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RE: [PATCH] x86/vmx: Partially revert "x86/vmx: implement Notify VM Exit"
- To: "andrew.cooper3@xxxxxxxxxx" <andrew.cooper3@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
- Date: Thu, 19 Jan 2023 05:52:31 +0000
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- Cc: "andrew.cooper3@xxxxxxxxxx" <andrew.cooper3@xxxxxxxxxx>, "Beulich, Jan" <JBeulich@xxxxxxxx>, Pau Monné, Roger <roger.pau@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>
- Delivery-date: Thu, 19 Jan 2023 05:53:02 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Thread-index: AQHZK3RJ/0ZZPj3GFkGObjjpGm11Tq6lPW7Q
- Thread-topic: [PATCH] x86/vmx: Partially revert "x86/vmx: implement Notify VM Exit"
> From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Sent: Thursday, January 19, 2023 3:37 AM
>
> The original patch tried to do two things - implement VMNotify, and
> re-optimise VT-x to not intercept #DB/#AC by default.
>
> The second part is buggy in multiple ways. Both GDBSX and Introspection
> need
> to conditionally intercept #DB, which was not accounted for. Also, #DB
> interception has nothing at all to do with cpu_has_monitor_trap_flag.
>
> Revert the second half, leaving #DB/#AC intercepted unilaterally, but with
> VMNotify active by default when available.
>
> Fixes: 573279cde1c4 ("x86/vmx: implement Notify VM Exit")
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
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