From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Wed, 18 Nov 2015 11:43:01 +0000 (+0000)
Subject: xen/x86: Improve disabling of features which have dependencies
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~1307
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=33d0d39b3b1b78b25a4590d6c723cdf4d24acd91;p=xen.git

xen/x86: Improve disabling of features which have dependencies

APIC and XSAVE have dependent features, which also need disabling if Xen
chooses to disable a feature.

Use setup_clear_cpu_cap() rather than clear_bit(), as it takes care of
dependent features as well.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <JBeulich@suse.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---

diff --git a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c
index b9601adeec..8df5bd35fa 100644
--- a/xen/arch/x86/apic.c
+++ b/xen/arch/x86/apic.c
@@ -1349,7 +1349,7 @@ void pmu_apic_interrupt(struct cpu_user_regs *regs)
 int __init APIC_init_uniprocessor (void)
 {
     if (enable_local_apic < 0)
-        __clear_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);
+        setup_clear_cpu_cap(X86_FEATURE_APIC);
 
     if (!smp_found_config && !cpu_has_apic) {
         skip_ioapic_setup = 1;
diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index 0942b44bfd..b5c023f743 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -16,9 +16,6 @@
 
 #include "cpu.h"
 
-static bool_t use_xsave = 1;
-boolean_param("xsave", use_xsave);
-
 bool_t opt_arat = 1;
 boolean_param("arat", opt_arat);
 
@@ -341,12 +338,6 @@ void identify_cpu(struct cpuinfo_x86 *c)
 	if (this_cpu->c_init)
 		this_cpu->c_init(c);
 
-        /* Initialize xsave/xrstor features */
-	if ( !use_xsave )
-		__clear_bit(X86_FEATURE_XSAVE, boot_cpu_data.x86_capability);
-
-	if ( cpu_has_xsave )
-		xstate_init(c);
 
    	if ( !opt_pku )
 		setup_clear_cpu_cap(X86_FEATURE_PKU);
@@ -370,6 +361,9 @@ void identify_cpu(struct cpuinfo_x86 *c)
 
 	/* Now the feature flags better reflect actual CPU features! */
 
+	if ( cpu_has_xsave )
+		xstate_init(c);
+
 #ifdef NOISY_CAPS
 	printk(KERN_DEBUG "CPU: After all inits, caps:");
 	for (i = 0; i < NCAPINTS; i++)
diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c
index 48c01957b8..83597223fc 100644
--- a/xen/arch/x86/xstate.c
+++ b/xen/arch/x86/xstate.c
@@ -533,11 +533,15 @@ unsigned int xstate_ctxt_size(u64 xcr0)
 /* Collect the information of processor's extended state */
 void xstate_init(struct cpuinfo_x86 *c)
 {
+    static bool_t __initdata use_xsave = 1;
+    boolean_param("xsave", use_xsave);
+
     bool_t bsp = c == &boot_cpu_data;
     u32 eax, ebx, ecx, edx;
     u64 feature_mask;
 
-    if ( boot_cpu_data.cpuid_level < XSTATE_CPUID )
+    if ( (bsp && !use_xsave) ||
+         boot_cpu_data.cpuid_level < XSTATE_CPUID )
     {
         BUG_ON(!bsp);
         setup_clear_cpu_cap(X86_FEATURE_XSAVE);