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Re: [Xen-devel] [PATCH] make HVM PIC emulation code SMP-safe

Well, that would make it behave like a *real* PIC, wired through to CPU0's INT pin, right? So it sounds good to me, especially if we are currently spraying PIC interrupts across all VCPUs. And it's even better if it avoids requiring locking on the vmentry path.

 -- Keir

On 16 May 2006, at 06:20, Dong, Eddie wrote:

 For the PIC I/O access, do we need lock protect? But for IRQ generation, i.e. cpu_get_interrupt, how about following for simplicity (not tested)?
diff -r 1e3977e029fd xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c    Mon May 08 19:21:41 2006 +0100
+++ b/xen/arch/x86/hvm/hvm.c    Tue May 16 13:18:04 2006 +0800
@@ -248,7 +248,7 @@ int cpu_get_interrupt(struct vcpu *v, in
         return intno;
     /* read the irq from the PIC */
-    if ( (intno = cpu_get_pic_interrupt(v, type)) != -1 )
+    if ( v->vcpu_id == 0 && (intno = cpu_get_pic_interrupt(v, type)) != -1 )
         return intno;
     return -1;

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