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Date:      Tue, 4 Dec 2012 00:51:30 +0000 (UTC)
From:      Konstantin Belousov <kib@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org
Subject:   svn commit: r243848 - stable/9/sys/amd64/amd64
Message-ID:  <201212040051.qB40pUZG001173@svn.freebsd.org>
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Author: kib
Date: Tue Dec  4 00:51:29 2012
New Revision: 243848
URL: http://svnweb.freebsd.org/changeset/base/243848

Log:
  MFC r242433:
  Enable the new instructions for reading and writing bases for %fs,
  %gs, when supported. Enable SMEP when supported.
  
  MFC r242828:
  Do not try to enable new features in the %cr4 if running under hypervisor.

Modified:
  stable/9/sys/amd64/amd64/identcpu.c
  stable/9/sys/amd64/amd64/initcpu.c
  stable/9/sys/amd64/amd64/pmap.c
Directory Properties:
  stable/9/sys/   (props changed)

Modified: stable/9/sys/amd64/amd64/identcpu.c
==============================================================================
--- stable/9/sys/amd64/amd64/identcpu.c	Tue Dec  4 00:44:31 2012	(r243847)
+++ stable/9/sys/amd64/amd64/identcpu.c	Tue Dec  4 00:51:29 2012	(r243848)
@@ -481,7 +481,7 @@ SYSINIT(hook_tsc_freq, SI_SUB_CONFIGURE,
 void
 identify_cpu(void)
 {
-	u_int regs[4];
+	u_int regs[4], cpu_stdext_disable;
 
 	do_cpuid(0, regs);
 	cpu_high = regs[0];
@@ -516,6 +516,20 @@ identify_cpu(void)
 	if (cpu_high >= 7) {
 		cpuid_count(7, 0, regs);
 		cpu_stdext_feature = regs[1];
+
+		/*
+		 * Some hypervisors fail to filter out unsupported
+		 * extended features.  For now, disable the
+		 * extensions, activation of which requires setting a
+		 * bit in CR4, and which VM monitors do not support.
+		 */
+		if (cpu_feature2 & CPUID2_HV) {
+			cpu_stdext_disable = CPUID_STDEXT_FSGSBASE |
+			    CPUID_STDEXT_SMEP;
+		} else
+			cpu_stdext_disable = 0;
+		TUNABLE_INT_FETCH("hw.cpu_stdext_disable", &cpu_stdext_disable);
+		cpu_stdext_feature &= ~cpu_stdext_disable;
 	}
 
 	if (cpu_vendor_id == CPU_VENDOR_INTEL ||

Modified: stable/9/sys/amd64/amd64/initcpu.c
==============================================================================
--- stable/9/sys/amd64/amd64/initcpu.c	Tue Dec  4 00:44:31 2012	(r243847)
+++ stable/9/sys/amd64/amd64/initcpu.c	Tue Dec  4 00:51:29 2012	(r243848)
@@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
+#include <sys/pcpu.h>
 #include <sys/systm.h>
 #include <sys/sysctl.h>
 
@@ -153,11 +154,25 @@ void
 initializecpu(void)
 {
 	uint64_t msr;
+	uint32_t cr4;
 
+	cr4 = rcr4();
 	if ((cpu_feature & CPUID_XMM) && (cpu_feature & CPUID_FXSR)) {
-		load_cr4(rcr4() | CR4_FXSR | CR4_XMM);
+		cr4 |= CR4_FXSR | CR4_XMM;
 		cpu_fxsr = hw_instruction_sse = 1;
 	}
+	if (cpu_stdext_feature & CPUID_STDEXT_FSGSBASE)
+		cr4 |= CR4_FSGSBASE;
+
+	/*
+	 * Postpone enabling the SMEP on the boot CPU until the page
+	 * tables are switched from the boot loader identity mapping
+	 * to the kernel tables.  The boot loader enables the U bit in
+	 * its tables.
+	 */
+	if (!IS_BSP() && (cpu_stdext_feature & CPUID_STDEXT_SMEP))
+		cr4 |= CR4_SMEP;
+	load_cr4(cr4);
 	if ((amd_feature & AMDID_NX) != 0) {
 		msr = rdmsr(MSR_EFER) | EFER_NXE;
 		wrmsr(MSR_EFER, msr);

Modified: stable/9/sys/amd64/amd64/pmap.c
==============================================================================
--- stable/9/sys/amd64/amd64/pmap.c	Tue Dec  4 00:44:31 2012	(r243847)
+++ stable/9/sys/amd64/amd64/pmap.c	Tue Dec  4 00:51:29 2012	(r243848)
@@ -629,6 +629,8 @@ pmap_bootstrap(vm_paddr_t *firstaddr)
 	/* XXX do %cr0 as well */
 	load_cr4(rcr4() | CR4_PGE | CR4_PSE);
 	load_cr3(KPML4phys);
+	if (cpu_stdext_feature & CPUID_STDEXT_SMEP)
+		load_cr4(rcr4() | CR4_SMEP);
 
 	/*
 	 * Initialize the kernel pmap (which is statically allocated).

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