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Re: [Xen-devel] [PATCH v3 18/19] xen/arm: Prevent slipping hypervisor SError to guest
On 2017/4/1 2:43, Julien Grall wrote:
Hi Stefano,
On 03/31/2017 07:42 PM, Stefano Stabellini wrote:
On Fri, 31 Mar 2017, Julien Grall wrote:
Hi Wei,
On 31/03/17 14:07, Wei Chen wrote:
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_CHECK_PENDING_VSERROR 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>
---
v2->v3:
1. Use alternative instead of check serror_op to skip sychronizing
SErrors
while option is NOT "DIVERSE".
2. Disable Abort/SError before returning to guest.
---
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 2c610c4..8f1a0cd 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -2936,6 +2936,19 @@ 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_CHECK_PENDING_VSERROR 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_CHECK_PENDING_VSERROR);
The feature name SKIP_CHECK_PENDING_VSERROR does not make sense here
because
we are not synchronizing guest SError.
I am happy to re-use the same feature, but this would need to rename.
Maybe
SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT?
Just for clarity, you are suggest to use the same cpu_hwcaps feature
here and in patch #8, as Wei is doing, but we a different name. That's
fine by me.
That's correct. I thought the name "SKIP_CHECK_PENDING_VSERROR" does not
match the behavior here.
Yes, I will rename it.
Cheers,
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