[Xen-devel] [PATCH 26 of 38] xen: forcibly disable PAT support

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

From: Ian Campbell <ian.campbell@xxxxxxxxxx>

Xen imposes a particular PAT layout on all paravirtual guests which
does not match the layout Linux would like to use.

Force PAT to be disabled until this is resolved.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 arch/x86/include/asm/pat.h |    4 ++--
 arch/x86/xen/enlighten.c   |    3 +++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/pat.h b/arch/x86/include/asm/pat.h
--- a/arch/x86/include/asm/pat.h
+++ b/arch/x86/include/asm/pat.h
@@ -6,9 +6,11 @@
 #ifdef CONFIG_X86_PAT
 extern int pat_enabled;
 extern void validate_pat_support(struct cpuinfo_x86 *c);
+extern void pat_disable(char *reason);
 #else
 static const int pat_enabled;
 static inline void validate_pat_support(struct cpuinfo_x86 *c) { }
+static inline void pat_disable(char *reason) { }
 #endif
 
 extern void pat_init(void);
@@ -17,6 +19,4 @@
                unsigned long req_type, unsigned long *ret_type);
 extern int free_memtype(u64 start, u64 end);
 
-extern void pat_disable(char *reason);
-
 #endif /* _ASM_X86_PAT_H */
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -48,6 +48,7 @@
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 #include <asm/reboot.h>
+#include <asm/pat.h>
 
 #include "xen-ops.h"
 #include "mmu.h"
@@ -1743,6 +1744,8 @@
                add_preferred_console("hvc", 0, NULL);
        }
 
+       pat_disable("PAT disabled on Xen");
+
        xen_raw_console_write("about to get started...\n");
 
        /* Start the world */



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