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Subject[RFC PATCH 14/35] subarch modify CPU capabilities
Allow subarchitectures to modify CPU capabilities during bootstrap CPU
identification. Add a subarch implementation for Xen which hides
features unsupported by the hypervisor.

Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
arch/i386/kernel/cpu/common.c | 3 +++
include/asm-i386/mach-default/mach_cpu.h | 5 +++++
include/asm-i386/mach-xen/mach_cpu.h | 2 ++
include/asm-i386/mach-xen/setup_arch_post.h | 15 +++++++++++++++
include/asm-i386/mach-xen/setup_arch_pre.h | 1 +
5 files changed, 26 insertions(+)

--- xen-subarch-2.6.orig/arch/i386/kernel/cpu/common.c
+++ xen-subarch-2.6/arch/i386/kernel/cpu/common.c
@@ -16,6 +16,7 @@
#include <asm/apic.h>
#include <mach_apic.h>
#endif
+#include <mach_cpu.h>

#include "cpu.h"

@@ -420,6 +421,8 @@ void __devinit identify_cpu(struct cpuin
c->x86_vendor, c->x86_model);
}

+ machine_specific_modify_cpu_capabilities(c);
+
/* Now the feature flags better reflect actual CPU features! */

printk(KERN_DEBUG "CPU: After all inits, caps:");
--- xen-subarch-2.6.orig/include/asm-i386/mach-xen/setup_arch_post.h
+++ xen-subarch-2.6/include/asm-i386/mach-xen/setup_arch_post.h
@@ -18,6 +18,19 @@ static char * __init machine_specific_me
return "Xen";
}

+void __devinit machine_specific_modify_cpu_capabilities(struct cpuinfo_x86 *c)
+{
+ clear_bit(X86_FEATURE_VME, c->x86_capability);
+ clear_bit(X86_FEATURE_DE, c->x86_capability);
+ clear_bit(X86_FEATURE_PSE, c->x86_capability);
+ clear_bit(X86_FEATURE_PGE, c->x86_capability);
+ clear_bit(X86_FEATURE_SEP, c->x86_capability);
+ clear_bit(X86_FEATURE_MWAIT, c->x86_capability);
+ if (!(xen_start_info->flags & SIF_PRIVILEGED))
+ clear_bit(X86_FEATURE_MTRR, c->x86_capability);
+ c->hlt_works_ok = 0;
+}
+
static void __init machine_specific_arch_setup(void)
{
struct physdev_op op;
@@ -30,6 +43,8 @@ static void __init machine_specific_arch
__KERNEL_CS, (unsigned long)hypervisor_callback,
__KERNEL_CS, (unsigned long)failsafe_callback);

+ machine_specific_modify_cpu_capabilities(&boot_cpu_data);
+
init_pg_tables_end = __pa(xen_start_info->pt_base) +
PFN_PHYS(xen_start_info->nr_pt_frames);

--- xen-subarch-2.6.orig/include/asm-i386/mach-xen/setup_arch_pre.h
+++ xen-subarch-2.6/include/asm-i386/mach-xen/setup_arch_pre.h
@@ -1,6 +1,7 @@

#include <xen/interface/xen.h>
#include <asm/hypervisor.h>
+#include <mach_cpu.h>

struct start_info *xen_start_info;
EXPORT_SYMBOL(xen_start_info);
--- /dev/null
+++ xen-subarch-2.6/include/asm-i386/mach-default/mach_cpu.h
@@ -0,0 +1,5 @@
+
+static inline void
+machine_specific_modify_cpu_capabilities(struct cpuinfo_x86 *c)
+{
+}
--- /dev/null
+++ xen-subarch-2.6/include/asm-i386/mach-xen/mach_cpu.h
@@ -0,0 +1,2 @@
+
+extern void machine_specific_modify_cpu_capabilities(struct cpuinfo_x86 *);
--
-
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