linux-kernel - [PATCH 3.16 118/131] x86/speculation/l1tf: Protect NUMA-balance entries against L1TF

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Date:   Sat, 29 Sep 2018 22:43:07 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Mel Gorman" <mgorman@...e.de>,
        x86@...nel.org
Subject: [PATCH 3.16 118/131] x86/speculation/l1tf: Protect NUMA-balance
 entries against L1TF

3.16.59-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ben Hutchings <ben@...adent.org.uk>

NUMA balancing has its own functions that manipulated the PRESENT flag
in PTEs and PMDs.  These were not affected by the changes in commit
6b28baca9b1f "x86/speculation/l1tf: Protect PROT_NONE PTEs against
speculation".

This is not a problem upstream because NUMA balancing was changed to
use {pte,pmd}_modify() in Linux 4.0.

Override the generic implementations for x86 with implementations
that do the same inversion as {pte,pmd}_modify().

Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Cc: x86@...nel.org
Cc: Mel Gorman <mgorman@...e.de>
---
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -419,6 +419,54 @@ static inline pmd_t pmd_modify(pmd_t pmd
 	return __pmd(val);
 }
 
+#ifdef CONFIG_NUMA_BALANCING
+
+static inline pte_t pte_mknonnuma(pte_t pte)
+{
+	pteval_t val = pte_val(pte), oldval = val;
+
+	val &= ~_PAGE_NUMA;
+	val |= (_PAGE_PRESENT|_PAGE_ACCESSED);
+	val = flip_protnone_guard(oldval, val, PTE_PFN_MASK);
+	return __pte(val);
+}
+#define pte_mknonnuma pte_mknonnuma
+
+static inline pte_t pte_mknuma(pte_t pte)
+{
+	pteval_t val = pte_val(pte), oldval = val;
+
+	val &= ~_PAGE_PRESENT;
+	val |= _PAGE_NUMA;
+	val = flip_protnone_guard(oldval, val, PTE_PFN_MASK);
+	return __pte(val);
+}
+#define pte_mknuma pte_mknuma
+
+static inline pmd_t pmd_mknonnuma(pmd_t pmd)
+{
+	pmdval_t val = pmd_val(pmd), oldval = val;
+
+	val &= ~_PAGE_NUMA;
+	val |= (_PAGE_PRESENT|_PAGE_ACCESSED);
+	val = flip_protnone_guard(oldval, val, PTE_PFN_MASK);
+	return __pmd(val);
+}
+#define pmd_mknonnuma pmd_mknonnuma
+
+static inline pmd_t pmd_mknuma(pmd_t pmd)
+{
+	pmdval_t val = pmd_val(pmd), oldval = val;
+
+	val &= ~_PAGE_PRESENT;
+	val |= _PAGE_NUMA;
+	val = flip_protnone_guard(oldval, val, PTE_PFN_MASK);
+	return __pmd(val);
+}
+#define pmd_mknuma pmd_mknuma
+
+#endif /* CONFIG_NUMA_BALANCING */
+
 /* mprotect needs to preserve PAT bits when updating vm_page_prot */
 #define pgprot_modify pgprot_modify
 static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)