(Emailing from this email address as to help you not publish my actual
email address by mistake. I'm reachable on this email address the
next months as it looks.)
Hi,
On a QEMU/KVM 1.1.2-r2 machine with libvirt CPU setting <cpu
mode='host-model'><model fallback='allow'/></cpu> running on a host
"cpu0: Intel Core i7 9xx (Nehalem Class Core i7), 2800.70 Mhz", I get the
following startup behavior from OpenBSD 5.2 from the
newly installed system booted the first time (funnily enough the
installation CD's kernel boots fine, perhaps it runs in a
compat mode though because I don't find neither the nvram nor the mtrr row
there, on first glance, anyhow):
nvram: invalid checksum
mtrr: Pentium Pro MTRR support
kernel: protection fault trap, code=0
Stopped at intelcore_update_sensor+0x17: rdmsr
ddb>
This bug is caused in
http://fxr.watson.org/fxr/source/arch/amd64/amd64/identcpu.c?v=OPENBSD row
132.
It was introduced 2007 here
http://marc.info/?l=openbsd-tech&m=118063274617707 .
The patch at the bottom of this file provides a fix, though who knows maybe
it disables more things than necessary.
Please note that this bug kind of could be anticipated, given the comments
at the bugging procedure:
115 /*
116 * Temperature read on the CPU is relative to the maximum
117 * temperature supported by the CPU, Tj(Max).
118 * Poorly documented, refer to:
119 * http://softwarecommunity.intel.com/isn/Community/
120 * en-US/forums/thread/30228638.aspx
..
124 */
By this I conclude this bug reported to you. From reading Intel's specs of
the RDMSR instruction, I do not get to clarity
about whether this should be considered an OpenBSD bug (i.e. the fact that
OpenBSD uses the instruction), or a QEMU/KVM bug
(i.e. the fact that KVM causes segmentation fault on its invocation).
For a side note, there seems to be some Linux systems that run into this
instruction and they report it in the syslog
and do not crash.
Thank you!
Mikael
Refs:
http://libvirt.org/formatdomain.html#elementsCPU
http://code.metager.de/source/xref/libvirt/src/cpu/cpu_map.xml
--
Patch:
These are rows 125-147 of /source/arch/amd64/amd64/identcpu.c :
void
intelcore_update_sensor(void *args)
{
struct cpu_info *ci = (struct cpu_info *) args;
u_int64_t msr;
int max = 100;
if (rdmsr(MSR_TEMPERATURE_TARGET) & MSR_TEMPERATURE_TARGET_LOW_BIT)
max = 85;
msr = rdmsr(MSR_THERM_STATUS);
if (msr & MSR_THERM_STATUS_VALID_BIT) {
ci->ci_sensor.value = max - MSR_THERM_STATUS_TEMP(msr);
/* micro degrees */
ci->ci_sensor.value *= 1000000;
/* kelvin */
ci->ci_sensor.value += 273150000;
ci->ci_sensor.flags &= ~SENSOR_FINVALID;
} else {
ci->ci_sensor.value = 0;
ci->ci_sensor.flags |= SENSOR_FINVALID;
}
}
Change them to:
void
intelcore_update_sensor(void *args)
{
struct cpu_info *ci = (struct cpu_info *) args;
// u_int64_t msr; - as not to produce unused variable = error
// int max = 100; - "
// if (rdmsr(MSR_TEMPERATURE_TARGET) &
MSR_TEMPERATURE_TARGET_LOW_BIT)
// max = 85;
// msr = rdmsr(MSR_THERM_STATUS);
// if (msr & MSR_THERM_STATUS_VALID_BIT) {
// ci->ci_sensor.value = max - MSR_THERM_STATUS_TEMP(msr);
// /* micro degrees */
// ci->ci_sensor.value *= 1000000;
// /* kelvin */
// ci->ci_sensor.value += 273150000;
// ci->ci_sensor.flags &= ~SENSOR_FINVALID;
// } else {
ci->ci_sensor.value = 0;
ci->ci_sensor.flags |= SENSOR_FINVALID;
// }
}
When running with workaround-patched kernel:
$ cat /var/run/dmesg.boot
OpenBSD 5.2-current (GENERIC.MP) #2: Thu Nov 15 13:05:13 CET 2012
[email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP
real mem = 1072680960 (1022MB)
avail mem = 1021698048 (974MB)
mainbus0 at root
bios0 at mainbus0: SMBIOS rev. 2.4 @ 0x3ffff980 (41 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 0xfee00000: PC-AT compat
acpihpet0 at acpi0: 100000000 Hz
acpiprt0 at acpi0: bus 0 (PCI0)
mpbios0 at bios0: Intel MP Specification 1.4
cpu0 at mainbus0: apid 0 (boot processor)
cpu0: Intel Core i7 9xx (Nehalem Class Core i7), 2963.42 MHz
cpu0:
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,MMX,FXSR,SSE,SSE2,SS,SSE3,SSSE3,CX16,SSE4.1,SSE4.2,POPCNT,NXE,LONG,LAHF,PERF
cpu0: 64KB 64b/line 2-way I-cache, 64KB 64b/line 2-way D-cache, 512KB
64b/line 16-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
cpu0: apic clock running at 1479MHz
cpu1 at mainbus0: apid 1 (application processor)
cpu1: Intel Core i7 9xx (Nehalem Class Core i7), 4566.49 MHz
cpu1:
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,MMX,FXSR,SSE,SSE2,SS,SSE3,SSSE3,CX16,SSE4.1,SSE4.2,POPCNT,NXE,LONG,LAHF,PERF
cpu1: 64KB 64b/line 2-way I-cache, 64KB 64b/line 2-way D-cache, 512KB
64b/line 16-way L2 cache
cpu1: ITLB 255 4KB entries direct-mapped, 255 4MB entries direct-mapped
cpu1: DTLB 255 4KB entries direct-mapped, 255 4MB entries direct-mapped
mpbios0: bus 0 is type PCI
mpbios0: bus 1 is type ISA
ioapic0 at mainbus0: apid 2 pa 0xfec00000, version 11, 24 pins
ioapic0: misconfigured as apic 0, remapped to apid 2
pci0 at mainbus0 bus 0
pchb0 at pci0 dev 0 function 0 "Intel 82441FX" rev 0x02
pcib0 at pci0 dev 1 function 0 "Intel 82371SB ISA" rev 0x00
pciide0 at pci0 dev 1 function 1 "Intel 82371SB IDE" rev 0x00: DMA, channel
0 wired to compatibility, channel 1 wired to compatibility
wd0 at pciide0 channel 0 drive 0: <QEMU HARDDISK>
wd0: 16-sector PIO, LBA48, 51200MB, 104857600 sectors
atapiscsi0 at pciide0 channel 0 drive 1
scsibus0 at atapiscsi0: 2 targets
cd0 at scsibus0 targ 0 lun 0: <QEMU, QEMU DVD-ROM, 1.1.> ATAPI 5/cdrom
removable
wd0(pciide0:0:0): using PIO mode 4, DMA mode 2
cd0(pciide0:0:1): using PIO mode 4, DMA mode 2
pciide0: channel 1 disabled (no drives)
uhci0 at pci0 dev 1 function 2 "Intel 82371SB USB" rev 0x01: apic 2 int 11
piixpm0 at pci0 dev 1 function 3 "Intel 82371AB Power" rev 0x03: apic 2 int
9
iic0 at piixpm0
iic0: addr 0x4c 48=00 words 00=0000 01=0000 02=0000 03=0000 04=0000 05=0000
06=0000 07=0000
iic0: addr 0x4e 48=00 words 00=0000 01=0000 02=0000 03=0000 04=0000 05=0000
06=0000 07=0000
vga1 at pci0 dev 2 function 0 "Cirrus Logic CL-GD5446" rev 0x00
wsdisplay0 at vga1 mux 1: console (80x25, vt100 emulation)
wsdisplay0: screen 1-5 added (80x25, vt100 emulation)
re0 at pci0 dev 3 function 0 "Realtek 8139" rev 0x20: RTL8139C+ (0x7480),
apic 2 int 11, address 1c:0f:7e:70:0d:5e
rlphy0 at re0 phy 0: RTL internal PHY
virtio0 at pci0 dev 4 function 0 "Qumranet Virtio Memory" rev 0x00: Virtio
Memory Balloon Device
virtio0: no matching child driver; not configured
isa0 at pcib0
isadma0 at isa0
pckbc0 at isa0 port 0x60/5
pckbd0 at pckbc0 (kbd slot)
pckbc0: using irq 1 for kbd slot
wskbd0 at pckbd0: console keyboard, using wsdisplay0
pms0 at pckbc0 (aux slot)
pckbc0: using irq 12 for aux slot
wsmouse0 at pms0 mux 0
pcppi0 at isa0 port 0x61
spkr0 at pcppi0
fdc0 at isa0 port 0x3f0/6 irq 6 drq 2
fd0 at fdc0 drive 0: density unknown
fd1 at fdc0 drive 1: density unknown
usb0 at uhci0: USB revision 1.0
uhub0 at usb0 "Intel UHCI root hub" rev 1.00/1.00 addr 1
nvram: invalid checksum
mtrr: Pentium Pro MTRR support
vscsi0 at root
scsibus1 at vscsi0: 256 targets
softraid0 at root
scsibus2 at softraid0: 256 targets
root on wd0a (1b840e0498b5beb4.a) swap on wd0b dump on wd0b
clock: unknown CMOS layout
softraid0: incorrect key or passphrase
sd0 at scsibus2 targ 1 lun 0: <OPENBSD, SR CRYPTO, 005> SCSI2 0/direct fixed
sd0: 49920MB, 512 bytes/sector, 102237132 sectors
