[PATCH] drm/ttm: provide default page protection for UML

[Randy Dunlap]

boot_cpu_data [struct cpuinfo_um (on UML)] does not have a struct
member named 'x86', so provide a default page protection mode
for CONFIG_UML.

Mends this build error:
../drivers/gpu/drm/ttm/ttm_module.c: In function ‘ttm_prot_from_caching’:
../drivers/gpu/drm/ttm/ttm_module.c:59:24: error: ‘struct cpuinfo_um’ has no member named ‘x86’
  else if (boot_cpu_data.x86 > 3)
                        ^

Fixes: 3bf3710e3718 ("drm/ttm: Add a generic TTM memcpy move for page-based iomem")
Signed-off-by: Randy Dunlap <rdunlap at infradead.org>
Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Cc: Christian König <christian.koenig at amd.com>
Cc: Huang Rui <ray.huang at amd.com>
Cc: dri-devel at lists.freedesktop.org
Cc: Jeff Dike <jdike at addtoit.com>
Cc: Richard Weinberger <richard at nod.at>
Cc: Anton Ivanov <anton.ivanov at cambridgegreys.com>
Cc: linux-um at lists.infradead.org
Cc: David Airlie <airlied at linux.ie>
Cc: Daniel Vetter <daniel at ffwll.ch>
---
 drivers/gpu/drm/ttm/ttm_module.c |    4 ++++
 1 file changed, 4 insertions(+)

--- linux-next-20210901.orig/drivers/gpu/drm/ttm/ttm_module.c
+++ linux-next-20210901/drivers/gpu/drm/ttm/ttm_module.c
@@ -53,6 +53,9 @@ pgprot_t ttm_prot_from_caching(enum ttm_
 	if (caching == ttm_cached)
 		return tmp;
 
+#ifdef CONFIG_UML
+	tmp = pgprot_noncached(tmp);
+#else
 #if defined(__i386__) || defined(__x86_64__)
 	if (caching == ttm_write_combined)
 		tmp = pgprot_writecombine(tmp);
@@ -69,6 +72,7 @@ pgprot_t ttm_prot_from_caching(enum ttm_
 #if defined(__sparc__)
 	tmp = pgprot_noncached(tmp);
 #endif
+#endif
 	return tmp;
 }