KVM: Portability: Move memory segmentation to x86.c

This patch moves the definition of segment_descriptor_64 for AMD64 and
EM64T from kvm_main.c to segment_descriptor.h. It also adds a proper
#ifndef...#define...#endif around that header file.
The implementation of segment_base is moved from kvm_main.c to x86.c.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/drivers/kvm/x86.c b/drivers/kvm/x86.c
index b84cb6707f78..5a959220410a 100644
--- a/drivers/kvm/x86.c
+++ b/drivers/kvm/x86.c
@@ -16,16 +16,49 @@
 
 #include "kvm.h"
 #include "x86.h"
+#include "segment_descriptor.h"
 #include "irq.h"
 
 #include <linux/kvm.h>
 #include <linux/fs.h>
 #include <linux/vmalloc.h>
+#include <linux/module.h>
 
 #include <asm/uaccess.h>
 
 #define MAX_IO_MSRS 256
 
+unsigned long segment_base(u16 selector)
+{
+	struct descriptor_table gdt;
+	struct segment_descriptor *d;
+	unsigned long table_base;
+	unsigned long v;
+
+	if (selector == 0)
+		return 0;
+
+	asm("sgdt %0" : "=m"(gdt));
+	table_base = gdt.base;
+
+	if (selector & 4) {           /* from ldt */
+		u16 ldt_selector;
+
+		asm("sldt %0" : "=g"(ldt_selector));
+		table_base = segment_base(ldt_selector);
+	}
+	d = (struct segment_descriptor *)(table_base + (selector & ~7));
+	v = d->base_low | ((unsigned long)d->base_mid << 16) |
+		((unsigned long)d->base_high << 24);
+#ifdef CONFIG_X86_64
+	if (d->system == 0 && (d->type == 2 || d->type == 9 || d->type == 11))
+		v |= ((unsigned long) \
+		      ((struct segment_descriptor_64 *)d)->base_higher) << 32;
+#endif
+	return v;
+}
+EXPORT_SYMBOL_GPL(segment_base);
+
 /*
  * List of msr numbers which we expose to userspace through KVM_GET_MSRS
  * and KVM_SET_MSRS, and KVM_GET_MSR_INDEX_LIST.