[Xen-devel] [RFC PATCH 18/33] Subarch support for CPUID instruction

[Chris Wright <chrisw@xxxxxxxxxxxx>]

Allow subarchitectures to modify the CPUID instruction.  This allows
the subarch to provide a limited set of CPUID feature flags during CPU
identification.  Add a subarch implementation for Xen that traps to the
hypervisor where unsupported feature flags can be hidden from guests.

Signed-off-by: Ian Pratt <ian.pratt@xxxxxxxxxxxxx>
Signed-off-by: Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
 arch/i386/kernel/head-cpu.S                    |    4 ++--
 include/asm-i386/mach-default/mach_processor.h |    7 +++++++
 include/asm-i386/mach-xen/mach_processor.h     |    9 +++++++++
 include/asm-i386/processor.h                   |   13 +++++++------
 4 files changed, 25 insertions(+), 8 deletions(-)

diff -r 122f3fbdb7a4 arch/i386/kernel/head-cpu.S
--- a/arch/i386/kernel/head-cpu.S       Thu Jun 22 20:30:11 2006 -0400
+++ b/arch/i386/kernel/head-cpu.S       Thu Jun 22 20:38:07 2006 -0400
@@ -1,4 +1,6 @@
 /* Some macros for head.S */
+
+#include <mach_processor.h>
 
 .macro CPU_GDT_TABLE
        .quad 0x0000000000000000        /* NULL descriptor */
@@ -57,7 +59,7 @@
 .macro CPUID_GET_VENDOR_INFO cpuid_level, x86_vendor_id
        /* get vendor info */
        xorl %eax,%eax                  # call CPUID with 0 -> return vendor ID
-       cpuid
+       CPUID
        movl %eax,\cpuid_level          # save CPUID level
        movl %ebx,\x86_vendor_id        # lo 4 chars
        movl %edx,\x86_vendor_id+4      # next 4 chars
@@ -73,7 +75,7 @@
  */
 .macro CPUID_GET_CPU_TYPE family, model, mask, capability
        movl $1,%eax            # Use the CPUID instruction to get CPU type
-       cpuid
+       CPUID
        movb %al,%cl            # save reg for future use
        andb $0x0f,%ah          # mask processor family
        movb %ah,\family
diff -r 122f3fbdb7a4 include/asm-i386/processor.h
--- a/include/asm-i386/processor.h      Thu Jun 22 20:30:11 2006 -0400
+++ b/include/asm-i386/processor.h      Thu Jun 22 20:38:07 2006 -0400
@@ -20,6 +20,7 @@
 #include <linux/threads.h>
 #include <asm/percpu.h>
 #include <linux/cpumask.h>
+#include <mach_processor.h>
 
 /* flag for disabling the tsc */
 extern int tsc_disable;
@@ -147,7 +148,7 @@ static inline void detect_ht(struct cpui
  */
 static inline void cpuid(unsigned int op, unsigned int *eax, unsigned int 
*ebx, unsigned int *ecx, unsigned int *edx)
 {
-       __asm__("cpuid"
+       __asm__(CPUID_STR
                : "=a" (*eax),
                  "=b" (*ebx),
                  "=c" (*ecx),
@@ -159,7 +160,7 @@ static inline void cpuid_count(int op, i
 static inline void cpuid_count(int op, int count, int *eax, int *ebx, int *ecx,
                int *edx)
 {
-       __asm__("cpuid"
+       __asm__(CPUID_STR
                : "=a" (*eax),
                  "=b" (*ebx),
                  "=c" (*ecx),
@@ -174,7 +175,7 @@ static inline unsigned int cpuid_eax(uns
 {
        unsigned int eax;
 
-       __asm__("cpuid"
+       __asm__(CPUID_STR
                : "=a" (eax)
                : "0" (op)
                : "bx", "cx", "dx");
@@ -184,7 +185,7 @@ static inline unsigned int cpuid_ebx(uns
 {
        unsigned int eax, ebx;
 
-       __asm__("cpuid"
+       __asm__(CPUID_STR
                : "=a" (eax), "=b" (ebx)
                : "0" (op)
                : "cx", "dx" );
@@ -194,7 +195,7 @@ static inline unsigned int cpuid_ecx(uns
 {
        unsigned int eax, ecx;
 
-       __asm__("cpuid"
+       __asm__(CPUID_STR
                : "=a" (eax), "=c" (ecx)
                : "0" (op)
                : "bx", "dx" );
@@ -204,7 +205,7 @@ static inline unsigned int cpuid_edx(uns
 {
        unsigned int eax, edx;
 
-       __asm__("cpuid"
+       __asm__(CPUID_STR
                : "=a" (eax), "=d" (edx)
                : "0" (op)
                : "bx", "cx");
diff -r 122f3fbdb7a4 include/asm-i386/mach-default/mach_processor.h
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-i386/mach-default/mach_processor.h    Thu Jun 22 20:38:07 
2006 -0400
@@ -0,0 +1,7 @@
+#ifndef __ASM_MACH_PROCESSOR_H
+#define __ASM_MACH_PROCESSOR_H
+
+#define CPUID cpuid
+#define CPUID_STR "cpuid"
+
+#endif /* __ASM_MACH_PROCESSOR_H */
diff -r 122f3fbdb7a4 include/asm-i386/mach-xen/mach_processor.h
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/include/asm-i386/mach-xen/mach_processor.h        Thu Jun 22 20:38:07 
2006 -0400
@@ -0,0 +1,9 @@
+#ifndef __ASM_MACH_PROCESSOR_H
+#define __ASM_MACH_PROCESSOR_H
+
+#include <xen/interface/arch-x86_32.h>
+
+#define CPUID XEN_CPUID
+#define CPUID_STR XEN_CPUID
+
+#endif /* __ASM_MACH_PROCESSOR_H */

--

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