Re: [PATCH] xen/arm: Reduce redundant clear root pages when teardown p2m

[Julien Grall]

On 12/12/2022 11:27, Henry Wang wrote:

Hi Julien,

Hi,

-----Original Message-----
From: Julien Grall <jul...@xen.org>
Subject: Re: [PATCH] xen/arm: Reduce redundant clear root pages when
teardown p2m

Hi Henry,

       PROGRESS(p2m):
+        /*
+         * We are about to free the intermediate page-tables, so clear the
+         * root to prevent any walk to use them.
+         */
+        p2m_clear_root_pages(&d->arch.p2m);

The commit message suggests this should only be called once. However,
you will still end up to call p2m_clear_root_pages() multiple time if
p2m_teardown() is preempted.

Thanks for confirming this, would adding another PROGRESS stage
such as PROGRESS(p2m_clean) before PROGRESS(p2m) seem ok to you?

The would be fine with me.

Cheers,

--
Julien Grall