[xen master] sync CPU state upon final domain destruction

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[xen master] sync CPU state upon final domain destruction

patchbot
commit 24246e1fb7496b830aca8a6a1fd3064ca1e3ebf9
Author:     Jan Beulich <[hidden email]>
AuthorDate: Thu Nov 23 11:38:22 2017 +0100
Commit:     Jan Beulich <[hidden email]>
CommitDate: Thu Nov 23 11:38:22 2017 +0100

    sync CPU state upon final domain destruction
   
    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 <[hidden email]>
    Signed-off-by: Jan Beulich <[hidden email]>
    Acked-by: Andrew Cooper <[hidden email]>
    Release-acked-by: Julien Grall <[hidden email]>
---
 xen/common/domain.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/xen/common/domain.c b/xen/common/domain.c
index 5aebcf2..7484693 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -794,6 +794,14 @@ static void complete_domain_destroy(struct rcu_head *head)
     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 )
--
generated by git-patchbot for /home/xen/git/xen.git#master

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