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

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Message-Id: <20210204171619.3640084-1-seanjc@google.com>
Date:   Thu,  4 Feb 2021 09:16:19 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     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>,
        Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH] mm: Export follow_pte() for KVM so that KVM can stop using follow_pfn()

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?

 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
-- 
2.30.0.365.g02bc693789-goog