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From:   "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To:     Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Tom Lendacky <thomas.lendacky@amd.com>
Cc:     Dave Hansen <dave.hansen@intel.com>,
        Kai Huang <kai.huang@linux.intel.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: [PATCHv5 03/19] mm/ksm: Do not merge pages with different KeyIDs
Date:   Tue, 17 Jul 2018 14:20:13 +0300
Message-Id: <20180717112029.42378-4-kirill.shutemov@linux.intel.com>
In-Reply-To: <20180717112029.42378-1-kirill.shutemov@linux.intel.com>
References: <20180717112029.42378-1-kirill.shutemov@linux.intel.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Pages encrypted with different encryption keys are not allowed to be
merged by KSM. Otherwise it would cross security boundary.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/mm.h | 7 +++++++
 mm/ksm.c           | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 151d6e6b16e5..a4ce26aa0b65 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1551,6 +1551,13 @@ static inline int vma_keyid(struct vm_area_struct *vma)
 }
 #endif
 
+#ifndef page_keyid
+static inline int page_keyid(struct page *page)
+{
+	return 0;
+}
+#endif
+
 #ifdef CONFIG_SHMEM
 /*
  * The vma_is_shmem is not inline because it is used only by slow
diff --git a/mm/ksm.c b/mm/ksm.c
index a6d43cf9a982..1bd7b9710e29 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1214,6 +1214,9 @@ static int try_to_merge_one_page(struct vm_area_struct *vma,
 	if (!PageAnon(page))
 		goto out;
 
+	if (page_keyid(page) != page_keyid(kpage))
+		goto out;
+
 	/*
 	 * We need the page lock to read a stable PageSwapCache in
 	 * write_protect_page().  We use trylock_page() instead of
-- 
2.18.0