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Date:      Fri, 27 Aug 2010 18:55:48 +0000 (UTC)
From:      John Baldwin <jhb@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-7@freebsd.org
Subject:   svn commit: r211892 - in stable/7/sys: amd64/amd64 i386/i386 kern
Message-ID:  <201008271855.o7RItmVS003972@svn.freebsd.org>
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Author: jhb
Date: Fri Aug 27 18:55:48 2010
New Revision: 211892
URL: http://svn.freebsd.org/changeset/base/211892

Log:
  MFC 210774,210935:
  - 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.
  - Add Xen to the list of virtual vendors.  In the non PV (HVM) case this
    fixes the virtualization detection successfully disabling the CLFLUSH
    instruction.

Modified:
  stable/7/sys/amd64/amd64/initcpu.c
  stable/7/sys/i386/i386/initcpu.c
  stable/7/sys/kern/subr_param.c
Directory Properties:
  stable/7/sys/   (props changed)
  stable/7/sys/cddl/contrib/opensolaris/   (props changed)
  stable/7/sys/contrib/dev/acpica/   (props changed)
  stable/7/sys/contrib/pf/   (props changed)

Modified: stable/7/sys/amd64/amd64/initcpu.c
==============================================================================
--- stable/7/sys/amd64/amd64/initcpu.c	Fri Aug 27 18:55:24 2010	(r211891)
+++ stable/7/sys/amd64/amd64/initcpu.c	Fri Aug 27 18:55:48 2010	(r211892)
@@ -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: stable/7/sys/i386/i386/initcpu.c
==============================================================================
--- stable/7/sys/i386/i386/initcpu.c	Fri Aug 27 18:55:24 2010	(r211891)
+++ stable/7/sys/i386/i386/initcpu.c	Fri Aug 27 18:55:48 2010	(r211892)
@@ -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;

Modified: stable/7/sys/kern/subr_param.c
==============================================================================
--- stable/7/sys/kern/subr_param.c	Fri Aug 27 18:55:24 2010	(r211891)
+++ stable/7/sys/kern/subr_param.c	Fri Aug 27 18:55:48 2010	(r211892)
@@ -145,6 +145,7 @@ static const char *const vm_bnames[] = {
 	"QEMU",				/* QEMU */
 	"Plex86",			/* Plex86 */
 	"Bochs",			/* Bochs */
+	"Xen",				/* Xen */
 	NULL
 };

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