From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
commit 8645e56a4ad6dcbf504872db7f14a2f67db88ef2 upstream.
xen_maybe_preempt_hcall() is called from the exception entry point
xen_do_hypervisor_callback with interrupts disabled.
_cond_resched() evades the might_sleep() check in cond_resched() which
would have caught that and schedule_debug() unfortunately lacks a check
for irqs_disabled().
Enable interrupts around the call and use cond_resched() to catch future
issues.
Fixes: fdfd811ddde3 ("x86/xen: allow privcmd hypercalls to be preempted")
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/878skypjrh.fsf@xxxxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/xen/preempt.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/xen/preempt.c
+++ b/drivers/xen/preempt.c
@@ -37,7 +37,9 @@ asmlinkage __visible void xen_maybe_pree
* cpu.
*/
__this_cpu_write(xen_in_preemptible_hcall, false);
- _cond_resched();
+ local_irq_enable();
+ cond_resched();
+ local_irq_disable();
__this_cpu_write(xen_in_preemptible_hcall, true);
}
}
