[RFC PATCH 8/8] Use Linux's PAT

[Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>]

This is purely for testing, to see if it works around a bug in i915.  It
is not intended to be merged.

NOT-signed-off-by: DO NOT MERGE
---
 xen/arch/x86/include/asm/page.h      |  4 ++--
 xen/arch/x86/include/asm/processor.h | 12 ++++++------
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/include/asm/page.h b/xen/arch/x86/include/asm/page.h
index 
b585235d064a567082582c8e92a4e8283fd949ca..ab9b46f1d0901e50a83fd035ff28d1bda0b781a2
 100644
--- a/xen/arch/x86/include/asm/page.h
+++ b/xen/arch/x86/include/asm/page.h
@@ -333,11 +333,11 @@ void efi_update_l4_pgtable(unsigned int l4idx, 
l4_pgentry_t);
 
 /* Memory types, encoded under Xen's choice of MSR_PAT. */
 #define _PAGE_WB         (                                0)
-#define _PAGE_WT         (                        _PAGE_PWT)
+#define _PAGE_WC         (                        _PAGE_PWT)
 #define _PAGE_UCM        (            _PAGE_PCD            )
 #define _PAGE_UC         (            _PAGE_PCD | _PAGE_PWT)
-#define _PAGE_WC         (_PAGE_PAT                        )
 #define _PAGE_WP         (_PAGE_PAT |             _PAGE_PWT)
+#define _PAGE_WT         (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT)
 
 /*
  * Debug option: Ensure that granted mappings are not implicitly unmapped.
diff --git a/xen/arch/x86/include/asm/processor.h 
b/xen/arch/x86/include/asm/processor.h
index 
64b75e444947c64e2e5eba457deec92a873d7a63..7a27d19d1dc8aa9c102683985c30fb85864303fa
 100644
--- a/xen/arch/x86/include/asm/processor.h
+++ b/xen/arch/x86/include/asm/processor.h
@@ -107,18 +107,18 @@
  * MSR_PAT value, and is an ABI with PV guests.
  */
 #define XEN_MSR_PAT (MSR_PAT_WB  << 0x00 | \
-                     MSR_PAT_WT  << 0x08 | \
+                     MSR_PAT_WC  << 0x08 | \
                      MSR_PAT_UCM << 0x10 | \
                      MSR_PAT_UC  << 0x18 | \
-                     MSR_PAT_WC  << 0x20 | \
+                     MSR_PAT_WB  << 0x20 | \
                      MSR_PAT_WP  << 0x28 | \
-                     MSR_PAT_UC  << 0x30 | \
-                     MSR_PAT_UC  << 0x38 | \
+                     MSR_PAT_UCM << 0x30 | \
+                     MSR_PAT_WT  << 0x38 | \
                      0)
 
 #ifndef __ASSEMBLY__
-_Static_assert(XEN_MSR_PAT == 0x050100070406ULL,
-               "wrong XEN_MSR_PAT breaks PV guests");
+_Static_assert(XEN_MSR_PAT == 0x0407050600070106ULL,
+               "wrong XEN_MSR_PAT breaks i915 driver on PV Linux");
 
 struct domain;
 struct vcpu;
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab