linux-kernel - [PATCH v3 06/11] x86/xen: use capabilities instead of fake cpuid values for acpi

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Date:   Tue, 18 Apr 2017 08:31:14 +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 06/11] x86/xen: use capabilities instead of fake cpuid values for acpi

When running as pv domain xen_cpuid() is being used instead of
native_cpuid(). In xen_cpuid() the acpi feature is indicated as not
being present by special casing the related cpuid leaf in case we
are not the initial domain.

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

Signed-off-by: Juergen Gross <jgross@...e.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
---
 arch/x86/xen/enlighten_pv.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 53fe97bd720f..3196961862bc 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -165,7 +165,6 @@ xen_running_on_version_or_later(unsigned int major, unsigned int minor)
 	return false;
 }
 
-static __read_mostly unsigned int cpuid_leaf1_edx_mask = ~0;
 static __read_mostly unsigned int cpuid_leaf1_ecx_mask = ~0;
 
 static __read_mostly unsigned int cpuid_leaf1_ecx_set_mask;
@@ -177,7 +176,6 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
 {
 	unsigned maskebx = ~0;
 	unsigned maskecx = ~0;
-	unsigned maskedx = ~0;
 	unsigned setecx = 0;
 	/*
 	 * Mask out inconvenient features, to try and disable as many
@@ -187,7 +185,6 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
 	case 1:
 		maskecx = cpuid_leaf1_ecx_mask;
 		setecx = cpuid_leaf1_ecx_set_mask;
-		maskedx = cpuid_leaf1_edx_mask;
 		break;
 
 	case CPUID_MWAIT_LEAF:
@@ -214,7 +211,6 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
 	*bx &= maskebx;
 	*cx &= maskecx;
 	*cx |= setecx;
-	*dx &= maskedx;
 }
 STACK_FRAME_NON_STANDARD(xen_cpuid); /* XEN_EMULATE_PREFIX */
 
@@ -294,10 +290,6 @@ static void __init xen_init_cpuid_mask(void)
 	unsigned int ax, bx, cx, dx;
 	unsigned int xsave_mask;
 
-	if (!xen_initial_domain())
-		cpuid_leaf1_edx_mask &=
-			~((1 << X86_FEATURE_ACPI));  /* disable ACPI */
-
 	cpuid_leaf1_ecx_mask &= ~(1 << (X86_FEATURE_X2APIC % 32));
 
 	ax = 1;
@@ -323,6 +315,9 @@ static void __init xen_init_capabilities(void)
 	setup_clear_cpu_cap(X86_FEATURE_APERFMPERF);
 	setup_clear_cpu_cap(X86_FEATURE_MTRR);
 	setup_clear_cpu_cap(X86_FEATURE_ACC);
+
+	if (!xen_initial_domain())
+		setup_clear_cpu_cap(X86_FEATURE_ACPI);
 }
 
 static void xen_set_debugreg(int reg, unsigned long val)
-- 
2.12.0