linux-kernel - [PATCH v2 04/11] x86/xen: use capabilities instead of fake cpuid values for mtrr

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Message-Id: <20170413101116.723-5-jgross@suse.com>
Date:   Thu, 13 Apr 2017 12:11:09 +0200
From:   Juergen Gross <jgross@...e.com>
To:     linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org
Cc:     boris.ostrovsky@...cle.com, Juergen Gross <jgross@...e.com>
Subject: [PATCH v2 04/11] x86/xen: use capabilities instead of fake cpuid values for mtrr

When running as pv domain xen_cpuid() is being used instead of
native_cpuid(). In xen_cpuid() the mtrr feature is indicated as not
being present by special casing the related cpuid leaf.

Instead of delivering fake cpuid values clear the cpu capability bit
for mtrr instead.

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 arch/x86/xen/enlighten_pv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 4c8cd7278189..37e174d9009b 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -295,8 +295,7 @@ static void __init xen_init_cpuid_mask(void)
 	unsigned int xsave_mask;
 
 	cpuid_leaf1_edx_mask =
-		~((1 << X86_FEATURE_MTRR) |  /* disable MTRR */
-		  (1 << X86_FEATURE_ACC));   /* thermal monitoring */
+		~(1 << X86_FEATURE_ACC);   /* thermal monitoring */
 
 	if (!xen_initial_domain())
 		cpuid_leaf1_edx_mask &=
@@ -325,6 +324,7 @@ static void __init xen_init_capabilities(void)
 	setup_force_cpu_cap(X86_FEATURE_XENPV);
 	setup_clear_cpu_cap(X86_FEATURE_DCA);
 	setup_clear_cpu_cap(X86_FEATURE_APERFMPERF);
+	setup_clear_cpu_cap(X86_FEATURE_MTRR);
 }
 
 static void xen_set_debugreg(int reg, unsigned long val)
-- 
2.12.0