linux-kernel - Re: [PATCH] mm: Export follow_pte() for KVM so that KVM can stop using follow

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Date:   Thu, 4 Feb 2021 18:19:13 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        David Stevens <stevensd@...gle.com>,
        Jann Horn <jannh@...gle.com>, Jason Gunthorpe <jgg@...pe.ca>,
        kvm@...r.kernel.org
Subject: Re: [PATCH] mm: Export follow_pte() for KVM so that KVM can stop
 using follow_pfn()

On 04/02/21 18:16, Sean Christopherson wrote:
> Export follow_pte() to fix build breakage when KVM is built as a module.
> An in-flight KVM fix switches from follow_pfn() to follow_pte() in order
> to grab the page protections along with the PFN.
> 
> Fixes: bd2fae8da794 ("KVM: do not assume PTE is writable after follow_pfn")
> Cc: David Stevens <stevensd@...gle.com>
> Cc: Jann Horn <jannh@...gle.com>
> Cc: Jason Gunthorpe <jgg@...pe.ca>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: kvm@...r.kernel.org
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
> 
> Paolo, maybe you can squash this with the appropriate acks?

Indeed, you beat me by a minute.  This change is why I hadn't sent out 
the patch yet.

Andrew or Jason, ok to squash this?

Paolo

>   mm/memory.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index feff48e1465a..15cbd10afd59 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4775,6 +4775,7 @@ int follow_pte(struct mm_struct *mm, unsigned long address,
>   out:
>   	return -EINVAL;
>   }
> +EXPORT_SYMBOL_GPL(follow_pte);
>   
>   /**
>    * follow_pfn - look up PFN at a user virtual address
>