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Re: [Xen-devel] [PATCH for-next] x86/svm: Correct vm_event API for descriptor accesses
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Alexandru Stefan ISAILA <aisaila@xxxxxxxxxxxxxxx>
- Date: Thu, 28 Nov 2019 14:46:22 +0000
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- Cc: Petre Ovidiu PIRCALABU <ppircalabu@xxxxxxxxxxxxxxx>, Tamas K Lengyel <tamas@xxxxxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Razvan COJOCARU <rcojocaru@xxxxxxxxxxxxxxx>, Adrian Pop <apop@xxxxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
- Delivery-date: Thu, 28 Nov 2019 14:46:31 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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- Thread-topic: [PATCH for-next] x86/svm: Correct vm_event API for descriptor accesses
On 28.11.2019 13:44, Andrew Cooper wrote:
> c/s d0a699a389f1 "x86/monitor: add support for descriptor access events"
> introduced logic looking for what appeared to be exitinfo (not that this
> exists in SVM - exitinfo1 or 2 do), but actually passed the exit IDT vectoring
> information. There is never any IDT vectoring involved in these intercepts so
> the value passed is always zero.
>
> In fact, SVM doesn't provide any information, even in exitinfo1 and 2. Note
> the error in the public API and state that this field is always 0, and drop
> the SVM logic in hvm_monitor_descriptor_access().
>
> In the SVM vmexit handler itself, optimise the switch statement by observing
> that there is a linear transformation between the SVM exit_reason and
> VM_EVENT_DESC_* values. (Bloat-o-meter reports 6028 => 5877 for a saving of
> 151 bytes).
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>
I agree with Tamas, good thing to have that field removed.
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