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Date:   Wed, 4 Aug 2021 14:38:35 +0200
From:   Joerg Roedel <jroedel@suse.de>
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     kvm@vger.kernel.org
Subject: Re: [bug report] x86/sev: Split up runtime #VC handler for correct
 state tracking
Message-ID: <YQqKS7ayK1qkmNzv@suse.de>
References: <20210804095725.GA8011@kili>
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Hi Dan,

On Wed, Aug 04, 2021 at 12:57:25PM +0300, Dan Carpenter wrote:
> These sleeping in atomic static checker warnings come with a lot of
> caveats because the call tree is very long and it's easy to have false
> positives.
> 
> --> vc_raw_handle_exception()
>     --> vc_forward_exception()
>         --> exc_page_fault()
> 
> Page faults always sleep right?

No, page faults do no always sleep, only when IO needs to be done to
fulfill the page fault request. In this case, the page-fault handler
will never sleep, because it is called with preemption disabled. The
page-fault handler can detect this and just do nothing. The #VC handler
will return for re-fault in this case.

Hope that helps,

     Joerg