system_state changes to SYS_STATE_smp_boot before alternative_branches()
is invoked, yet that function, with CET-SS enabled, needs to invoke
modify_xen_mappings(). Convert to check for the number of online CPUs,
just like was done also in 88a037e2cfe1 / fa6dc0879ffd ("page_alloc:
assert IRQs are enabled in heap alloc/free", both instance of which
needed reverting for other reasons).
Fixes: 78e072bc3750 ("x86/mm: avoid inadvertently degrading a TLB flush to
local only")
Reported-by: Andrew Cooper <andrew.coop...@citrix.com>
Signed-off-by: Jan Beulich <jbeul...@suse.com>
---
Only build-tested, as I don't have suitable hardware at hand.
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5074,7 +5074,7 @@ l1_pgentry_t *virt_to_xen_l1e(unsigned l
* map_pages_to_xen() can be called early in boot before any other
* CPUs are online. Use flush_area_local() in this case.
*/
-#define flush_area(v,f) (system_state < SYS_STATE_smp_boot ? \
+#define flush_area(v,f) (num_online_cpus() <= 1 ? \
flush_area_local((const void *)v, f) : \
flush_area_all((const void *)v, f))
