inmates: x86: Enable MTRRs during start to avoid disable caches

Since fe8fac80d7, emulation of the MTRR enable bit works. That has no
effect on KVM so far, but we effectively run with hand break put on over
real hardware.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

diff --git a/inmates/lib/x86/header-32.S b/inmates/lib/x86/header-32.S
index 7487c8ae17283b7dbc5e5fd20130476a0b45fce7..952619e85a00a8d1ea844e67e04995a0e745ea2e 100644 (file)
--- a/inmates/lib/x86/header-32.S
+++ b/inmates/lib/x86/header-32.S
@@ -12,11 +12,14 @@
 
 #include <inmate.h>
 
-#define X86_CR0_PE     0x00000001
-#define X86_CR0_WP     0x00010000
-#define X86_CR0_PG     0x80000000
+#define X86_CR0_PE             0x00000001
+#define X86_CR0_WP             0x00010000
+#define X86_CR0_PG             0x80000000
 
-#define X86_CR4_PSE    0x00000010
+#define X86_CR4_PSE            0x00000010
+
+#define MSR_MTRR_DEF_TYPE      0x000002ff
+#define MTRR_ENABLE            0x00000800
 
        .code16
        .section ".boot", "ax"
@@ -48,6 +51,11 @@ start32:
        mov $(X86_CR0_PG | X86_CR0_WP | X86_CR0_PE),%eax
        mov %eax,%cr0
 
+       movl $MSR_MTRR_DEF_TYPE,%ecx
+       rdmsr
+       or $MTRR_ENABLE,%eax
+       wrmsr
+
        mov $stack_top,%esp
 
        mov $INMATE_DS32,%eax

diff --git a/inmates/lib/x86/header.S b/inmates/lib/x86/header.S
index adfce6e9c7a7e1434c5c5e844ad75dc691a1eae6..6eb8e497030d215867d7fafd8bad131a505eef5a 100644 (file)
--- a/inmates/lib/x86/header.S
+++ b/inmates/lib/x86/header.S
@@ -12,14 +12,17 @@
 
 #include <inmate.h>
 
-#define X86_CR0_PE     0x00000001
-#define X86_CR0_WP     0x00010000
-#define X86_CR0_PG     0x80000000
+#define X86_CR0_PE             0x00000001
+#define X86_CR0_WP             0x00010000
+#define X86_CR0_PG             0x80000000
 
-#define X86_CR4_PAE    0x00000020
+#define X86_CR4_PAE            0x00000020
 
-#define MSR_EFER       0xc0000080
-#define EFER_LME       0x00000100
+#define MSR_EFER               0xc0000080
+#define EFER_LME               0x00000100
+
+#define MSR_MTRR_DEF_TYPE      0x000002ff
+#define MTRR_ENABLE            0x00000800
 
        .code16
        .section ".boot", "ax"
@@ -48,6 +51,11 @@ start32:
        mov $pml4 + FSEGMENT_BASE,%eax
        mov %eax,%cr3
 
+       movl $MSR_MTRR_DEF_TYPE,%ecx
+       rdmsr
+       or $MTRR_ENABLE,%eax
+       wrmsr
+
        movl $MSR_EFER,%ecx
        rdmsr
        or $EFER_LME,%eax