[Xen-devel] [PATCH v3.1 03/15] xen/x86: allow calling {sh/hap}_set_allocation with the idle domain

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

... and using the "preempted" parameter. The solution relies on just calling
softirq_pending if the current domain is the idle domain. If such preemption
happens, the caller should then call process_pending_softirqs in order to
drain the pending softirqs, and then call {sh/hap}_set_allocation again to
continue with it's execution.

This allows us to call *_set_allocation() when building domain 0.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>
---
Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
Changes since v2:
 - Fix commit message.
---
 xen/arch/x86/mm/hap/hap.c       | 4 +++-
 xen/arch/x86/mm/shadow/common.c | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c
index f099e94..0645521 100644
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -379,7 +379,9 @@ hap_set_allocation(struct domain *d, unsigned int pages, 
int *preempted)
             break;
 
         /* Check to see if we need to yield and try again */
-        if ( preempted && hypercall_preempt_check() )
+        if ( preempted &&
+             (is_idle_vcpu(current) ? softirq_pending(smp_processor_id()) :
+                                      hypercall_preempt_check()) )
         {
             *preempted = 1;
             return 0;
diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index 065bdc7..b2e99c2 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -1679,7 +1679,9 @@ static int sh_set_allocation(struct domain *d,
             break;
 
         /* Check to see if we need to yield and try again */
-        if ( preempted && hypercall_preempt_check() )
+        if ( preempted &&
+             (is_idle_vcpu(current) ? softirq_pending(smp_processor_id()) :
+                                      hypercall_preempt_check()) )
         {
             *preempted = 1;
             return 0;
-- 
2.7.4 (Apple Git-66)


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