[Xen-devel] [PATCH v4 18/19] xen/arm: Prevent slipping hypervisor SError to guest

[Wei Chen <Wei.Chen@xxxxxxx>]

If there is a pending SError while we're returning from trap. If the
SError handle option is "DIVERSE", we have to prevent slipping this
hypervisor SError to guest. So we have to use the dsb/isb to guarantee
that the pending hypervisor SError would be caught in hypervisor before
return to guest.

In previous patch, we will set SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT to
cpu_hwcaps when option is NOT "DIVERSE". This means we can use the
alternative to skip synchronizing SErrors for other SErrors handle options.

Because we have umasked the Abort/SError bit in previous patch. We have
to disable the Abort/SError before returning to guest as we have done
for IRQ.

Signed-off-by: Wei Chen <Wei.Chen@xxxxxxx>
---
 xen/arch/arm/traps.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index c092e66..c8163db 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -2989,6 +2989,19 @@ asmlinkage void leave_hypervisor_tail(void)
         local_irq_disable();
         if (!softirq_pending(smp_processor_id())) {
             gic_inject();
+
+            /*
+             * If the SErrors handle option is "DIVERSE", we have to prevent
+             * slipping the hypervisor SError to guest. In this option, before
+             * returning from trap, we have to synchronize SErrors to guarantee
+             * that the pending SError would be caught in hypervisor.
+             *
+             * If option is NOT "DIVERSE", SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT
+             * will be set to cpu_hwcaps. This means we can use the alternative
+             * to skip synchronizing SErrors for other SErrors handle options.
+             */
+            SYNCHRONIZE_SERROR(SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT);
+
             return;
         }
         local_irq_enable();
-- 
2.7.4


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