x86/platform/uv: Provide is_early_uv_system()

Introduce is_early_uv_system() which uses efi.uv_systab to decide early
in the boot process whether the kernel runs on a UV system.

This is needed to skip other early setup/init code that might break
the UV platform if done too early such as before necessary ACPI tables
parsing takes place.

Suggested-by: Hedi Berriche <[email protected]>
Signed-off-by: Mike Travis <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Russ Anderson <[email protected]>
Reviewed-by: Dimitri Sivanich <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Russ Anderson <[email protected]>
Cc: Dimitri Sivanich <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Kate Stewart <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Philippe Ombredanne <[email protected]>
Cc: Pavel Tatashin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Len Brown <[email protected]>
Cc: Dou Liyang <[email protected]>
Cc: Xiaoming Gao <[email protected]>
Cc: Rajvi Jingar <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/x86/include/asm/uv/uv.h b/arch/x86/include/asm/uv/uv.h
index a80c0673798f..e60c45fd3679 100644
--- a/arch/x86/include/asm/uv/uv.h
+++ b/arch/x86/include/asm/uv/uv.h
@@ -10,8 +10,13 @@ struct cpumask;
 struct mm_struct;
 
 #ifdef CONFIG_X86_UV
+#include <linux/efi.h>
 
 extern enum uv_system_type get_uv_system_type(void);
+static inline bool is_early_uv_system(void)
+{
+	return !((efi.uv_systab == EFI_INVALID_TABLE_ADDR) || !efi.uv_systab);
+}
 extern int is_uv_system(void);
 extern int is_uv_hubless(void);
 extern void uv_cpu_init(void);
@@ -23,6 +28,7 @@ extern const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask,
 #else	/* X86_UV */
 
 static inline enum uv_system_type get_uv_system_type(void) { return UV_NONE; }
+static inline bool is_early_uv_system(void)	{ return 0; }
 static inline int is_uv_system(void)	{ return 0; }
 static inline int is_uv_hubless(void)	{ return 0; }
 static inline void uv_cpu_init(void)	{ }