[Xen-devel] [PATCH 1/3] VMX: Properly adjuest the status of pi descriptor

[Feng Wu <feng.wu@xxxxxxxxx>]

When the last assigned device is dettached from the domain, all
the PI related hooks are removed then, however, the vCPU can be
blocked, switched to another pCPU, etc, all without the aware of
PI. After the next time we attach another device to the domain,
which makes the PI realted hooks avaliable again, the status
of the pi descriptor is not true, we need to properly adjust
it.

Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vmx.c         | 29 ++++++++++++++++++++++++++---
 xen/include/asm-x86/hvm/vmx/vmcs.h |  1 +
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index bc4410f..3fbc7b1 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -107,12 +107,22 @@ void vmx_pi_per_cpu_init(unsigned int cpu)
 static void vmx_vcpu_block(struct vcpu *v)
 {
     unsigned long flags;
-    unsigned int dest;
+    unsigned int dest = cpu_physical_id(v->processor);
     spinlock_t *old_lock;
     spinlock_t *pi_blocking_list_lock =
                &per_cpu(vmx_pi_blocking, v->processor).lock;
     struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc;
 
+    if (v->arch.hvm_vmx.pi_back_from_hotplug == 1)
+    {
+        write_atomic(&pi_desc->ndst,
+                     x2apic_enabled ? dest : MASK_INSR(dest, 
PI_xAPIC_NDST_MASK));
+        write_atomic(&pi_desc->nv, posted_intr_vector);
+        pi_clear_sn(pi_desc);
+
+        v->arch.hvm_vmx.pi_back_from_hotplug = 0;
+    }
+
     spin_lock_irqsave(pi_blocking_list_lock, flags);
     old_lock = cmpxchg(&v->arch.hvm_vmx.pi_blocking.lock, NULL,
                        pi_blocking_list_lock);
@@ -130,8 +140,6 @@ static void vmx_vcpu_block(struct vcpu *v)
 
     ASSERT(!pi_test_sn(pi_desc));
 
-    dest = cpu_physical_id(v->processor);
-
     ASSERT(pi_desc->ndst ==
            (x2apic_enabled ? dest : MASK_INSR(dest, PI_xAPIC_NDST_MASK)));
 
@@ -164,6 +172,16 @@ static void vmx_pi_do_resume(struct vcpu *v)
     unsigned long flags;
     spinlock_t *pi_blocking_list_lock;
     struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc;
+    unsigned int dest = cpu_physical_id(v->processor);
+
+    if (v->arch.hvm_vmx.pi_back_from_hotplug == 1)
+    {
+        write_atomic(&pi_desc->ndst,
+                     x2apic_enabled ? dest : MASK_INSR(dest, 
PI_xAPIC_NDST_MASK));
+        pi_clear_sn(pi_desc);
+
+        v->arch.hvm_vmx.pi_back_from_hotplug = 0;
+    }
 
     ASSERT(!test_bit(_VPF_blocked, &v->pause_flags));
 
@@ -202,9 +220,14 @@ static void vmx_pi_do_resume(struct vcpu *v)
 /* This function is called when pcidevs_lock is held */
 void vmx_pi_hooks_assign(struct domain *d)
 {
+    struct vcpu *v;
+
     if ( !iommu_intpost || !has_hvm_container_domain(d) )
         return;
 
+    for_each_vcpu ( d, v )
+        v->arch.hvm_vmx.pi_back_from_hotplug = 1;
+
     ASSERT(!d->arch.hvm_domain.vmx.vcpu_block);
 
     d->arch.hvm_domain.vmx.vcpu_block = vmx_vcpu_block;
diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h 
b/xen/include/asm-x86/hvm/vmx/vmcs.h
index b54f52f..3feb60a 100644
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
@@ -231,6 +231,7 @@ struct arch_vmx_struct {
      * pCPU and wakeup the related vCPU.
      */
     struct pi_blocking_vcpu pi_blocking;
+    int pi_back_from_hotplug;
 };
 
 int vmx_create_vmcs(struct vcpu *v);
-- 
2.1.0


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