Re: [Xen-devel] [PATCH] x86/hvm: implement save/restore for posted interrupts

["Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>]

Olaf Hering wrote on 2014-07-17:
> On Wed, Jul 16, Tian, Kevin wrote:
> 
>> could you figure out the reason? irr->pir propagation should happen
>> automatically when injecting a pending irr, which is supposed to be
>> triggered in the restore path. Otherwise I don't understand how it's
>> handled even w/o pir concept...
> 
> I can probably do that. And I think initially I just changed
> lapic_save_regs, which was not enough. I think in the end the reason
> is that with posted irqs the code paths are different and just having IRR set 
> is not enough.

It doesn't make sense. PIR is more like a tmp_IRR. All interrupts pending in 
PIR will finally sync to IRR by hardware. In your case, you already record it 
in IRR, it should be enough.
The problem I am seeing is that the eoi_exit_bitmap need to be setup correct 
after migration, please try attached patch to see whether it solves your 
problem:

diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index cd7e872..d9368a7 100644
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -131,7 +131,7 @@ void vlapic_set_irq(struct vlapic *vlapic, uint8_t vec, 
uint8_t trig)
         vlapic_set_vector(vec, &vlapic->regs->data[APIC_TMR]);
 
     if ( hvm_funcs.update_eoi_exit_bitmap )
-        hvm_funcs.update_eoi_exit_bitmap(target, vec, trig);
+        hvm_funcs.update_eoi_exit_bitmap(target, vec, trig, 0);
 
     if ( hvm_funcs.deliver_posted_intr )
         hvm_funcs.deliver_posted_intr(target, vec);
@@ -1179,6 +1179,9 @@ static int lapic_save_regs(struct domain *d, 
hvm_domain_context_t *h)
 
     for_each_vcpu ( d, v )
     {
+        if ( hvm_funcs.sync_pir_to_irr )
+            hvm_funcs.sync_pir_to_irr(v);
+
         s = vcpu_vlapic(v);
         if ( (rc = hvm_save_entry(LAPIC_REGS, v->vcpu_id, h, s->regs)) != 0 )
             break;
@@ -1230,6 +1233,9 @@ static int lapic_load_regs(struct domain *d, 
hvm_domain_context_t *h)
     if ( hvm_load_entry(LAPIC_REGS, h, s->regs) != 0 ) 
         return -EINVAL;
 
+    if ( hvm_funcs.update_eoi_exit_bitmap )
+        hvm_funcs.update_eoi_exit_bitmap(v, 0, 0, 1);
+
     if ( hvm_funcs.process_isr )
         hvm_funcs.process_isr(vlapic_find_highest_isr(s), v);
 
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 2caa04a..9a2dfd6 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1567,12 +1567,28 @@ static void vmx_set_info_guest(struct vcpu *v)
     vmx_vmcs_exit(v);
 }
 
-static void vmx_update_eoi_exit_bitmap(struct vcpu *v, u8 vector, u8 trig)
+static void vmx_rebuild_eoi_exit_bitmap(struct vcpu *v)
 {
-    if ( trig )
-        vmx_set_eoi_exit_bitmap(v, vector);
+    struct vlapic *vlapic = vcpu_vlapic(v);
+    unsigned int vector;
+
+    for ( vector = 0; vector < NR_VECTORS; vector++ )
+        if ( vlapic_test_vector(vector, &vlapic->regs->data[APIC_IRR]) )
+            set_bit(vector, v->arch.hvm_vmx.eoi_exit_bitmap);
+}
+
+static void vmx_update_eoi_exit_bitmap(struct vcpu *v, u8 vector,
+                                       u8 trig, bool_t rebuild)
+{
+    if ( rebuild )
+        vmx_rebuild_eoi_exit_bitmap(v);
     else
-        vmx_clear_eoi_exit_bitmap(v, vector);
+    {
+        if ( trig )
+            vmx_set_eoi_exit_bitmap(v, vector);
+        else
+            vmx_clear_eoi_exit_bitmap(v, vector);
+    }
 }
 
 static int vmx_virtual_intr_delivery_enabled(void)
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index 0ebd478..3e2e365 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -189,7 +189,8 @@ struct hvm_function_table {
     void (*nhvm_domain_relinquish_resources)(struct domain *d);
 
     /* Virtual interrupt delivery */
-    void (*update_eoi_exit_bitmap)(struct vcpu *v, u8 vector, u8 trig);
+    void (*update_eoi_exit_bitmap)(struct vcpu *v, u8 vector,
+                                   u8 trig, bool_t rebuild);
     int (*virtual_intr_delivery_enabled)(void);
     void (*process_isr)(int isr, struct vcpu *v);
     void (*deliver_posted_intr)(struct vcpu *v, u8 vector);
diff --git a/xen/include/asm-x86/hvm/vlapic.h b/xen/include/asm-x86/hvm/vlapic.h
index 66f0aff..2a83a1e 100644
--- a/xen/include/asm-x86/hvm/vlapic.h
+++ b/xen/include/asm-x86/hvm/vlapic.h
@@ -58,6 +58,8 @@
 
 #define VEC_POS(v) ((v) % 32)
 #define REG_POS(v) (((v) / 32) * 0x10)
+#define vlapic_test_vector(vec, bitmap)                         \
+    test_bit(VEC_POS(vec), (uint32_t *)((bitmap) + REG_POS(vec)))
 #define vlapic_test_and_set_vector(vec, bitmap)                         \
     test_and_set_bit(VEC_POS(vec), (uint32_t *)((bitmap) + REG_POS(vec)))
 #define vlapic_test_and_clear_vector(vec, bitmap)

Best regards,
Yang


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