Date: Tue, 23 Feb 2010 11:29:55 -0600 From: Alan Cox <alc@cs.rice.edu> To: freebsd-stable@freebsd.org Cc: alc@freebsd.org, Andriy Gapon <avg@icyb.net.ua>, Jeremy Chadwick <freebsd@jdc.parodius.com>, Ivan Voras <ivoras@freebsd.org> Subject: Re: Strange problem with 8-stable, VMWare vSphere 4 & AMD CPUs (unexpected shutdowns) Message-ID: <4B841093.2000402@cs.rice.edu> In-Reply-To: <4B744EB2.3070108@cs.rice.edu> References: <hkujop$hsa$1@ger.gmane.org> <4B72D94A.8030509@icyb.net.ua> <hkup1g$763$1@ger.gmane.org> <4B72E93C.80102@icyb.net.ua> <9bbcef731002101003r203f5189xf139700a0d48afa0@mail.gmail.com> <4B72F67F.4000209@icyb.net.ua> <9bbcef731002101026k5007075cqf97fc80404ac3fa7@mail.gmail.com> <4B72FC55.2090508@icyb.net.ua> <9bbcef731002101038r1ac04141t505216816489376f@mail.gmail.com> <20100210184623.GA78851@icarus.home.lan> <ca3526251002102037j21b11a7an572f397a9ae1eda0@mail.gmail.com> <4B741B7D.1030306@icyb.net.ua> <4B744EB2.3070108@cs.rice.edu>
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Alan Cox wrote:
> The next public revision guide from AMD will contain an errata (383)
> that documents the bug. However, it doesn't really tell us anything
> that we didn't already know.
Could someone on this list please test the attached patch in an amd64
FreeBSD 8 guest running on vSphere 4 with an AMD Family 10h processor
underneath? Before testing the patch, remove the manual setting of
vm.pmap.pg_ps_enabled="0" from /boot/loader.conf. After booting the
virtual machine, please run "sysctl vm.pmap.pg_ps_enabled" to verify
that superpage promotion has been automatically disabled.
Thanks,
Alan
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Index: amd64/amd64/pmap.c
===================================================================
--- amd64/amd64/pmap.c (revision 204175)
+++ amd64/amd64/pmap.c (working copy)
@@ -686,6 +686,15 @@ pmap_init(void)
pv_entry_high_water = 9 * (pv_entry_max / 10);
/*
+ * Disable large page mappings by default if the kernel is running in
+ * a virtual machine on an AMD Family 10h processor. This is a work-
+ * around for Erratum 383.
+ */
+ if (vm_guest == VM_GUEST_VM && cpu_vendor_id == CPU_VENDOR_AMD &&
+ CPUID_TO_FAMILY(cpu_id) == 0x10)
+ pg_ps_enabled = 0;
+
+ /*
* Are large page mappings enabled?
*/
TUNABLE_INT_FETCH("vm.pmap.pg_ps_enabled", &pg_ps_enabled);
Index: kern/subr_param.c
===================================================================
--- kern/subr_param.c (revision 204175)
+++ kern/subr_param.c (working copy)
@@ -74,10 +74,6 @@ __FBSDID("$FreeBSD$");
#define MAXFILES (maxproc * 2)
#endif
-/* Values of enum VM_GUEST members are used as indices in
- * vm_guest_sysctl_names */
-enum VM_GUEST { VM_GUEST_NO = 0, VM_GUEST_VM, VM_GUEST_XEN };
-
static int sysctl_kern_vm_guest(SYSCTL_HANDLER_ARGS);
int hz;
Index: sys/systm.h
===================================================================
--- sys/systm.h (revision 204175)
+++ sys/systm.h (working copy)
@@ -45,6 +45,10 @@
#include <sys/queue.h>
#include <sys/stdint.h> /* for people using printf mainly */
+/* Values of enum VM_GUEST members are used as indices in
+ * vm_guest_sysctl_names */
+enum VM_GUEST { VM_GUEST_NO = 0, VM_GUEST_VM, VM_GUEST_XEN };
+
extern int cold; /* nonzero if we are doing a cold boot */
extern int rebooting; /* boot() has been called. */
extern const char *panicstr; /* panic message */
@@ -63,6 +67,7 @@ extern int bootverbose; /* nonzero to print verbo
extern int maxusers; /* system tune hint */
extern int ngroups_max; /* max # of supplemental groups */
+extern int vm_guest; /* Running as virtual machine guest? */
#ifdef INVARIANTS /* The option is always available */
#define KASSERT(exp,msg) do { \
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