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Re: [RFC PATCH 1/4] x86/ept: Drop shadow mode check in ept_sync_domain()
- To: Teddy Astie <teddy.astie@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Thu, 27 Nov 2025 14:50:59 +0100
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Thu, 27 Nov 2025 13:51:20 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 27.11.2025 14:39, Teddy Astie wrote:
> This function can only be reached from EPT-related code which is inherently
> HAP. Thus it is not useful to check for shadow_paging (or lack of HAP) there.
>
> Moreover, it is an error to call this function in the non-EPT cases.
>
> Not a functional change.
>
> Signed-off-by: Teddy Astie <teddy.astie@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> This function is only called through EPT code and by vmx_domain_update_eptp()
> called by EPT log-dirty logic, and doesn't look reachable from shadow paging
> code.
>
> I think the original reason of this check was for eventually allowing guests
> to
> use both shadow paging and HAP and switch between the 2 dynamically.
I don't think there ever was such a plan. The function originally lived in
vmx.c,
and there - even if just as a safeguard - having the extra check may have made
sense.
Jan
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