acpi/processor: sanitize _OSC/_PDC capabilities for Xen dom0

The Processor capability bits notify ACPI of the OS capabilities, and
so ACPI can adjust the return of other Processor methods taking the OS
capabilities into account.

When Linux is running as a Xen dom0, the hypervisor is the entity
in charge of processor power management, and hence Xen needs to make
sure the capabilities reported by _OSC/_PDC match the capabilities of
the driver in Xen.

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
ACPI_PROC_CAP_COLLAB_PROC_PERF (bit 12) in the capability bits and the
_OSC/_PDC call will apply it.

[ jandryuk: Mention Xen HWP's need.  Support _OSC & _PDC ]
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Michal Wilczynski <michal.wilczynski@intel.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20231108212517.72279-1-jandryuk@gmail.com
Signed-off-by: Juergen Gross <jgross@suse.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/x86/include/asm/xen/hypervisor.h b/arch/x86/include/asm/xen/hypervisor.h
index 7048dfacc04b..a9088250770f 100644
--- a/arch/x86/include/asm/xen/hypervisor.h
+++ b/arch/x86/include/asm/xen/hypervisor.h
@@ -100,4 +100,13 @@ static inline void leave_lazy(enum xen_lazy_mode mode)
 
 enum xen_lazy_mode xen_get_lazy_mode(void);
 
+#if defined(CONFIG_XEN_DOM0) && defined(CONFIG_ACPI)
+void xen_sanitize_proc_cap_bits(uint32_t *buf);
+#else
+static inline void xen_sanitize_proc_cap_bits(uint32_t *buf)
+{
+	BUG();
+}
+#endif
+
 #endif /* _ASM_X86_XEN_HYPERVISOR_H */