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Re: [Xen-devel] [PATCH v2] sync CPU state upon final domain destruction
- To: Jan Beulich <JBeulich@xxxxxxxx>, Julien Grall <julien.grall@xxxxxxx>
- From: Julien Grall <julien.grall@xxxxxxxxxx>
- Date: Wed, 22 Nov 2017 16:04:55 +0000
- Cc: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wei.liu2@xxxxxxxxxx>, Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>, Tim Deegan <tim@xxxxxxx>, Dario Faggioli <raistlin@xxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Wed, 22 Nov 2017 16:05:11 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
Hi,
On 11/22/2017 01:00 PM, Jan Beulich wrote:
On 22.11.17 at 13:39, <JBeulich@xxxxxxxx> wrote:
See the code comment being added for why we need this.
This is being placed here to balance between the desire to prevent
future similar issues (the risk of which would grow if it was put
further down the call stack, e.g. in vmx_vcpu_destroy()) and the
intention to limit the performance impact (otherwise it could also go
into rcu_do_batch(), paralleling the use in do_tasklet_work()).
Reported-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
I'm sorry, Julien, I did forget to Cc you (for 4.10 inclusion).
Release-acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
Cheers,
---
v2: Move from vmx_vcpu_destroy() to complete_domain_destroy().
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -794,6 +794,14 @@ static void complete_domain_destroy(stru
struct vcpu *v;
int i;
+ /*
+ * Flush all state for the vCPU previously having run on the current CPU.
+ * This is in particular relevant for x86 HVM ones on VMX, so that this
+ * flushing of state won't happen from the TLB flush IPI handler behind
+ * the back of a vmx_vmcs_enter() / vmx_vmcs_exit() section.
+ */
+ sync_local_execstate();
+
for ( i = d->max_vcpus - 1; i >= 0; i-- )
{
if ( (v = d->vcpu[i]) == NULL )
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