[Xen-changelog] [xen master] VMX: fixup PI descriptor when cpu is offline

[patchbot@xxxxxxx]

commit 92fc8d10f5b59bd59455962b41953d6ca3ecfd16
Author:     Feng Wu <feng.wu@xxxxxxxxx>
AuthorDate: Fri Apr 7 15:37:55 2017 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Apr 7 15:37:55 2017 +0200

    VMX: fixup PI descriptor when cpu is offline
    
    When cpu is offline, we need to move all the vcpus in its blocking
    list to another online cpu, this patch handles it.
    
    Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
    Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vmcs.c       |  1 +
 xen/arch/x86/hvm/vmx/vmx.c        | 70 +++++++++++++++++++++++++++++++++++++++
 xen/include/asm-x86/hvm/vmx/vmx.h |  1 +
 3 files changed, 72 insertions(+)

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 934674c..99c77b9 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -591,6 +591,7 @@ void vmx_cpu_dead(unsigned int cpu)
     vmx_free_vmcs(per_cpu(vmxon_region, cpu));
     per_cpu(vmxon_region, cpu) = 0;
     nvmx_cpu_dead(cpu);
+    vmx_pi_desc_fixup(cpu);
 }
 
 int vmx_cpu_up(void)
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 36d2aaa..01acd5a 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -199,6 +199,76 @@ static void vmx_pi_do_resume(struct vcpu *v)
     vmx_pi_unblock_vcpu(v);
 }
 
+void vmx_pi_desc_fixup(unsigned int cpu)
+{
+    unsigned int new_cpu, dest;
+    unsigned long flags;
+    struct arch_vmx_struct *vmx, *tmp;
+    spinlock_t *new_lock, *old_lock = &per_cpu(vmx_pi_blocking, cpu).lock;
+    struct list_head *blocked_vcpus = &per_cpu(vmx_pi_blocking, cpu).list;
+
+    if ( !iommu_intpost )
+        return;
+
+    /*
+     * We are in the context of CPU_DEAD or CPU_UP_CANCELED notification,
+     * and it is impossible for a second CPU go down in parallel. So we
+     * can safely acquire the old cpu's lock and then acquire the new_cpu's
+     * lock after that.
+     */
+    spin_lock_irqsave(old_lock, flags);
+
+    list_for_each_entry_safe(vmx, tmp, blocked_vcpus, pi_blocking.list)
+    {
+        /*
+         * Suppress notification or we may miss an interrupt when the
+         * target cpu is dying.
+         */
+        pi_set_sn(&vmx->pi_desc);
+
+        /*
+         * Check whether a notification is pending before doing the
+         * movement, if that is the case we need to wake up it directly
+         * other than moving it to the new cpu's list.
+         */
+        if ( pi_test_on(&vmx->pi_desc) )
+        {
+            list_del(&vmx->pi_blocking.list);
+            vmx->pi_blocking.lock = NULL;
+            vcpu_unblock(container_of(vmx, struct vcpu, arch.hvm_vmx));
+        }
+        else
+        {
+            /*
+             * We need to find an online cpu as the NDST of the PI descriptor, 
it
+             * doesn't matter whether it is within the cpupool of the domain or
+             * not. As long as it is online, the vCPU will be woken up once the
+             * notification event arrives.
+             */
+            new_cpu = cpumask_any(&cpu_online_map);
+            new_lock = &per_cpu(vmx_pi_blocking, new_cpu).lock;
+
+            spin_lock(new_lock);
+
+            ASSERT(vmx->pi_blocking.lock == old_lock);
+
+            dest = cpu_physical_id(new_cpu);
+            write_atomic(&vmx->pi_desc.ndst,
+                         x2apic_enabled ? dest : MASK_INSR(dest, 
PI_xAPIC_NDST_MASK));
+
+            list_move(&vmx->pi_blocking.list,
+                      &per_cpu(vmx_pi_blocking, new_cpu).list);
+            vmx->pi_blocking.lock = new_lock;
+
+            spin_unlock(new_lock);
+        }
+
+        pi_clear_sn(&vmx->pi_desc);
+    }
+
+    spin_unlock_irqrestore(old_lock, flags);
+}
+
 /*
  * To handle posted interrupts correctly, we need to set the following
  * state:
diff --git a/xen/include/asm-x86/hvm/vmx/vmx.h 
b/xen/include/asm-x86/hvm/vmx/vmx.h
index 2b781ab..5ead57c 100644
--- a/xen/include/asm-x86/hvm/vmx/vmx.h
+++ b/xen/include/asm-x86/hvm/vmx/vmx.h
@@ -597,6 +597,7 @@ void free_p2m_hap_data(struct p2m_domain *p2m);
 void p2m_init_hap_data(struct p2m_domain *p2m);
 
 void vmx_pi_per_cpu_init(unsigned int cpu);
+void vmx_pi_desc_fixup(unsigned int cpu);
 
 void vmx_pi_hooks_assign(struct domain *d);
 void vmx_pi_hooks_deassign(struct domain *d);
--
generated by git-patchbot for /home/xen/git/xen.git#master

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