There is no cpuid feature method of detecting MSR_TEMPERATURE_TARGET presence. So whatever is faking/masking the hardware should either not advertise the thermal sensor cpuid bit or implement MSR_TEMPERATURE_TARGET. The other alternative is catching the fault caused by doing an unsupported msr.
You should pick a different fake cpu if it can't provide what a real core family processor implements. Disabling the cpu sensor everywhere as you propose is obviously not a solution. On Thu, Nov 15, 2012 at 03:29:41PM +0200, Mikael wrote: > (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
