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;
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