linux-kernel - [PATCH v7 7/7] xen/x86: Don't try to set PCE bit in CR4

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Date:	Mon, 10 Aug 2015 16:34:38 -0400
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	david.vrabel@...rix.com, konrad.wilk@...cle.com
Cc:	kevin.tian@...el.com, jbeulich@...e.com,
	dietmar.hahn@...fujitsu.com, stefano.stabellini@...citrix.com,
	julien.grall@...rix.com, xen-devel@...ts.xen.org,
	linux-kernel@...r.kernel.org, boris.ostrovsky@...cle.com
Subject: [PATCH v7 7/7] xen/x86: Don't try to set PCE bit in CR4

Since VPMU code emulates RDPMC instruction with RDMSR and because hypervisor
does not emulate it there is no reason to try setting CR4's PCE bit (and the
hypervisor will warn on seeing it set).

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
---
 arch/x86/xen/enlighten.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 623f8ad..d9e12e3 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -971,8 +971,7 @@ static void xen_write_cr0(unsigned long cr0)
 
 static void xen_write_cr4(unsigned long cr4)
 {
-	cr4 &= ~X86_CR4_PGE;
-	cr4 &= ~X86_CR4_PSE;
+	cr4 &= ~(X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PCE);
 
 	native_write_cr4(cr4);
 }
-- 
1.8.1.4

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