Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
patch_amd64errata.diff
Index: amd64/amd64/amd64errata.c
===
RCS file: /cvs/src/sys/arch/amd64/amd64/amd64errata.c,v
retrieving revision 1.3
diff -u -p -u -p -r1.3 amd64errata.c
--- amd64/amd64/amd64errata.c27 Mar 2012 05:59:46 -1.3
+++ amd64/amd64/amd64errata.c19 May 2013 23:48:11 -
@@ -293,6 +293,9 @@ amd64_errata(struct cpu_info *ci)
int found = 0;
int corrected = 0;
+if (ci-ci_feature_eflags CPUIDECX_RAZ)
+return;
+
CPUID(0x8001, code, dummy, dummy, dummy);
for (i = 0; ; i += 2) {
Index: amd64/amd64/identcpu.c
===
RCS file: /cvs/src/sys/arch/amd64/amd64/identcpu.c,v
retrieving revision 1.47
diff -u -p -u -p -r1.47 identcpu.c
--- amd64/amd64/identcpu.c6 May 2013 04:32:12 -1.47
+++ amd64/amd64/identcpu.c19 May 2013 23:48:11 -
@@ -129,6 +129,7 @@ const struct {
{ CPUIDECX_AVX,AVX },
{ CPUIDECX_F16C,F16C },
{ CPUIDECX_RDRAND,RDRAND },
+{ CPUIDECX_RAZ,RAZ }
}, cpu_ecpuid_ecxfeatures[] = {
{ CPUIDECX_LAHF,LAHF },
{ CPUIDECX_CMPLEG,CMPLEG },
Index: amd64/include/specialreg.h
===
RCS file: /cvs/src/sys/arch/amd64/include/specialreg.h,v
retrieving revision 1.25
diff -u -p -u -p -r1.25 specialreg.h
--- amd64/include/specialreg.h6 May 2013 04:32:12 -1.25
+++ amd64/include/specialreg.h19 May 2013 23:48:11 -
@@ -158,6 +158,7 @@
#defineCPUIDECX_AVX0x1000/* Advanced Vector Extensions */
#defineCPUIDECX_F16C0x2000/* 16bit fp conversion */
#defineCPUIDECX_RDRAND0x4000/* RDRAND instruction */
+#defineCPUIDECX_RAZ0x8000/* RAZ. Indicates guest state. */
/*
* Structured Extended Feature Flags Parameters (CPUID function 0x7,
leaf 0)
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
$ cat patch_amd64errata.diff
Index: amd64/amd64/amd64errata.c
===
RCS file: /cvs/src/sys/arch/amd64/amd64/amd64errata.c,v
retrieving revision 1.3
diff -u -p -u -p -r1.3 amd64errata.c
--- amd64/amd64/amd64errata.c27 Mar 2012 05:59:46 -1.3
+++ amd64/amd64/amd64errata.c19 May 2013 23:48:11 -
@@ -293,6 +293,9 @@ amd64_errata(struct cpu_info *ci)
int found = 0;
int corrected = 0;
+if (ci-ci_feature_eflags CPUIDECX_RAZ)
+return;
+
CPUID(0x8001, code, dummy, dummy, dummy);
for (i = 0; ; i += 2) {
Index: amd64/amd64/identcpu.c
===
RCS file: /cvs/src/sys/arch/amd64/amd64/identcpu.c,v
retrieving revision 1.47
diff -u -p -u -p -r1.47 identcpu.c
--- amd64/amd64/identcpu.c6 May 2013 04:32:12 -1.47
+++ amd64/amd64/identcpu.c19 May 2013 23:48:11 -
@@ -129,6 +129,7 @@ const struct {
{ CPUIDECX_AVX,AVX },
{ CPUIDECX_F16C,F16C },
{ CPUIDECX_RDRAND,RDRAND },
+{ CPUIDECX_RAZ,RAZ }
}, cpu_ecpuid_ecxfeatures[] = {
{ CPUIDECX_LAHF,LAHF },
{ CPUIDECX_CMPLEG,CMPLEG },
Index: amd64/include/specialreg.h
===
RCS file: /cvs/src/sys/arch/amd64/include/specialreg.h,v
retrieving revision 1.25
diff -u -p -u -p -r1.25 specialreg.h
--- amd64/include/specialreg.h6 May 2013 04:32:12 -1.25
+++ amd64/include/specialreg.h19 May 2013 23:48:11 -
@@ -158,6 +158,7 @@
#defineCPUIDECX_AVX0x1000/* Advanced Vector Extensions */
#defineCPUIDECX_F16C0x2000/* 16bit fp conversion */
#defineCPUIDECX_RDRAND0x4000/* RDRAND instruction */
+#defineCPUIDECX_RAZ0x8000/* RAZ. Indicates guest state. */
/*
* Structured Extended Feature Flags Parameters (CPUID function 0x7,
leaf 0)
2013/5/20 Roman Kravchuk kravchuk...@gmail.com
Hello bugs@,
I'm have problem with run OpenBSD current amd64 as guest in KVM hypervisor
on Ubuntu server with AMD CPU.
Host OS: Ubuntu 12.04 TLS
Host CPU: AMD Phenom(tm) II X4 975 Processor stepping 03
Host kernel: Linux M720-US3 3.2.0-43-generic #68-Ubuntu SMP Wed May 15
03:33:33 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
qemu-kvm: 1.2.0+dfsg-0~12.04~ppa0
seabios: 1.7.0-1
OpenBSD crash:
acpiprt0 at acpi0: bus 0 (PCI0)
mpbios0 at bios0: Intel MP Specification 1.4
cpu0 at mainbus0: apid 0 (boot processor)
cpu0: AMD Phenom(tm) 9550 Quad-Core Processor, 3600.53 MHz
cpu0:
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CF
LUSH,MMX,FXSR,SSE,SSE2,SSE3,CX16,POPCNT,NXE,MMXX,FFXSR,LONG,3DNOW2,3DNOW,LAHF,CM
PLEG,SVM,AMCR8,ABM,SSE4A,MASSE,3DNOWP
cpu0: 64KB 64b/line 2-way I-cache, 64KB 64b/line 2-way D-cache, 512KB
64b/line 1
6-way L2 cache
cpu0: ITLB 255 4KB entries direct-mapped, 255 4MB entries direct-mapped
cpu0: DTLB 255 4KB entries direct-mapped, 255 4MB entries direct-mapped
kernel: protection fault trap, code=0
Stopped at aesni_setup+0x1a0: rdmsr
aesni_setup() at aesni setup+0x1a0
amd64_errata() at amd64 errata+0xc9
identifycpu() at identifycpu+0x729
cpu attach() at cpu_attach+0x2ce
config_attach() at config_attach+0x1d4
mpbios_cpu() at mpbios_cpu+0x5b
mpbios_scan() at mpbios_scan+0x355
config_attach() at config_attach+0x1d4
bios_attach() at bios_attach+0x296
config_attach() at config_attach+0x1d4
end trace frame: 0x81de9e30, count: 0
ddb{0}
ddb{0} trace
aesni_setup() at aesni_setup+0x1a0
amd64_errata() at amd64_errata+0xc9
identifycpu() at identifycpu+0x729
cpu_attach() at cpu_attach+0x2ce
config_attach() at config_attach+0x1d4
mpbios_cpu() at mpbios_cpu+0x5b
mpbios_scan() at mpbios_scan+0x355
config_attach() at config_attach+0x1d4
bios_attach() at bios_attach+0x296
config_attach() at config_attach+0x1d4
mainbus_attach() at mainbus_attach+0x5b
config_attach() at config_attach+0x1d4
cpu_configure() at cpu_configure+0x17
main() at main+0x3f5
end trace frame: 0x0, count: -14
ddb{0}
ddb{0}ps
PID PPID PGRP UID S FLAGS WAIT COMMAND
*0 -10 0 7 0x200 swapper
ddb{0}
After ported and applied patch from NetBSD (
http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/arch/x86/x86/errata.c.diff?r1=1.20r2=1.21only_with_tag=MAINf=h
),
OpenBSD run without crash:
OpenBSD 5.3-current (GENERIC.MP) #0: Mon May 20 02:56:29 EEST 2013
root@buildbox.local:/usr/src/sys/arch/amd64/compile/GENERIC.MP
real mem = 1056956416 (1007MB)
avail mem = 1021165568 (973MB)
mainbus0 at root
bios0 at mainbus0: SMBIOS rev. 2.4 @ 0xfd970 (11 entries)
bios0: vendor Bochs version Bochs date 01/01/2007
bios0: Bochs Bochs
acpi0 at bios0: rev 0
acpi0: sleep states S3 S4 S5
acpi0: tables DSDT FACP SSDT APIC HPET SSDT
acpi0: wakeup devices
acpitimer0 at acpi0: 3579545 Hz, 24 bits
acpimadt0 at acpi0 addr 0xfee0:
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
That is quite a large hammer. It would be preferable to
find out which msr it objects to and guard it with a specific cpuid
check, and/or fix the hypervisor.
On Mon, May 20, 2013 at 10:34:43AM +0300, Roman Kravchuk wrote:
patch_amd64errata.diff
Index: amd64/amd64/amd64errata.c
===
RCS file: /cvs/src/sys/arch/amd64/amd64/amd64errata.c,v
retrieving revision 1.3
diff -u -p -u -p -r1.3 amd64errata.c
--- amd64/amd64/amd64errata.c27 Mar 2012 05:59:46 -1.3
+++ amd64/amd64/amd64errata.c19 May 2013 23:48:11 -
@@ -293,6 +293,9 @@ amd64_errata(struct cpu_info *ci)
int found = 0;
int corrected = 0;
+if (ci-ci_feature_eflags CPUIDECX_RAZ)
+return;
+
CPUID(0x8001, code, dummy, dummy, dummy);
for (i = 0; ; i += 2) {
Index: amd64/amd64/identcpu.c
===
RCS file: /cvs/src/sys/arch/amd64/amd64/identcpu.c,v
retrieving revision 1.47
diff -u -p -u -p -r1.47 identcpu.c
--- amd64/amd64/identcpu.c6 May 2013 04:32:12 -1.47
+++ amd64/amd64/identcpu.c19 May 2013 23:48:11 -
@@ -129,6 +129,7 @@ const struct {
{ CPUIDECX_AVX,AVX },
{ CPUIDECX_F16C,F16C },
{ CPUIDECX_RDRAND,RDRAND },
+{ CPUIDECX_RAZ,RAZ }
}, cpu_ecpuid_ecxfeatures[] = {
{ CPUIDECX_LAHF,LAHF },
{ CPUIDECX_CMPLEG,CMPLEG },
Index: amd64/include/specialreg.h
===
RCS file: /cvs/src/sys/arch/amd64/include/specialreg.h,v
retrieving revision 1.25
diff -u -p -u -p -r1.25 specialreg.h
--- amd64/include/specialreg.h6 May 2013 04:32:12 -1.25
+++ amd64/include/specialreg.h19 May 2013 23:48:11 -
@@ -158,6 +158,7 @@
#defineCPUIDECX_AVX0x1000/* Advanced Vector Extensions */
#defineCPUIDECX_F16C0x2000/* 16bit fp conversion */
#defineCPUIDECX_RDRAND0x4000/* RDRAND instruction */
+#defineCPUIDECX_RAZ0x8000/* RAZ. Indicates guest state. */
/*
* Structured Extended Feature Flags Parameters (CPUID function 0x7,
leaf 0)
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
On Mon, May 20, 2013 at 01:50:39PM +, Alexey E. Suslikov wrote: Jonathan Gray jsg at jsg.id.au writes: That is quite a large hammer. It would be preferable to find out which msr it objects to and guard it with a specific cpuid check, and/or fix the hypervisor. From NetBSD PR/47677 (http://gnats.netbsd.org/47677) I think x86_errata should be avoided if NetBSD running on virtual machine because accesses to MSR may be restricted While above statement is an assumption, it is highly possible for hypervisor to restrict operations on model-specific regs. For me it's kinda grounded approach, because erratas applied on host level may conflict with what guests want, increasing a possibility of screwing up things. So what is the point for guest to run erratas if hypervisor may already done that upwards? Filling the kernel full of if not really running on hardware do something else paths is asking for trouble. If a hypervisor claims to be a specific model of a processor it should not be surprised when it gets msrs that processor can handle.
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
Jonathan Gray jsg at jsg.id.au writes:
Filling the kernel full of if not really running on hardware
do something else paths is asking for trouble. If a hypervisor
claims to be a specific model of a processor it should not be
surprised when it gets msrs that processor can handle.
FreeBSD do
--- head/sys/amd64/amd64/initcpu.c 2012/03/30 16:32:41 233702
+++ head/sys/amd64/amd64/initcpu.c 2012/08/07 08:36:10 239125
@@ -91,11 +91,17 @@
*
* http://support.amd.com/us/Processor_TechDocs/41322_10h_Rev_Gd.pdf
* http://support.amd.com/us/Processor_TechDocs/44739_12h_Rev_Gd.pdf
+*
+* Hypervisors do not provide access to the errata MSR,
+* causing #GP exception on attempt to apply the errata. The
+* MSR write shall be done on host and persist globally
+* anyway, so do not try to do it when under virtualization.
*/
switch (CPUID_TO_FAMILY(cpu_id)) {
case 0x10:
case 0x12:
- wrmsr(0xc0011029, rdmsr(0xc0011029) | 1);
+ if ((cpu_feature2 CPUID2_HV) == 0)
+ wrmsr(0xc0011029, rdmsr(0xc0011029) | 1);
break;
}
}
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
On Mon, May 20, 2013 at 09:16:21AM +0300, Roman Kravchuk wrote:
I'm have problem with run OpenBSD current amd64 as guest in KVM hypervisor
on Ubuntu server with AMD CPU.
..
cpu0 at mainbus0: apid 0 (boot processor)
cpu0: AMD Phenom(tm) 9550 Quad-Core Processor, 3600.53 MHz
cpu0:
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CF
LUSH,MMX,FXSR,SSE,SSE2,SSE3,CX16,POPCNT,NXE,MMXX,FFXSR,LONG,3DNOW2,3DNOW,LAHF,CM
PLEG,SVM,AMCR8,ABM,SSE4A,MASSE,3DNOWP
cpu0: 64KB 64b/line 2-way I-cache, 64KB 64b/line 2-way D-cache, 512KB
64b/line 1
6-way L2 cache
cpu0: ITLB 255 4KB entries direct-mapped, 255 4MB entries direct-mapped
cpu0: DTLB 255 4KB entries direct-mapped, 255 4MB entries direct-mapped
kernel: protection fault trap, code=0
Stopped at aesni_setup+0x1a0: rdmsr
aesni_setup() at aesni setup+0x1a0
amd64_errata() at amd64 errata+0xc9
identifycpu() at identifycpu+0x729
cpu attach() at cpu_attach+0x2ce
config_attach() at config_attach+0x1d4
mpbios_cpu() at mpbios_cpu+0x5b
mpbios_scan() at mpbios_scan+0x355
config_attach() at config_attach+0x1d4
bios_attach() at bios_attach+0x296
config_attach() at config_attach+0x1d4
end trace frame: 0x81de9e30, count: 0
ddb{0}
This is another KVM bug. It's pretending to be an AMD CPU, but not
emulating one that actually exists.
-Bryan.
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
Mike Larkin mlarkin at azathoth.net writes: You're kidding, right? Could you guys tell what exactly wrong with FreeBSD/NetBSD approach?
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
You're kidding, right? Could you guys tell what exactly wrong with FreeBSD/NetBSD approach? So basically, we're told that these VM's are emulating real machines. Except when we try to manage the hardware -- in the specific way that the specific hardware must be handled -- the VM fails to behave like the real machine which it says it is. Do you simply lack comprehension of where we'll end up a decade of following that road? If these VM's are real VM's the should start emulating the machines they claim to be emulating correctly, or they should start advertising that they are something different, so that we can isolate the bullshit factor.
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
On Mon, May 20, 2013 at 6:15 PM, Alexey E. Suslikov alexey.susli...@gmail.com wrote: Mike Larkin mlarkin at azathoth.net writes: You're kidding, right? Could you guys tell what exactly wrong with FreeBSD/NetBSD approach? Adding some silly workarounds to the kernel for a bug that is a *KVM bug*.
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
Theo de Raadt deraadt at cvs.openbsd.org writes:
If these VM's are real VM's the should start emulating the machines
they claim to be emulating correctly, or they should start advertising
that they are something different, so that we can isolate the bullshit
factor.
Ok. I see.
Could we trim that down to the following?
--- sys/arch/amd64/amd64/identcpu.c.origMon May 20 19:58:06 2013
+++ sys/arch/amd64/amd64/identcpu.c Mon May 20 20:01:08 2013
@@ -127,6 +127,7 @@
{ CPUIDECX_AVX, AVX },
{ CPUIDECX_F16C,F16C },
{ CPUIDECX_RDRAND, RDRAND },
+ { CPUIDECX_HV, HV },
}, cpu_ecpuid_ecxfeatures[] = {
{ CPUIDECX_LAHF,LAHF },
{ CPUIDECX_CMPLEG, CMPLEG },
--- sys/arch/amd64/include/specialreg.h.origMon May 20 20:01:56 2013
+++ sys/arch/amd64/include/specialreg.h Mon May 20 20:06:09 2013
@@ -158,6 +158,7 @@
#defineCPUIDECX_AVX0x1000 /* Advanced Vector Extensions */
#defineCPUIDECX_F16C 0x2000 /* 16bit fp conversion */
#defineCPUIDECX_RDRAND 0x4000 /* RDRAND instruction */
+#defineCPUIDECX_HV 0x8000 /* Hypervisor presence
*/
/*
* Structured Extended Feature Flags Parameters (CPUID function 0x7, leaf 0)
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
On Mon, May 20, 2013 at 8:42 PM, Mike Larkin mlar...@azathoth.net wrote:
On Mon, May 20, 2013 at 05:11:35PM +, Alexey E. Suslikov wrote:
Theo de Raadt deraadt at cvs.openbsd.org writes:
If these VM's are real VM's the should start emulating the machines
they claim to be emulating correctly, or they should start advertising
that they are something different, so that we can isolate the bullshit
factor.
Ok. I see.
Could we trim that down to the following?
--- sys/arch/amd64/amd64/identcpu.c.orig Mon May 20 19:58:06 2013
+++ sys/arch/amd64/amd64/identcpu.c Mon May 20 20:01:08 2013
@@ -127,6 +127,7 @@
{ CPUIDECX_AVX, AVX },
{ CPUIDECX_F16C,F16C },
{ CPUIDECX_RDRAND, RDRAND },
+ { CPUIDECX_HV, HV },
}, cpu_ecpuid_ecxfeatures[] = {
{ CPUIDECX_LAHF,LAHF },
{ CPUIDECX_CMPLEG, CMPLEG },
--- sys/arch/amd64/include/specialreg.h.orig Mon May 20 20:01:56 2013
+++ sys/arch/amd64/include/specialreg.h Mon May 20 20:06:09 2013
@@ -158,6 +158,7 @@
#define CPUIDECX_AVX0x1000 /* Advanced Vector Extensions
*/
#define CPUIDECX_F16C 0x2000 /* 16bit fp conversion */
#define CPUIDECX_RDRAND 0x4000 /* RDRAND instruction */
+#define CPUIDECX_HV 0x8000 /* Hypervisor presence
*/
/*
* Structured Extended Feature Flags Parameters (CPUID function 0x7, leaf
0)
That's certainly less objectionable but I'm not sure what useful information
this diff provides.
Seen in dmesg, HV flag will indicate operating system is run under hypervisor
and weird things are possible while running kernel code which depends on CPU
features.
After all, it is kinda documented by AMD on page 570 of
http://support.amd.com/us/Processor_TechDocs/24594_APM_v3.pdf
(AMD named it RAZ, but I put meaningful name like in FreeBSD - should we
put a reference to above mentioned document near the define?).
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
On Mon, May 20, 2013 at 8:42 PM, Mike Larkin mlar...@azathoth.net wrote:
On Mon, May 20, 2013 at 05:11:35PM +, Alexey E. Suslikov wrote:
Theo de Raadt deraadt at cvs.openbsd.org writes:
If these VM's are real VM's the should start emulating the machines
they claim to be emulating correctly, or they should start advertising
that they are something different, so that we can isolate the bullshit
factor.
Ok. I see.
Could we trim that down to the following?
--- sys/arch/amd64/amd64/identcpu.c.orig Mon May 20 19:58:06 2013
+++ sys/arch/amd64/amd64/identcpu.c Mon May 20 20:01:08 2013
@@ -127,6 +127,7 @@
{ CPUIDECX_AVX, AVX },
{ CPUIDECX_F16C,F16C },
{ CPUIDECX_RDRAND, RDRAND },
+ { CPUIDECX_HV, HV },
}, cpu_ecpuid_ecxfeatures[] = {
{ CPUIDECX_LAHF,LAHF },
{ CPUIDECX_CMPLEG, CMPLEG },
--- sys/arch/amd64/include/specialreg.h.orig Mon May 20 20:01:56 2013
+++ sys/arch/amd64/include/specialreg.h Mon May 20 20:06:09 2013
@@ -158,6 +158,7 @@
#define CPUIDECX_AVX0x1000 /* Advanced Vector
Extensions */
#define CPUIDECX_F16C 0x2000 /* 16bit fp conversion */
#define CPUIDECX_RDRAND 0x4000 /* RDRAND instruction */
+#define CPUIDECX_HV 0x8000 /* Hypervisor
presence */
/*
* Structured Extended Feature Flags Parameters (CPUID function 0x7,
leaf 0)
That's certainly less objectionable but I'm not sure what useful information
this diff provides.
Seen in dmesg, HV flag will indicate operating system is run under hypervisor
and weird things are possible while running kernel code which depends on CPU
features.
After all, it is kinda documented by AMD on page 570 of
http://support.amd.com/us/Processor_TechDocs/24594_APM_v3.pdf
(AMD named it RAZ, but I put meaningful name like in FreeBSD - should we
put a reference to above mentioned document near the define?).
Your statements here are trying to convince us of something which is
false.
AMD says RAZ. Reserved for use by hypervisor to indicate guest status.
That sentence does not translate to The hypervisor is heavily broken
and fails to completely emulate the machine otherwise advertised by
the rest of the CPUID fields.
It does not indicate that weird things are possible. If those weird
things are possible, it is not because the hardware is broken, but
because the *emulation of the hardware* by the VM is broken!
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
On Mon, May 20, 2013 at 8:59 PM, Theo de Raadt dera...@cvs.openbsd.org
wrote:
On Mon, May 20, 2013 at 8:42 PM, Mike Larkin mlar...@azathoth.net wrote:
On Mon, May 20, 2013 at 05:11:35PM +, Alexey E. Suslikov wrote:
Theo de Raadt deraadt at cvs.openbsd.org writes:
If these VM's are real VM's the should start emulating the machines
they claim to be emulating correctly, or they should start advertising
that they are something different, so that we can isolate the
bullshit
factor.
Ok. I see.
Could we trim that down to the following?
--- sys/arch/amd64/amd64/identcpu.c.orig Mon May 20 19:58:06 2013
+++ sys/arch/amd64/amd64/identcpu.c Mon May 20 20:01:08 2013
@@ -127,6 +127,7 @@
{ CPUIDECX_AVX, AVX },
{ CPUIDECX_F16C,F16C },
{ CPUIDECX_RDRAND, RDRAND },
+ { CPUIDECX_HV, HV },
}, cpu_ecpuid_ecxfeatures[] = {
{ CPUIDECX_LAHF,LAHF },
{ CPUIDECX_CMPLEG, CMPLEG },
--- sys/arch/amd64/include/specialreg.h.orig Mon May 20 20:01:56 2013
+++ sys/arch/amd64/include/specialreg.h Mon May 20 20:06:09 2013
@@ -158,6 +158,7 @@
#define CPUIDECX_AVX0x1000 /* Advanced Vector
Extensions */
#define CPUIDECX_F16C 0x2000 /* 16bit fp conversion */
#define CPUIDECX_RDRAND 0x4000 /* RDRAND instruction */
+#define CPUIDECX_HV 0x8000 /* Hypervisor
presence */
/*
* Structured Extended Feature Flags Parameters (CPUID function 0x7,
leaf 0)
That's certainly less objectionable but I'm not sure what useful
information
this diff provides.
Seen in dmesg, HV flag will indicate operating system is run under
hypervisor
and weird things are possible while running kernel code which depends on
CPU
features.
After all, it is kinda documented by AMD on page 570 of
http://support.amd.com/us/Processor_TechDocs/24594_APM_v3.pdf
(AMD named it RAZ, but I put meaningful name like in FreeBSD - should we
put a reference to above mentioned document near the define?).
Your statements here are trying to convince us of something which is
false.
AMD says RAZ. Reserved for use by hypervisor to indicate guest status.
That sentence does not translate to The hypervisor is heavily broken
and fails to completely emulate the machine otherwise advertised by
the rest of the CPUID fields.
It does not indicate that weird things are possible. If those weird
things are possible, it is not because the hardware is broken, but
because the *emulation of the hardware* by the VM is broken!
You misunderstood my point.
I'm not trying to convince, but avoid useless work/talk in the future:
Yes you are. You have an agenda.
You want to make us work around a bug, rather than talk to the
originators of the problem.
Re: Kernel panic on current amd64 running under Ubuntu KVM (patch included)
On Tue, May 21, 2013 at 00:32, Alexey Suslikov wrote: Sometimes we warn users, sometimes not (but we aware of the problem). What is the criteria? Is it a device we claim to support? (Or are interested in supporting?)
