svn commit: r210774 - in head/sys: amd64/amd64 i386/i386

[John Baldwin]

Author: jhb
Date: Mon Aug  2 17:01:23 2010
New Revision: 210774
URL: http://svn.freebsd.org/changeset/base/210774

Log:
  Tweak the logic to disable CLFLUSH in virtual environments to work around
  problems with flushing the local APIC register range so that it checks
  vm_guest directly.
  
  Reviewed by:	kib, alc
  MFC after:	2 weeks

Modified:
  head/sys/amd64/amd64/initcpu.c
  head/sys/i386/i386/initcpu.c

Modified: head/sys/amd64/amd64/initcpu.c
==============================================================================
--- head/sys/amd64/amd64/initcpu.c	Mon Aug  2 16:18:41 2010	(r210773)
+++ head/sys/amd64/amd64/initcpu.c	Mon Aug  2 17:01:23 2010	(r210774)
@@ -177,17 +177,17 @@ initializecpucache()
 	if ((cpu_feature & CPUID_CLFSH) != 0)
 		cpu_clflush_line_size = ((cpu_procinfo >> 8) & 0xff) * 8;
 	/*
-	 * XXXKIB: (temporary) hack to work around traps generated when
-	 * CLFLUSHing APIC registers window.
+	 * XXXKIB: (temporary) hack to work around traps generated
+	 * when CLFLUSHing APIC register window under virtualization
+	 * environments.  These environments tend to disable the
+	 * CPUID_SS feature even though the native CPU supports it.
 	 */
 	TUNABLE_INT_FETCH("hw.clflush_disable", &hw_clflush_disable);
-	if (cpu_vendor_id == CPU_VENDOR_INTEL && !(cpu_feature & CPUID_SS) &&
-	    hw_clflush_disable == -1)
+	if (vm_guest != VM_GUEST_NO && hw_clflush_disable == -1)
 		cpu_feature &= ~CPUID_CLFSH;
 	/*
 	 * Allow to disable CLFLUSH feature manually by
-	 * hw.clflush_disable tunable.  This may help Xen guest on some AMD
-	 * CPUs.
+	 * hw.clflush_disable tunable.
 	 */
 	if (hw_clflush_disable == 1)
 		cpu_feature &= ~CPUID_CLFSH;

Modified: head/sys/i386/i386/initcpu.c
==============================================================================
--- head/sys/i386/i386/initcpu.c	Mon Aug  2 16:18:41 2010	(r210773)
+++ head/sys/i386/i386/initcpu.c	Mon Aug  2 17:01:23 2010	(r210774)
@@ -724,17 +724,17 @@ initializecpu(void)
 	if ((cpu_feature & CPUID_CLFSH) != 0)
 		cpu_clflush_line_size = ((cpu_procinfo >> 8) & 0xff) * 8;
 	/*
-	 * XXXKIB: (temporary) hack to work around traps generated when
-	 * CLFLUSHing APIC registers window.
+	 * XXXKIB: (temporary) hack to work around traps generated
+	 * when CLFLUSHing APIC register window under virtualization
+	 * environments.  These environments tend to disable the
+	 * CPUID_SS feature even though the native CPU supports it.
 	 */
 	TUNABLE_INT_FETCH("hw.clflush_disable", &hw_clflush_disable);
-	if (cpu_vendor_id == CPU_VENDOR_INTEL && !(cpu_feature & CPUID_SS) &&
-	    hw_clflush_disable == -1)
+	if (vm_guest != VM_GUEST_NO && hw_clflush_disable == -1)
 		cpu_feature &= ~CPUID_CLFSH;
 	/*
 	 * Allow to disable CLFLUSH feature manually by
-	 * hw.clflush_disable tunable.  This may help Xen guest on some AMD
-	 * CPUs.
+	 * hw.clflush_disable tunable.
 	 */
 	if (hw_clflush_disable == 1)
 		cpu_feature &= ~CPUID_CLFSH;