[Xen-devel] [PATCH v5 1/7] VMX: Statically assign two PI hooks

[Feng Wu <feng.wu@xxxxxxxxx>]

PI hooks: vmx_pi_switch_from() and vmx_pi_switch_to() are
needed even when any previously assigned device is detached
from the domain. Since 'SN' bit is also used to control the
CPU side PI and we change the state of SN bit in these two
functions, then evaluate this bit in vmx_deliver_posted_intr()
when trying to deliver the interrupt in posted way via software.
The problem is if we deassign the hooks while the vCPU is runnable
in the runqueue with 'SN' set, all the furture notificaton event
will be suppressed. This patch makes these two hooks statically
assigned.

Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
---
v5:
- Zap "pi_switch_from" hook

 xen/arch/x86/hvm/vmx/vmx.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 3d330b6..623d5bc 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -147,6 +147,11 @@ static void vmx_pi_switch_from(struct vcpu *v)
     pi_set_sn(pi_desc);
 }
 
+/*
+ * In fact, we can remove this hooks inside itself if no new device is in the
+ * process of getting assigned and "from" hook is NULL. However, it is not
+ * straightforward to find a clear solution, so just leave it here.
+ */
 static void vmx_pi_switch_to(struct vcpu *v)
 {
     struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc;
@@ -221,9 +226,8 @@ void vmx_pi_hooks_deassign(struct domain *d)
     ASSERT(d->arch.hvm_domain.vmx.vcpu_block);
 
     d->arch.hvm_domain.vmx.vcpu_block = NULL;
-    d->arch.hvm_domain.vmx.pi_switch_from = NULL;
-    d->arch.hvm_domain.vmx.pi_switch_to = NULL;
     d->arch.hvm_domain.vmx.pi_do_resume = NULL;
+    d->arch.hvm_domain.vmx.pi_switch_from = NULL;
 }
 
 static int vmx_domain_initialise(struct domain *d)
-- 
2.1.0


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