Changeset 67112 in vbox for trunk/src

Timestamp:

May 26, 2017 11:34:08 AM (8 years ago)

Author:

vboxsync

Message:

BIOS: Check APIC availability before hitting the APIC base MSR.

Location:

trunk/src/VBox/Devices/PC/BIOS

Files:

• inlines.h (modified) (3 diffs)
• post.c (modified) (4 diffs)

trunk/src/VBox/Devices/PC/BIOS/inlines.h

@@ -4 +4 @@
 
 /*
- * Copyright (C) 2010-2016 Oracle Corporation
+ * Copyright (C) 2010-2017 Oracle Corporation
  *
  * This file is part of VirtualBox Open Source Edition (OSE), as
@@ -146 +146 @@
 #if VBOX_BIOS_CPU >= 80386
 
-/* Warning: msr_read/msr_write destroy high bits of 32-bit registers. */
+/* Warning: msr_read/msr_write destroy high bits of 32-bit registers (EAX, ECX, EDX). */
 
 uint64_t msr_read(uint32_t msr);
@@ -177 +177 @@
     parm [ax bx cx dx] [di si] modify [] nomemory;
 
+/* Warning: eflags_read/eflags_write destroy high bits of 32-bit registers (EDX). */
+uint32_t eflags_read( void );
+#pragma aux eflags_read =   \
+    ".386"                  \
+    "pushfd"                \
+    "pop  edx"              \
+    "mov  ax, dx"           \
+    "shr  edx, 16"          \
+    value [dx ax] modify [dx ax];
+
+uint32_t eflags_write( uint32_t e_flags );
+#pragma aux eflags_write =  \
+    ".386"                  \
+    "shl  edx, 16"          \
+    "mov  dx, ax"           \
+    "push edx"              \
+    "popfd"                 \
+    parm [dx ax] modify [dx ax];
+
+/* Warning cpuid destroys high bits of 32-bit registers (EAX, EBX, ECX, EDX). */
+void cpuid( uint32_t __far cpu_id[4], uint32_t leaf );
+#pragma aux cpuid =         \
+    ".586"                  \
+    "shl  edx, 16"          \
+    "mov  dx, ax"           \
+    "mov  eax, edx"         \
+    "cpuid"                 \
+    "mov  es:[di+0], eax"   \
+    "mov  es:[di+4], ebx"   \
+    "mov  es:[di+8], ecx"   \
+    "mov  es:[di+12], edx"  \
+    parm [es di] [dx ax] modify [bx cx dx]
+
 #endif

trunk/src/VBox/Devices/PC/BIOS/post.c

@@ -4 +4 @@
 
 /*
- * Copyright (C) 2004-2016 Oracle Corporation
+ * Copyright (C) 2004-2017 Oracle Corporation
  *
  * This file is part of VirtualBox Open Source Edition (OSE), as
@@ -104 +104 @@
 #if VBOX_BIOS_CPU >= 80386
 
+/* NB: The CPUID detection is generic but currently not used elsewhere. */
+
+/* Check CPUID availability. */
+int is_cpuid_supported( void )
+{
+    uint32_t    old_flags, new_flags;
+
+    old_flags = eflags_read();
+    new_flags = old_flags ^ (1L << 21); /* Toggle CPUID bit. */
+    eflags_write( new_flags );
+    new_flags = eflags_read();
+    return( old_flags != new_flags );   /* Supported if bit changed. */
+}
+
 #define APICMODE_DISABLED   0
 #define APICMODE_APIC       1
@@ -121 +135 @@
  * existing virtual wire setup.
  *
- * NB: This code assumes that there *is* a local APIC.
+ * NB: This code does not assume that there is a local APIC. It is necessary
+ * to check CPUID whether APIC is present; the CPUID instruction might not be
+ * available either.
  *
  * NB: Destroys high bits of 32-bit registers.
@@ -130 +146 @@
     uint16_t    mask;
     uint8_t     apic_mode;
+    uint32_t    cpu_id[4];
+
+    /* If there's no CPUID, there's certainly no APIC. */
+    if (!is_cpuid_supported()) {
+        return;
+    }
+
+    /* Check EDX bit 9 */
+    cpuid(&cpu_id, 1);
+    BX_DEBUG("CPUID EDX: 0x%lx\n", cpu_id[3]);
+    if ((cpu_id[3] & (1 << 9)) == 0) {
+        return; /* No local APIC, nothing to do. */
+    }
 
     /* APIC mode at offset 78h in CMOS NVRAM. */