linux-kernel - [PATCHv4 05/18] mm/khugepaged: Handle encrypted pages

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Date:   Tue, 26 Jun 2018 17:22:32 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Tom Lendacky <thomas.lendacky@....com>
Cc:     Dave Hansen <dave.hansen@...el.com>,
        Kai Huang <kai.huang@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv4 05/18] mm/khugepaged: Handle encrypted pages

khugepaged allocates page in advance, before we found a VMA for
collapse. We don't yet know which KeyID to use for the allocation.

The page is allocated with KeyID-0. Once we know that the VMA is
suitable for collapsing, we prepare the page for KeyID we need, based on
vma_keyid().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 mm/khugepaged.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index d7b2a4bf8671..4dff3c114501 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1056,6 +1056,16 @@ static void collapse_huge_page(struct mm_struct *mm,
 	 */
 	anon_vma_unlock_write(vma->anon_vma);
 
+	/*
+	 * At this point new_page is allocated as non-encrypted.
+	 * If VMA's KeyID is non-zero, we need to prepare it to be encrypted
+	 * before coping data.
+	 */
+	if (vma_keyid(vma)) {
+		prep_encrypted_page(new_page, HPAGE_PMD_ORDER,
+				vma_keyid(vma), false);
+	}
+
 	__collapse_huge_page_copy(pte, new_page, vma, address, pte_ptl);
 	pte_unmap(pte);
 	__SetPageUptodate(new_page);
-- 
2.18.0