From b5bb71e4224f44ad1059ad95f7e4eb651869684c Mon Sep 17 00:00:00 2001
From: Stephen Tweedie <sct@redhat.com>
Date: Mon, 10 Dec 2007 11:32:15 +0000
Subject: [PATCH] xen mtrr: Add mtrr_ops support for Xen mtrr

Add a Xen mtrr type, and reorganise mtrr initialisation slightly to allow the
mtrr driver to set up num_var_ranges (Xen needs to do this by querying the
hypervisor itself.)

Only the boot path is handled for now: we set up a xen-specific mtrr_if
and set up the mtrr tables based on hypervisor information, but we don't
yet handle mtrr entry add/delete.

Signed-off-by: Stephen Tweedie <sct@redhat.com>
---
 arch/x86/kernel/cpu/mtrr/Makefile |    1 +
 arch/x86/kernel/cpu/mtrr/main.c   |   30 ++++++++++++++++---
 arch/x86/kernel/cpu/mtrr/xen.c    |   57 +++++++++++++++++++++++++++++++++++++
 3 files changed, 83 insertions(+), 5 deletions(-)
 create mode 100644 arch/x86/kernel/cpu/mtrr/xen.c

diff --git a/arch/x86/kernel/cpu/mtrr/Makefile b/arch/x86/kernel/cpu/mtrr/Makefile
index 191fc05..81db513 100644
--- a/arch/x86/kernel/cpu/mtrr/Makefile
+++ b/arch/x86/kernel/cpu/mtrr/Makefile
@@ -1,3 +1,4 @@
 obj-y		:= main.o if.o generic.o state.o
 obj-$(CONFIG_X86_32) += amd.o cyrix.o centaur.o
+obj-$(CONFIG_XEN) += xen.o
 
diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index 3b20613..4fa6ecd 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -572,6 +572,7 @@ EXPORT_SYMBOL(mtrr_del);
 extern void amd_init_mtrr(void);
 extern void cyrix_init_mtrr(void);
 extern void centaur_init_mtrr(void);
+extern void xen_init_mtrr(void);
 
 static void __init init_ifs(void)
 {
@@ -580,6 +581,9 @@ static void __init init_ifs(void)
 	cyrix_init_mtrr();
 	centaur_init_mtrr();
 #endif
+#ifdef CONFIG_XEN
+	xen_init_mtrr();
+#endif
 }
 
 /* The suspend/resume methods are only for CPU without MTRR. CPU using generic
@@ -635,16 +639,14 @@ static struct sysdev_driver mtrr_sysdev_driver = {
 
 
 /**
- * mtrr_bp_init - initialize mtrrs on the boot CPU
+ * mtrr_bp_detect - detect mtrr hardware on the boot CPU
  *
  * This needs to be called early; before any of the other CPUs are 
  * initialized (i.e. before smp_init()).
  * 
  */
-void __init mtrr_bp_init(void)
+static void __init mtrr_bp_detect(void)
 {
-	init_ifs();
-
 	if (cpu_has_mtrr) {
 		mtrr_if = &generic_mtrr_ops;
 		size_or_mask = 0xff000000;	/* 36 bits */
@@ -701,9 +703,27 @@ void __init mtrr_bp_init(void)
 			break;
 		}
 	}
+}
+
+/**
+ * mtrr_bp_init - initialize mtrrs on the boot CPU
+ *
+ * This needs to be called early; before any of the other CPUs are 
+ * initialized (i.e. before smp_init()).
+ * 
+ */
+void __init mtrr_bp_init(void)
+{
+	init_ifs();
+
+	if (!mtrr_if)
+		mtrr_bp_detect();
 
 	if (mtrr_if) {
-		set_num_var_ranges();
+		/* Xen pv_ops will set the mtrr CPU to unknown, but will
+		 * also initialise the num_var_ranges for us */
+		if (!is_cpu(UNKNOWN))
+			set_num_var_ranges();
 		init_table();
 		if (use_intel())
 			get_mtrr_state();
diff --git a/arch/x86/kernel/cpu/mtrr/xen.c b/arch/x86/kernel/cpu/mtrr/xen.c
new file mode 100644
index 0000000..7011195
--- /dev/null
+++ b/arch/x86/kernel/cpu/mtrr/xen.c
@@ -0,0 +1,57 @@
+#include <linux/init.h>
+#include <linux/proc_fs.h>
+#include <linux/ctype.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+#include <asm/uaccess.h>
+#include <linux/mutex.h>
+
+#include <asm/mtrr.h>
+#include "mtrr.h"
+
+#include <xen/interface/platform.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/hypercall.h>
+
+/* DOM0 TODO: Need to fill in the remaining mtrr methods to have full
+ * working userland mtrr support. */
+static struct mtrr_ops xen_mtrr_ops = {
+	.vendor            = X86_VENDOR_UNKNOWN,
+//	.set               = xen_set_mtrr,
+//	.get               = xen_get_mtrr,
+	.get_free_region   = generic_get_free_region,
+//	.validate_add_page = xen_validate_add_page,
+	.have_wrcomb       = positive_have_wrcomb,
+	.use_intel_if	   = 0
+};
+
+static int __init xen_num_var_ranges(void)
+{
+	int ranges;
+	struct xen_platform_op op;
+
+	for (ranges = 0; ; ranges++) {
+		op.cmd = XENPF_read_memtype;
+		op.u.read_memtype.reg = ranges;
+		if (HYPERVISOR_dom0_op(&op) != 0)
+			break;
+	}
+	return ranges;
+}
+
+void __init xen_init_mtrr(void)
+{
+	struct cpuinfo_x86 *c = &boot_cpu_data;
+
+	if (!is_initial_xendomain())
+		return;
+
+	if ((!cpu_has(c, X86_FEATURE_MTRR)) &&
+	    (!cpu_has(c, X86_FEATURE_K6_MTRR)) &&
+	    (!cpu_has(c, X86_FEATURE_CYRIX_ARR)) &&
+	    (!cpu_has(c, X86_FEATURE_CENTAUR_MCR)))
+		return;
+
+	mtrr_if = &xen_mtrr_ops;
+	num_var_ranges = xen_num_var_ranges();
+}
-- 
1.5.3.4