linux-kernel - [Question-kvm] Can hva_to_pfn_fast be executed in interrupt context?

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Message-ID: <20190813191435.GB10228@bharath12345-Inspiron-5559>
Date:   Wed, 14 Aug 2019 00:44:35 +0530
From:   Bharath Vedartham <linux.bhar@...il.com>
To:     pbonzini@...hat.com, rkrcmar@...hat.com
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, khalid.aziz@...cle.com
Subject: [Question-kvm] Can hva_to_pfn_fast be executed in interrupt context?

Hi all,

I was looking at the function hva_to_pfn_fast(in virt/kvm/kvm_main) which is 
executed in an atomic context(even in non-atomic context, since
hva_to_pfn_fast is much faster than hva_to_pfn_slow).

My question is can this be executed in an interrupt context? 

The motivation for this question is that in an interrupt context, we cannot
assume "current" to be the task_struct of the process of interest.
__get_user_pages_fast assume current->mm when walking the process page
tables. 

So if this function hva_to_pfn_fast can be executed in an
interrupt context, it would not be safe to retrive the pfn with
__get_user_pages_fast. 

Thoughts on this?

Thank you
Bharath