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xen/x86: prevent PVH type from getting clobbered 

Like xen_start_flags, xen_domain_type gets set before .bss gets cleared.
Hence this variable also needs to be prevented from getting put in .bss,
which is possible because XEN_NATIVE is an enumerator evaluating to
zero. Any use prior to init_hvm_pv_info() setting the variable again
would lead to wrong decisions; one such case is xenboot_console_setup()
when called as a result of "earlyprintk=xen".

Use __ro_after_init as more applicable than either __section(".data") or
__read_mostly.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>

Link: https://lore.kernel.org/r/d301677b-6f22-5ae6-bd36-458e1f323d0b@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Jan Beulich 2021-09-30 14:16:15 +02:00 committed by Juergen Gross
parent 97315723c4
commit 9172b5c4a7
1 changed files with 4 additions and 5 deletions
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9
arch/x86/xen/enlighten.c
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@ -52,9 +52,6 @@ DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);
DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);
enum xen_domain_type xen_domain_type = XEN_NATIVE;
EXPORT_SYMBOL_GPL(xen_domain_type);
unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
EXPORT_SYMBOL(machine_to_phys_mapping);
unsigned long machine_to_phys_nr;
@ -69,9 +66,11 @@ __read_mostly int xen_have_vector_callback;
EXPORT_SYMBOL_GPL(xen_have_vector_callback);
/*
* NB: needs to live in .data because it's used by xen_prepare_pvh which runs
* before clearing the bss.
* NB: These need to live in .data or alike because they're used by
* xen_prepare_pvh() which runs before clearing the bss.
*/
enum xen_domain_type __ro_after_init xen_domain_type = XEN_NATIVE;
EXPORT_SYMBOL_GPL(xen_domain_type);
uint32_t xen_start_flags __section(".data") = 0;
EXPORT_SYMBOL(xen_start_flags);