[PATCH] x86/cstate: Allow ACPI C1 FFH MWAIT use on Hygon systems

[Pu Wen]

Hygon systems support the Monitor/Mwait instructions and these can be used
for ACPI C1 in the same way as on AMD and Intel systems.

The BIOS declares a C1 state in _CST to use FFH and CPUID_Fn00000005_EDX
is non-zero on Hygon systems.

Allow ffh_cstate_init() to succeed on Hygon systems to default using FFH
MWAIT instead of HALT for ACPI C1.

Tested successfully on Hygon Fam18h systems.

Signed-off-by: Pu Wen <puwen@xxxxxxxx>
---
 arch/x86/kernel/acpi/cstate.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index 49ae4e1ac9cd..7de599eba7f0 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -197,7 +197,8 @@ static int __init ffh_cstate_init(void)
 	struct cpuinfo_x86 *c = &boot_cpu_data;
 
 	if (c->x86_vendor != X86_VENDOR_INTEL &&
-	    c->x86_vendor != X86_VENDOR_AMD)
+	    c->x86_vendor != X86_VENDOR_AMD &&
+	    c->x86_vendor != X86_VENDOR_HYGON)
 		return -1;
 
 	cpu_cstate_entry = alloc_percpu(struct cstate_entry);
-- 
2.23.0