From: Jeremy Fitzhardinge <jeremy@goop.org>
Date: Mon, 26 May 2008 22:31:04 +0000 (+0100)
Subject: xen: allow some cr4 updates
X-Git-Tag: firefly_0821_release~19697^2~253^24~41
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2956a3511c8c5dccb1d4739ead17c7c3c23a24b7;p=firefly-linux-kernel-4.4.55.git

xen: allow some cr4 updates

The guest can legitimately change things like cr4.OSFXSR and
OSXMMEXCPT, so let it.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 35ddaf50180a..f6876485ee7d 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -648,8 +648,10 @@ static unsigned long xen_read_cr2_direct(void)
 
 static void xen_write_cr4(unsigned long cr4)
 {
-	/* Just ignore cr4 changes; Xen doesn't allow us to do
-	   anything anyway. */
+	cr4 &= ~X86_CR4_PGE;
+	cr4 &= ~X86_CR4_PSE;
+
+	native_write_cr4(cr4);
 }
 
 static unsigned long xen_read_cr3(void)