[Xen-devel] [PATCH 2/2] arm, arm64/xen: move Xen initialization earlier

[Julien Grall <julien.grall@xxxxxxxxxx>]

From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

Currently, Xen is initialized/discovered in an initcall. This doesn't
allow us to support earlyprintk or choosing the preferred console when
running on Xen.

The current function xen_guest_init is now split in 2 parts:
    - xen_early_init: Check if there is a Xen node in the device tree
    and setup domain type
    - xen_guest_init: Retrieve the information from the device node and
    initialize Xen (grant table, shared page...)

The former is called in setup_arch, while the latter is an initcall.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>

---
    It's based on a patch sent by Stefano nearly 2 years ago [1].

    [1] http://lists.xen.org/archives/html/xen-devel/2013-08/msg02960.html
---
 arch/arm/include/asm/xen/hypervisor.h |  8 +++++
 arch/arm/kernel/setup.c               |  2 ++
 arch/arm/xen/enlighten.c              | 58 ++++++++++++++++++++---------------
 arch/arm64/kernel/setup.c             |  2 ++
 4 files changed, 46 insertions(+), 24 deletions(-)

diff --git a/arch/arm/include/asm/xen/hypervisor.h 
b/arch/arm/include/asm/xen/hypervisor.h
index 1317ee4..04ff8e7 100644
--- a/arch/arm/include/asm/xen/hypervisor.h
+++ b/arch/arm/include/asm/xen/hypervisor.h
@@ -1,6 +1,8 @@
 #ifndef _ASM_ARM_XEN_HYPERVISOR_H
 #define _ASM_ARM_XEN_HYPERVISOR_H
 
+#include <linux/init.h>
+
 extern struct shared_info *HYPERVISOR_shared_info;
 extern struct start_info *xen_start_info;
 
@@ -18,4 +20,10 @@ static inline enum paravirt_lazy_mode 
paravirt_get_lazy_mode(void)
 
 extern struct dma_map_ops *xen_dma_ops;
 
+#ifdef CONFIG_XEN
+void __init 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 e55408e..8b59d0d 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -46,6 +46,7 @@
 #include <asm/cacheflush.h>
 #include <asm/cachetype.h>
 #include <asm/tlbflush.h>
+#include <asm/xen/hypervisor.h>
 
 #include <asm/prom.h>
 #include <asm/mach/arch.h>
@@ -936,6 +937,7 @@ 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 90101c8..0abeefa 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -53,6 +53,8 @@ EXPORT_SYMBOL_GPL(xen_platform_pci_unplug);
 
 static unsigned int xen_events_irq;
 
+static __initdata struct device_node *xen_node;
+
 /* map fgmfn of domid to lpfn in the current domain */
 static int map_foreign_page(unsigned long lpfn, unsigned long fgmfn,
                            unsigned int domid)
@@ -222,42 +224,28 @@ static irqreturn_t xen_arm_callback(int irq, void *arg)
  * documentation of the Xen Device Tree format.
  */
 #define GRANT_TABLE_PHYSADDR 0
-static int __init xen_guest_init(void)
+void __init xen_early_init(void)
 {
-       struct xen_add_to_physmap xatp;
-       static struct shared_info *shared_info_page = 0;
-       struct device_node *node;
        int len;
        const char *s = NULL;
        const char *version = NULL;
        const char *xen_prefix = "xen,xen-";
-       struct resource res;
-       phys_addr_t grant_frames;
 
-       node = of_find_compatible_node(NULL, NULL, "xen,xen");
-       if (!node) {
+       xen_node = of_find_compatible_node(NULL, NULL, "xen,xen");
+       if (!xen_node) {
                pr_debug("No Xen support\n");
-               return 0;
+               return;
        }
-       s = of_get_property(node, "compatible", &len);
+       s = of_get_property(xen_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;
-       }
-       if (of_address_to_resource(node, GRANT_TABLE_PHYSADDR, &res))
-               return 0;
-       grant_frames = res.start;
-       xen_events_irq = irq_of_parse_and_map(node, 0);
-       if (!xen_events_irq) {
-               pr_debug("Xen event channel interrupt not found\n");
-               return -ENODEV;
+               return;
        }
 
-       pr_info("Xen %s support found, events_irq=%d gnttab_frame=%pa\n",
-                       version, xen_events_irq, &grant_frames);
+       pr_info("Xen %s support found\n", version);
 
        xen_domain_type = XEN_HVM_DOMAIN;
 
@@ -267,10 +255,32 @@ static int __init xen_guest_init(void)
                xen_start_info->flags |= SIF_INITDOMAIN|SIF_PRIVILEGED;
        else
                xen_start_info->flags &= ~(SIF_INITDOMAIN|SIF_PRIVILEGED);
+}
+
+static int __init xen_guest_init(void)
+{
+       struct xen_add_to_physmap xatp;
+       struct shared_info *shared_info_page = NULL;
+       struct resource res;
+       phys_addr_t grant_frames;
+
+       if (!xen_domain())
+               return 0;
+
+       if (of_address_to_resource(xen_node, GRANT_TABLE_PHYSADDR, &res)) {
+               pr_err("Xen grant table base address not found\n");
+               return -ENODEV;
+       }
+       grant_frames = res.start;
+
+       xen_events_irq = irq_of_parse_and_map(xen_node, 0);
+       if (!xen_events_irq) {
+               pr_err("Xen event channel interrupt not found\n");
+               return -ENODEV;
+       }
+
+       shared_info_page = (struct shared_info *)get_zeroed_page(GFP_KERNEL);
 
-       if (!shared_info_page)
-               shared_info_page = (struct shared_info *)
-                       get_zeroed_page(GFP_KERNEL);
        if (!shared_info_page) {
                pr_err("not enough memory\n");
                return -ENOMEM;
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index e8420f6..c00ae01 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -62,6 +62,7 @@
 #include <asm/memblock.h>
 #include <asm/psci.h>
 #include <asm/efi.h>
+#include <asm/xen/hypervisor.h>
 
 unsigned int processor_id;
 EXPORT_SYMBOL(processor_id);
@@ -388,6 +389,7 @@ void __init setup_arch(char **cmdline_p)
        unflatten_device_tree();
 
        psci_init();
+       xen_early_init();
 
        cpu_read_bootcpu_ops();
 #ifdef CONFIG_SMP
-- 
2.1.0


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