vger.kernel.org Signed-off-by: Jason Andryuk jandryuk@gmail.com
v2: Move local variables in acpi_processor_eval_pdc() to reuse in both conditions.
arch/x86/include/asm/xen/hypervisor.h | 6 ++++++ arch/x86/xen/enlighten.c | 19 +++++++++++++++++++ drivers/acpi/processor_pdc.c | 22 ++++++++++++++++------ 3 files changed, 41 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/xen/hypervisor.h b/arch/x86/include/asm/xen/hypervisor.h index 5fc35f889cd1..0f88a7e450d3 100644 --- a/arch/x86/include/asm/xen/hypervisor.h +++ b/arch/x86/include/asm/xen/hypervisor.h @@ -63,4 +63,10 @@ void __init xen_pvh_init(struct boot_params *boot_params); void __init mem_map_via_hcall(struct boot_params *boot_params_p); #endif +#ifdef CONFIG_XEN_DOM0 +void xen_sanitize_pdc(uint32_t *buf); +#else +static inline void xen_sanitize_pdc(uint32_t *buf) { BUG(); } +#endif
#endif /* _ASM_X86_XEN_HYPERVISOR_H */ diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index b8db2148c07d..9f7fc11330a3 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -346,3 +346,22 @@ void xen_arch_unregister_cpu(int num) } EXPORT_SYMBOL(xen_arch_unregister_cpu); #endif
+#ifdef CONFIG_XEN_DOM0 +void xen_sanitize_pdc(uint32_t *buf) +{
- struct xen_platform_op op = {
.cmd = XENPF_set_processor_pminfo,.interface_version = XENPF_INTERFACE_VERSION,.u.set_pminfo.id = -1,.u.set_pminfo.type = XEN_PM_PDC,- };
- int ret;
- set_xen_guest_handle(op.u.set_pminfo.pdc, buf);
- ret = HYPERVISOR_platform_op(&op);
- if (ret)
pr_info("sanitize of _PDC buffer bits from Xen failed: %d\n",ret);+} +#endif diff --git a/drivers/acpi/processor_pdc.c b/drivers/acpi/processor_pdc.c index 18fb04523f93..9393dd4a3158 100644 --- a/drivers/acpi/processor_pdc.c +++ b/drivers/acpi/processor_pdc.c @@ -122,6 +122,11 @@ static acpi_status acpi_processor_eval_pdc(acpi_handle handle, struct acpi_object_list *pdc_in) { acpi_status status = AE_OK;
- union acpi_object *obj;
- u32 *buffer = NULL;
- obj = pdc_in->pointer;
- buffer = (u32 *)(obj->buffer.pointer);
if (boot_option_idle_override == IDLE_NOMWAIT) { /* @@ -129,14 +134,19 @@ acpi_processor_eval_pdc(acpi_handle handle, struct acpi_object_list *pdc_in) * mode will be disabled in the parameter of _PDC object. * Of course C1_FFH access mode will also be disabled. */
union acpi_object *obj;u32 *buffer = NULL;obj = pdc_in->pointer;buffer = (u32 *)(obj->buffer.pointer);- }
- if (xen_initial_domain()) {
/** When Linux is running as Xen dom0, the hypervisor is the* entity in charge of the processor power management, and so* Xen needs to check the OS capabilities reported in the _PDC* buffer matches what the hypervisor driver supports.*/xen_sanitize_pdc(buffer);- }
- status = acpi_evaluate_object(handle, "_PDC", pdc_in, NULL);
if (ACPI_FAILURE(status))