On 2016/1/18 22:59, Stefano Stabellini wrote: > On Fri, 15 Jan 2016, Shannon Zhao wrote: >> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx> >> >> Move xen_early_init() before efi_init(), then when calling efi_init() >> could initialize Xen specific UEFI. >> >> Check if it runs on Xen hypervisor through the flat dts. >> >> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx> >> --- >> arch/arm/xen/enlighten.c | 56 ++++++++++++++++++++++++++++++++++------------- >> arch/arm64/kernel/setup.c | 2 +- >> 2 files changed, 42 insertions(+), 16 deletions(-) >> >> diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c >> index 4e78c49..5d0fe68 100644 >> --- a/arch/arm/xen/enlighten.c >> +++ b/arch/arm/xen/enlighten.c >> @@ -19,6 +19,7 @@ >> #include <linux/irqreturn.h> >> #include <linux/module.h> >> #include <linux/of.h> >> +#include <linux/of_fdt.h> >> #include <linux/of_irq.h> >> #include <linux/of_address.h> >> #include <linux/cpuidle.h> >> @@ -52,8 +53,6 @@ struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata; >> >> static __read_mostly unsigned int xen_events_irq; >> >> -static __initdata struct device_node *xen_node; >> - >> int xen_remap_domain_gfn_array(struct vm_area_struct *vma, >> unsigned long addr, >> xen_pfn_t *gfn, int nr, >> @@ -222,6 +221,33 @@ static irqreturn_t xen_arm_callback(int irq, void *arg) >> return IRQ_HANDLED; >> } >> >> +static __initdata struct { >> + const char *compat; >> + const char *prefix; >> + const char *version; >> + bool found; >> +} xen_node = {"xen,xen", "xen,xen-", NULL, false}; >> + >> +static int __init fdt_find_xen_node(unsigned long node, const char *uname, >> + int depth, void *data) >> +{ >> + const void *s = NULL; >> + int len; >> + >> + if (depth != 1 || strcmp(uname, "hypervisor") != 0) >> + return 0; >> + >> + if (of_flat_dt_is_compatible(node, xen_node.compat)) >> + xen_node.found = true; >> + >> + s = of_get_flat_dt_prop(node, "compatible", &len); >> + if (strlen(xen_node.prefix) + 3 < len && >> + !strncmp(xen_node.prefix, s, strlen(xen_node.prefix))) >> + xen_node.version = s + strlen(xen_node.prefix); >> + >> + return 0; >> +} >> + >> /* >> * see Documentation/devicetree/bindings/arm/xen.txt for the >> * documentation of the Xen Device Tree format. >> @@ -229,26 +255,18 @@ static irqreturn_t xen_arm_callback(int irq, void *arg) >> #define GRANT_TABLE_PHYSADDR 0 >> void __init xen_early_init(void) >> { >> - int len; >> - const char *s = NULL; >> - const char *version = NULL; >> - const char *xen_prefix = "xen,xen-"; >> - >> - xen_node = of_find_compatible_node(NULL, NULL, "xen,xen"); >> - if (!xen_node) { >> + of_scan_flat_dt(fdt_find_xen_node, NULL); >> + if (!xen_node.found) { >> pr_debug("No Xen support\n"); >> return; >> } >> - 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) { >> + >> + if (xen_node.version == NULL) { >> pr_debug("Xen version not found\n"); >> return; >> } > > This is going to access data within the fdt, after it has been > unflattened (by the unflatten_device_tree call). Is that allowed? > > If that's not allowed, then you could copy the version string to > xen_node.version, rather than just copying the pointer. Otherwise you > could move the version check entirely within fdt_find_xen_node and > remove the version field from xen_node. > A little confused. Since here we move xen_early_init before efi_init and before unflatten_device_tree as well, at this moment in xen_early_init the fdt is flattened. The xen_node.version is only set in fdt_find_xen_node and accessed in xen_early_init. > >> - pr_info("Xen %s support found\n", version); >> + pr_info("Xen %s support found\n", xen_node.version); >> >> xen_domain_type = XEN_HVM_DOMAIN; >> >> @@ -296,6 +314,14 @@ static int __init xen_guest_init(void) >> } >> #endif >> } else { >> + struct device_node *xen_node; >> + >> + xen_node = of_find_compatible_node(NULL, NULL, "xen,xen"); >> + if (!xen_node) { >> + pr_debug("No Xen support\n"); >> + return -ENODEV; >> + } > > It makes sense to move this into a DT specific init function called from > xen_guest_init. Also, given that at this point we know that a Xen node > should be present, it makes sense to return EFAULT on error, instead of > ENODEV. The error message could be changed to something like: "Xen > support was detected before, but it has disappeared" and should be > pr_err. > OK, thanks. > >> xen_events_irq = irq_of_parse_and_map(xen_node, 0); >> } >> >> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c >> index 8119479..a4a2878 100644 >> --- a/arch/arm64/kernel/setup.c >> +++ b/arch/arm64/kernel/setup.c >> @@ -313,6 +313,7 @@ void __init setup_arch(char **cmdline_p) >> */ >> local_async_enable(); >> >> + xen_early_init(); >> efi_init(); >> arm64_memblock_init(); >> >> @@ -334,7 +335,6 @@ void __init setup_arch(char **cmdline_p) >> } else { >> psci_acpi_init(); >> } >> - xen_early_init(); >> >> cpu_read_bootcpu_ops(); >> smp_init_cpus(); > > . > -- Shannon -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html