[Xen-devel] [PATCH v2] xen/arm: introduce xen_early_init, use PSCI on xen

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Split xen_guest_init in two functions, one of them (xen_early_init) is
going to be called very early from setup_arch.

Change machine_desc->smp_init to xen_smp_init if Xen is present on the
platform. xen_smp_init just sets smp_ops to psci_smp_ops.

XEN selects ARM_PSCI.

This patch is based on "xen/arm: move to mach-virt and support SMP"
(http://marc.info/?l=linux-kernel&m=136629656432231&w=2)
and "arm: introduce psci_smp_ops"
(http://marc.info/?l=linux-kernel&m=136629750732674&w=2).

Changes in v2:
- fix missing return value for xen_smp_init ifndef CONFIG_SMP.

A git tag for this patch is available here:

git://git.kernel.org/pub/scm/linux/kernel/git/sstabellini/xen.git 
3.9-rc3-psci-xen-2-tag


Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
CC: xen-devel@xxxxxxxxxxxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx
CC: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
CC: will.deacon@xxxxxxx
CC: arnd@xxxxxxxx
CC: nicolas.pitre@xxxxxxxxxx
CC: rob.herring@xxxxxxxxxxx
CC: linux@xxxxxxxxxxxxxxxx
CC: olof@xxxxxxxxx

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 arch/arm/Kconfig                      |    1 +
 arch/arm/include/asm/xen/hypervisor.h |    6 +++++
 arch/arm/kernel/setup.c               |    3 ++
 arch/arm/xen/enlighten.c              |   39 ++++++++++++++++++++++++++------
 4 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 2c3bdce..344e299 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1892,6 +1892,7 @@ config XEN
        depends on ARM && AEABI && OF
        depends on CPU_V7 && !CPU_V6
        depends on !GENERIC_ATOMIC64
+       select ARM_PSCI
        help
          Say Y if you want to run Linux in a Virtual Machine on Xen on ARM.
 
diff --git a/arch/arm/include/asm/xen/hypervisor.h 
b/arch/arm/include/asm/xen/hypervisor.h
index d7ab99a..17b3ea2 100644
--- a/arch/arm/include/asm/xen/hypervisor.h
+++ b/arch/arm/include/asm/xen/hypervisor.h
@@ -16,4 +16,10 @@ static inline enum paravirt_lazy_mode 
paravirt_get_lazy_mode(void)
        return PARAVIRT_LAZY_NONE;
 }
 
+#ifdef CONFIG_XEN
+void xen_early_init(void);
+#else
+static inline void xen_early_init(void) { return; }
+#endif
+
 #endif /* _ASM_ARM_XEN_HYPERVISOR_H */
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 22cc863..3dcd357 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -55,6 +55,8 @@
 #include <asm/unwind.h>
 #include <asm/memblock.h>
 #include <asm/virt.h>
+#include <asm/xen/hypervisor.h>
+#include <xen/xen.h>
 
 #include "atags.h"
 #include "tcm.h"
@@ -768,6 +770,7 @@ void __init setup_arch(char **cmdline_p)
 
        arm_dt_init_cpu_maps();
        psci_init();
+       xen_early_init();
 #ifdef CONFIG_SMP
        if (is_smp()) {
                if (!mdesc->smp_init || !mdesc->smp_init()) {
diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index b002822..c1fe6f3 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -11,6 +11,8 @@
 #include <xen/xenbus.h>
 #include <xen/page.h>
 #include <xen/xen-ops.h>
+#include <asm/mach/arch.h>
+#include <asm/psci.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
 #include <linux/interrupt.h>
@@ -176,11 +178,36 @@ static int __init xen_secondary_init(unsigned int cpu)
        return 0;
 }
 
+static bool __init xen_smp_init(void)
+{
+#ifdef CONFIG_SMP
+       /* If we are running on Xen, use PSCI if available.
+        * In any case do not try to use the native smp_ops. */
+       if (psci_smp_available())
+               smp_set_ops(&psci_smp_ops);
+#endif
+       return true;
+}
+
 /*
  * see Documentation/devicetree/bindings/arm/xen.txt for the
  * documentation of the Xen Device Tree format.
  */
 #define GRANT_TABLE_PHYSADDR 0
+void __init xen_early_init(void)
+{
+       struct device_node *node;
+
+       node = of_find_compatible_node(NULL, NULL, "xen,xen");
+       if (!node) {
+               pr_debug("No Xen support\n");
+               return;
+       }
+
+       xen_domain_type = XEN_HVM_DOMAIN;
+       machine_desc->smp_init = xen_smp_init;
+}
+
 static int __init xen_guest_init(void)
 {
        struct xen_add_to_physmap xatp;
@@ -194,25 +221,21 @@ static int __init xen_guest_init(void)
        int i;
 
        node = of_find_compatible_node(NULL, NULL, "xen,xen");
-       if (!node) {
-               pr_debug("No Xen support\n");
-               return 0;
-       }
+
        s = of_get_property(node, "compatible", &len);
        if (strlen(xen_prefix) + 3  < len &&
                        !strncmp(xen_prefix, s, strlen(xen_prefix)))
                version = s + strlen(xen_prefix);
        if (version == NULL) {
-               pr_debug("Xen version not found\n");
-               return 0;
+               pr_warn("Xen version not found\n");
+               return -EINVAL;
        }
        if (of_address_to_resource(node, GRANT_TABLE_PHYSADDR, &res))
-               return 0;
+               return -EINVAL;
        xen_hvm_resume_frames = res.start >> PAGE_SHIFT;
        xen_events_irq = irq_of_parse_and_map(node, 0);
        pr_info("Xen %s support found, events_irq=%d gnttab_frame_pfn=%lx\n",
                        version, xen_events_irq, xen_hvm_resume_frames);
-       xen_domain_type = XEN_HVM_DOMAIN;
 
        xen_setup_features();
        if (xen_feature(XENFEAT_dom0))
-- 
1.7.2.5


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