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Re: [Xen-devel] [PATCH] Fix "hda lost interrupt issue" on PAE host

To: "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] Fix "hda lost interrupt issue" on PAE host
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Fri, 21 Apr 2006 09:26:31 +0100
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On 20 Apr 2006, at 21:41, Jiang, Yunhong wrote:

This patch checkes the IDT_VECTORING_INFO_FIELD on vmx_intr_assist, and if it is set, then copy it to VM_ENTRY_INTR_INFO_FIELD and return. Though this method, we can avoid interrupt lost.

More information for IDT_VECTORING_INFO_FIELD can be seen on "Information for VM Exits That Occur During Event Delivery" section on vmx specification.

Hope I explained the issue clearly.

Is there a special value of VM_EXIT_REASON when IDT_VECTORING_INFO_FIELD is in use? I'm guessing not (since the reason tells you what caused the vmexit, not that there was some special action (like event injection) happening at the same time).

If I understand correctly now, presumably if we get to vmx_intr_assist(), see the IDT_VECTORING_INFO_FIELD is valid, but also that we now have *another* exception already queued up in VM_ENTRY_INFO_FIELD, then we should in fact ignore both events and inject a double fault (or go straight to 'triple fault' and crash the domain)? This would happen if, for example, the guest had not properly mapped the IDT in its page tables.


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