[PATCH] mini-os: correct memory access rights for pvh mode

[Juergen Gross <jgross@xxxxxxxx>]

When running as a PVH guest the memory access rights are not set
correctly: _PAGE_USER should not be set and CR0.WP should be set.
Especially CR0.WP is important in order to let the allocate on
demand feature work, as it requires a page fault when writing to a
read-only page.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 arch/x86/x86_hvm.S    |  2 +-
 include/x86/arch_mm.h | 18 ++++++++++++------
 include/x86/os.h      |  1 +
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/arch/x86/x86_hvm.S b/arch/x86/x86_hvm.S
index 6e8ad98..42a5f02 100644
--- a/arch/x86/x86_hvm.S
+++ b/arch/x86/x86_hvm.S
@@ -20,7 +20,7 @@ _start:
 #endif /* __x86_64__ */
 
         mov %cr0, %eax
-        or $X86_CR0_PG, %eax
+        or $(X86_CR0_PG | X86_CR0_WP), %eax
         mov %eax, %cr0
 
         lgdt gdt_ptr
diff --git a/include/x86/arch_mm.h b/include/x86/arch_mm.h
index cbbeb21..ffbec5a 100644
--- a/include/x86/arch_mm.h
+++ b/include/x86/arch_mm.h
@@ -171,17 +171,23 @@ typedef unsigned long pgentry_t;
 #define _PAGE_PSE      CONST(0x080)
 #define _PAGE_GLOBAL   CONST(0x100)
 
+#ifdef CONFIG_PARAVIRT
+#define PAGE_USER _PAGE_USER
+#else
+#define PAGE_USER CONST(0)
+#endif
+
 #if defined(__i386__)
 #define L1_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED)
 #define L1_PROT_RO (_PAGE_PRESENT|_PAGE_ACCESSED)
-#define L2_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|_PAGE_DIRTY |_PAGE_USER)
+#define L2_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|_PAGE_DIRTY |PAGE_USER)
 #define L3_PROT (_PAGE_PRESENT)
 #elif defined(__x86_64__)
-#define L1_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|_PAGE_USER)
-#define L1_PROT_RO (_PAGE_PRESENT|_PAGE_ACCESSED|_PAGE_USER)
-#define L2_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|_PAGE_DIRTY|_PAGE_USER)
-#define L3_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|_PAGE_DIRTY|_PAGE_USER)
-#define L4_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|_PAGE_DIRTY|_PAGE_USER)
+#define L1_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|PAGE_USER)
+#define L1_PROT_RO (_PAGE_PRESENT|_PAGE_ACCESSED|PAGE_USER)
+#define L2_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|_PAGE_DIRTY|PAGE_USER)
+#define L3_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|_PAGE_DIRTY|PAGE_USER)
+#define L4_PROT (_PAGE_PRESENT|_PAGE_RW|_PAGE_ACCESSED|_PAGE_DIRTY|PAGE_USER)
 #endif /* __i386__ || __x86_64__ */
 
 /* flags for ioremap */
diff --git a/include/x86/os.h b/include/x86/os.h
index a73b63e..46a824d 100644
--- a/include/x86/os.h
+++ b/include/x86/os.h
@@ -27,6 +27,7 @@
 #define MSR_EFER          0xc0000080
 #define _EFER_LME         8             /* Long mode enable */
 
+#define X86_CR0_WP        0x00010000    /* Write protect */
 #define X86_CR0_PG        0x80000000    /* Paging */
 #define X86_CR4_PAE       0x00000020    /* enable physical address extensions 
*/
 #define X86_CR4_OSFXSR    0x00000200    /* enable fast FPU save and restore */
-- 
2.26.2