linux-kernel - [PATCH v3 03/11] x86/xen: use capabilities instead of fake cpuid values for aperf

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Message-Id: <20170418063119.11654-4-jgross@suse.com>
Date:   Tue, 18 Apr 2017 08:31:11 +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 v3 03/11] x86/xen: use capabilities instead of fake cpuid values for aperf

When running as pv domain xen_cpuid() is being used instead of
native_cpuid(). In xen_cpuid() the aperf/mperf 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 aperf/mperf instead.

Signed-off-by: Juergen Gross <jgross@...e.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
---
 arch/x86/xen/enlighten_pv.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index bd69868909b4..4c8cd7278189 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -165,9 +165,6 @@ xen_running_on_version_or_later(unsigned int major, unsigned int minor)
 	return false;
 }
 
-#define CPUID_THERM_POWER_LEAF 6
-#define APERFMPERF_PRESENT 0
-
 static __read_mostly unsigned int cpuid_leaf1_edx_mask = ~0;
 static __read_mostly unsigned int cpuid_leaf1_ecx_mask = ~0;
 
@@ -201,11 +198,6 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
 		*dx = cpuid_leaf5_edx_val;
 		return;
 
-	case CPUID_THERM_POWER_LEAF:
-		/* Disabling APERFMPERF for kernel usage */
-		maskecx = ~(1 << APERFMPERF_PRESENT);
-		break;
-
 	case 0xb:
 		/* Suppress extended topology stuff */
 		maskebx = 0;
@@ -332,6 +324,7 @@ static void __init xen_init_capabilities(void)
 	setup_clear_cpu_cap(X86_BUG_SYSRET_SS_ATTRS);
 	setup_force_cpu_cap(X86_FEATURE_XENPV);
 	setup_clear_cpu_cap(X86_FEATURE_DCA);
+	setup_clear_cpu_cap(X86_FEATURE_APERFMPERF);
 }
 
 static void xen_set_debugreg(int reg, unsigned long val)
-- 
2.12.0