[Xen-devel] [PATCH 12/12] xen/mtrr: Add mtrr_if support for Xen mtrr

[stefano.stabellini@xxxxxxxxxxxxx]

From: Stephen Tweedie <sct@xxxxxxxxxx>

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.)

[ Impact: add basic MTRR support ]

Signed-off-by: Stephen Tweedie <sct@xxxxxxxxxx>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/mtrr/Makefile |    2 +-
 arch/x86/kernel/cpu/mtrr/main.c   |    3 +
 arch/x86/kernel/cpu/mtrr/mtrr.h   |    7 ++
 arch/x86/kernel/cpu/mtrr/xen.c    |  110 +++++++++++++++++++++++++++++++++++++
 4 files changed, 121 insertions(+), 1 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 ad9e5ed..e955771 100644
--- a/arch/x86/kernel/cpu/mtrr/Makefile
+++ b/arch/x86/kernel/cpu/mtrr/Makefile
@@ -1,3 +1,3 @@
 obj-y          := main.o if.o generic.o cleanup.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 91f8f62..fcfa520 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -727,6 +727,9 @@ void __init mtrr_bp_init(void)
                }
        }
 
+       /* Let Xen code override the above if it wants */
+       xen_init_mtrr();
+
        if (mtrr_if) {
                num_var_ranges = mtrr_if->num_var_ranges();
                init_table();
diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.h b/arch/x86/kernel/cpu/mtrr/mtrr.h
index add8abe..8f0693e 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.h
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.h
@@ -74,6 +74,13 @@ void mtrr_wrmsr(unsigned, unsigned, unsigned);
 int amd_init_mtrr(void);
 int cyrix_init_mtrr(void);
 int centaur_init_mtrr(void);
+#ifdef CONFIG_XEN
+void xen_init_mtrr(void);
+#else
+static inline void xen_init_mtrr(void)
+{
+}
+#endif
 
 extern int changed_by_mtrr_cleanup;
 extern int mtrr_cleanup(unsigned address_bits);
diff --git a/arch/x86/kernel/cpu/mtrr/xen.c b/arch/x86/kernel/cpu/mtrr/xen.c
new file mode 100644
index 0000000..fec3b0a
--- /dev/null
+++ b/arch/x86/kernel/cpu/mtrr/xen.c
@@ -0,0 +1,110 @@
+#include <linux/init.h>
+#include <linux/mm.h>
+
+#include <asm/pat.h>
+#include <asm/mtrr.h>
+
+#include "mtrr.h"
+
+#include <xen/xen.h>
+#include <xen/interface/platform.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/hypercall.h>
+
+static void xen_set_mtrr(unsigned int reg, unsigned long base,
+                        unsigned long size, mtrr_type type)
+{
+       struct xen_platform_op op;
+       int error;
+
+       /* mtrr_ops->set() is called once per CPU,
+        * but Xen's ops apply to all CPUs.
+        */
+       if (smp_processor_id())
+               return;
+
+       if (size == 0) {
+               op.cmd = XENPF_del_memtype;
+               op.u.del_memtype.handle = 0;
+               op.u.del_memtype.reg    = reg;
+       } else {
+               op.cmd = XENPF_add_memtype;
+               op.u.add_memtype.mfn     = base;
+               op.u.add_memtype.nr_mfns = size;
+               op.u.add_memtype.type    = type;
+       }
+
+       error = HYPERVISOR_dom0_op(&op);
+       BUG_ON(error != 0);
+}
+
+static void xen_get_mtrr(unsigned int reg, unsigned long *base,
+                        unsigned long *size, mtrr_type *type)
+{
+       struct xen_platform_op op;
+
+       op.cmd = XENPF_read_memtype;
+       op.u.read_memtype.reg = reg;
+       if (HYPERVISOR_dom0_op(&op) != 0) {
+               *base = 0;
+               *size = 0;
+               *type = 0;
+               return;
+       }
+
+       *size = op.u.read_memtype.nr_mfns;
+       *base = op.u.read_memtype.mfn;
+       *type = op.u.read_memtype.type;
+}
+
+static int __init xen_num_var_ranges(void)
+{
+       int ranges;
+       struct xen_platform_op op;
+
+       op.cmd = XENPF_read_memtype;
+
+       for (ranges = 0; ; ranges++) {
+               op.u.read_memtype.reg = ranges;
+               if (HYPERVISOR_dom0_op(&op) != 0)
+                       break;
+       }
+       return ranges;
+}
+
+/*
+ * 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,
+       .get_free_region   = generic_get_free_region,
+       .set               = xen_set_mtrr,
+       .get               = xen_get_mtrr,
+       .have_wrcomb       = positive_have_wrcomb,
+       .validate_add_page = generic_validate_add_page,
+       .use_intel_if      = 0,
+       .num_var_ranges    = xen_num_var_ranges,
+};
+
+void __init xen_init_mtrr(void)
+{
+       /* 
+        * Check that we're running under Xen, and privileged enough
+        * to play with MTRRs.
+        */
+       if (!xen_initial_domain())
+               return;
+
+       /* 
+        * Check that the CPU has an MTRR implementation we can
+        * support.
+        */
+       if (cpu_has_mtrr ||
+           cpu_has_k6_mtrr ||
+           cpu_has_cyrix_arr ||
+           cpu_has_centaur_mcr) {
+               mtrr_if = &xen_mtrr_ops;
+               pat_init();
+       }
+}
-- 
1.5.6.5


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