Re: Buggy IOMMU support in Coreboot on Chromebook Pixel 2 i7-5600U

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 14/08/15 08:13, fowlslegs@riseup.net wrote:
> On the VT-d troubleshooting page, I was informed to shoot you all a 
> message if Xen had to deactivate my VT-d due to errors in my BIOS (in 
> this case Coreboot). I am running John Lewis' Coreboot ROM for the 
> Chromebook Pixel 2 (samus) w/ the i7-5600U processor and Xen 4.4.2 on 
> Qubes. I downloaded and cracked open (for lack of better words) John 
> Lewis's Coreboot image (which is a modified version of the one in the 
> Google repos) and found that src/arch/x86/acpi.c had the same section 
> added by the http://review.coreboot.org/#/c/1654/ commit written by 
> Patrick Georgi a few years back that is supposed to provide ACPI DMAR 
> tables. The problem might just be the code is out of date for modern 
> processors or maybe it has just not been tested against many CPUs.
>
> It does appear that there has been changes to this acpi.c file in the 
> Coreboot master branch, which makes me wonder if building against that 
> would fix my problems. Realistically though, I have barely any 
> experience or knowledge with Coreboot hacking and I'm assuming there 
> is a web of dependencies that I couldn't figure out without possibly 
> months of research, trial, and error.
>
> Anyway, just wanted to send in this report as maybe you don't get too 
> many involving Coreboot and maybe you might find it interesting or in 
> the minute chance you might be able to help me out. Anyway, here's the 
> output of `xl dmesg`:

Please reboot and use "iommu=verbose,debug" on the Xen command line, 
which will offer more information.

~Andrew

>
>
> Xen 4.4.2-6.fc20
> (XEN) Xen version 4.4.2 (user@) (gcc (GCC) 4.8.3 20140911 (Red Hat 
> 4.8.3-7)) debug=n Thu Jul 23 20:12:15 UTC 2015
> (XEN) Latest ChangeSet:
> (XEN) Bootloader: GRUB 2.00
> (XEN) Command line: placeholder console=none dom0_mem=min:1024M
> (XEN) Video information:
> (XEN)  VGA is text mode 80x25, font 8x16
> (XEN) Disc information:
> (XEN)  Found 2 MBR signatures
> (XEN)  Found 2 EDD information structures
> (XEN) Xen-e820 RAM map:
> (XEN)  0000000000000000 - 000000000009fc00 (usable)
> (XEN)  000000000009fc00 - 00000000000a0000 (reserved)
> (XEN)  00000000000f0000 - 0000000000100000 (reserved)
> (XEN)  0000000000100000 - 000000007ce27000 (usable)
> (XEN)  000000007ce27000 - 0000000080000000 (reserved)
> (XEN)  00000000f0000000 - 00000000f4000000 (reserved)
> (XEN)  00000000fed10000 - 00000000fed1a000 (reserved)
> (XEN)  00000000fed40000 - 00000000fed45000 (reserved)
> (XEN)  00000000fed80000 - 00000000fed85000 (reserved)
> (XEN)  0000000100000000 - 000000047f000000 (usable)
> (XEN) ACPI: RSDP 000F2760, 0024 (r2 CORE  )
> (XEN) ACPI: XSDT 7CF440E0, 004C (r1 CORE   COREBOOT        0 
> CORE        0)
> (XEN) ACPI: FACP 7CF48970, 00F4 (r5 CORE   COREBOOT        0 
> CORE        1)
> (XEN) ACPI: DSDT 7CF44250, 4720 (r2 COREv4 COREBOOT 20110725 INTL 
> 20130117)
> (XEN) ACPI: FACS 7CF44210, 0040
> (XEN) ACPI: HPET 7CF48A70, 0038 (r1 CORE   COREBOOT        0 
> CORE        0)
> (XEN) ACPI: APIC 7CF48AB0, 006C (r1 CORE   COREBOOT        0 
> CORE        0)
> (XEN) ACPI: MCFG 7CF48B20, 003C (r1 CORE   COREBOOT        0 
> CORE        0)
> (XEN) ACPI: SSDT 7CF49BC0, 0FF8 (r2 CORE   COREBOOT       2A 
> CORE       2A)
> (XEN) System RAM: 16317MB (16709400kB)
> (XEN) Domain heap initialised
> (XEN) Processor #0 7:13 APIC version 21
> (XEN) Processor #1 7:13 APIC version 21
> (XEN) Processor #3 7:13 APIC version 21
> (XEN) Processor #2 7:13 APIC version 21
> (XEN) IOAPIC[0]: apic_id 2, version 32, address 0xfec00000, GSI 0-39
> (XEN) Enabling APIC mode:  Flat.  Using 1 I/O APICs
> (XEN) Not enabling x2APIC: depends on iommu_supports_eim.
> (XEN) Using scheduler: SMP Credit Scheduler (credit)
> (XEN) Detected 2394.544 MHz processor.
> (XEN) Initing memory sharing.
> (XEN) xstate_init: using cntxt_size: 0x340 and states: 0x7
> (XEN) I/O virtualisation disabled
> (XEN) Enabled directed EOI with ioapic_ack_old on!
> (XEN) ENABLING IO-APIC IRQs
> (XEN)  -> Using old ACK method
> (XEN) Platform timer is 14.318MHz HPET
> (XEN) Allocated console ring of 16 KiB.
> (XEN) VMX: Supported advanced features:
> (XEN)  - APIC MMIO access virtualisation
> (XEN)  - APIC TPR shadow
> (XEN)  - Extended Page Tables (EPT)
> (XEN)  - Virtual-Processor Identifiers (VPID)
> (XEN)  - Virtual NMI
> (XEN)  - MSR direct-access bitmap
> (XEN)  - Unrestricted Guest
> (XEN) HVM: ASIDs enabled.
> (XEN) HVM: VMX enabled
> (XEN) HVM: Hardware Assisted Paging (HAP) detected
> (XEN) HVM: HAP page sizes: 4kB, 2MB, 1GB
> (XEN) Brought up 4 CPUs
> (XEN) *** LOADING DOMAIN 0 ***
> (XEN)  Xen  kernel: 64-bit, lsb, compat32
> (XEN)  Dom0 kernel: 64-bit, PAE, lsb, paddr 0x1000000 -> 0x204d000
> (XEN) PHYSICAL MEMORY ARRANGEMENT:
> (XEN)  Dom0 alloc.:   0000000468000000->0000000470000000 (4056562 
> pages to be allocated)
> (XEN)  Init. ramdisk: 000000047cb6a000->000000047f000000
> (XEN) VIRTUAL MEMORY ARRANGEMENT:
> (XEN)  Loaded kernel: ffffffff81000000->ffffffff8204d000
> (XEN)  Init. ramdisk: 0000000000000000->0000000000000000
> (XEN)  Phys-Mach map: ffffffff8204d000->ffffffff83f92440
> (XEN)  Start info:    ffffffff83f93000->ffffffff83f934b4
> (XEN)  Page tables:   ffffffff83f94000->ffffffff83fb9000
> (XEN)  Boot stack:    ffffffff83fb9000->ffffffff83fba000
> (XEN)  TOTAL:         ffffffff80000000->ffffffff84400000
> (XEN)  ENTRY ADDRESS: ffffffff81d3f1f0
> (XEN) Dom0 has maximum 4 VCPUs
> (XEN) Scrubbing Free RAM: .done.
> (XEN) Initial low memory virq threshold set at 0x4000 pages.
> (XEN) Std. Loglevel: Errors and warnings
> (XEN) Guest Loglevel: Nothing (Rate-limited: Errors and warnings)
> (XEN) *** Serial input -> DOM0 (type 'CTRL-a' three times to switch 
> input to Xen)
> (XEN) Freed 272kB init memory.
> (XEN) traps.c:2524:d0 Domain attempted WRMSR 00000000c0000081 from 
> 0xe023e00800000000 to 0x0023001000000000.
> (XEN) traps.c:2524:d0 Domain attempted WRMSR 00000000c0000082 from 
> 0xffff82d0802b3000 to 0xffffffff817634d0.
> (XEN) traps.c:2524:d0 Domain attempted WRMSR 00000000c0000083 from 
> 0xffff82d0802b3080 to 0xffffffff817658e0.
> (XEN) traps.c:2524:d0 Domain attempted WRMSR 0000000000000174 from 
> 0x000000000000e008 to 0x0000000000000010.
> (XEN) traps.c:2524:d0 Domain attempted WRMSR 0000000000000175 from 
> 0xffff82d0802b7fc0 to 0x0000000000000000.
> (XEN) traps.c:2524:d0 Domain attempted WRMSR 0000000000000176 from 
> 0xffff82d08021aff0 to 0xffffffff81765bf0.
> (XEN) traps.c:2524:d0 Domain attempted WRMSR 00000000c0000083 from 
> 0xffff82d0802b3080 to 0xffffffff81765e30.
> (XEN) traps.c:2524:d0 Domain attempted WRMSR 00000000c0000084 from 
> 0x0000000000034700 to 0x0000000000047700.
> (XEN) traps.c:2524:d0 Domain attempted WRMSR 00000000c0000081 from 
> 0xe023e00800000000 to 0x0023001000000000.
> (XEN) traps.c:2524:d0 Domain attempted WRMSR 00000000c0000082 from 
> 0xffff830473323000 to 0xffffffff817634d0.
>
>
> ~*~*~*~*~*~*
> Noah
>
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