linux-kernel - [PATCH] xen: remove global bit from __default_kernel_pte

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Date:   Mon,  2 Jul 2018 12:00:18 +0200
From:   Juergen Gross <jgross@...e.com>
To:     linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
        x86@...nel.org
Cc:     boris.ostrovsky@...cle.com, hpa@...or.com, tglx@...utronix.de,
        mingo@...hat.com, Juergen Gross <jgross@...e.com>,
        stable@...r.kernel.org
Subject: [PATCH] xen: remove global bit from __default_kernel_pte_mask for pv guests

When removing the global bit from __supported_pte_mask do the same for
__default_kernel_pte_mask in order to avoid the WARN_ONCE() in
check_pgprot() when setting a kernel pte before having called
init_mem_mapping().

Cc: <stable@...r.kernel.org> # 4.17
Reported-by: Michael Young <m.a.young@...ham.ac.uk>
Signed-off-by: Juergen Gross <jgross@...e.com>
---
 arch/x86/xen/enlighten_pv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 0f4cd9e5bed4..cf7b13d3e911 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -1230,6 +1230,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
 
 	/* Prevent unwanted bits from being set in PTEs. */
 	__supported_pte_mask &= ~_PAGE_GLOBAL;
+	__default_kernel_pte_mask &= ~_PAGE_GLOBAL;
 
 	/*
 	 * Prevent page tables from being allocated in highmem, even
-- 
2.13.7