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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: arm (qemu -M virt) 64 bit xen running 32 bit guest problem
> > > Looking at the code, this seems like an issue when trying to
> > > translate a guest virtual address to a machine address.
> > >
> > > A few questions:
> > > - Which QEMU version are you using?
> > > - What's your Linux configuration? Are you using LPAE or short page
> tables?
> >
> > I am using default ubuntu package on bionic:
> >
> > $ qemu-system-aarch64 --version
> > QEMU emulator version 2.11.1(Debian 1:2.11+dfsg-1ubuntu7.29) Copyright
> > (c) 2003-2017 Fabrice Bellard and the QEMU Project developers
> >
> > I just tried the stable-4.14 branch and this "Invalid MFN 0x..." doesn't
> happen. It was on the master branch where I encountered this problem.
> > However, I don't seem to get anything to call guest_printk() after making
> hypervisor_console_io call even for 64-bit guest in this version (worked on
> master). This is a separate question: could that be a XEN compile option
> problem as I see "debug=n" from xen register dump:
> > (XEN) ----[ Xen-4.14.1-pre arm64 debug=n Not tainted ]----
>
> The call chain is:
>
> xen/drivers/char/console.c:do_console_io
> xen/drivers/char/console.c:guest_console_write
> xen/drivers/char/console.c:guest_printk
>
> You can enable debug through kconfig by doing "make menuconfig" under
> xen/
Thank you for pointing this out! After I enabled the verbose debug messages,
the hvc #0xea1 call is now taking effect. I'm seeing the previous problem of
"invalid MFN" after that. It seems that the pointer 0x40000058 had been mapped
to MFN 0x2be08. How do I debug or where locate the problem? I'm very new to XEN
so it's no obvious yet to me from reading the source code how after
guest_printk(), xen translate the addresses.
This is the output of my guest boot up:
/ # xl -v create -c /share/misc/bm.cfg
Parsing config from /share/misc/bm.cfg
libxl: info: libxl_create.c:122:libxl__domain_build_info_setdefault: qemu-xen
is unavailable, using qemu-xen-traditional instead: No such file or directory
libxl: detail: libxl_create.c:623:libxl__domain_make: passthrough: disabled
domainbuilder: detail: xc_dom_allocate: cmdline="", features=""
domainbuilder: detail: xc_dom_kernel_file: filename="/share/misc/bm.img"
domainbuilder: detail: xc_dom_boot_xen_init: ver 4.14, caps xen-3.0-aarch64
xen-3.0-armv7l
domainbuilder: detail: xc_dom_rambase_init: RAM starts at 40000
domainbuilder: detail: xc_dom_parse_image: called
domainbuilder: detail: xc_dom_find_loader: trying multiboot-binary loader ...
domainbuilder: detail: loader probe failed
domainbuilder: detail: xc_dom_find_loader: trying Linux zImage (ARM64) loader
...
domainbuilder: detail: xc_dom_probe_zimage64_kernel: kernel is not an arm64
Image
domainbuilder: detail: loader probe failed
domainbuilder: detail: xc_dom_find_loader: trying Linux zImage (ARM32) loader
...
domainbuilder: detail: loader probe OK
domainbuilder: detail: xc_dom_parse_zimage32_kernel: called
domainbuilder: detail: xc_dom_parse_zimage32_kernel: xen-3.0-armv7l: 0x40008000
-> 0x4000807c
domainbuilder: detail: xc_dom_devicetree_mem: called
domainbuilder: detail: xc_dom_mem_init: mem 128 MB, pages 0x8000 pages, 4k each
domainbuilder: detail: xc_dom_mem_init: 0x8000 pages
domainbuilder: detail: xc_dom_boot_mem_init: called
domainbuilder: detail: set_mode: guest xen-3.0-armv7l, address size 32
domainbuilder: detail: populate_guest_memory: populating RAM @
0000000040000000-0000000048000000 (128MB)
domainbuilder: detail: populate_one_size: populated 0x40/0x40 entries with
shift 9
domainbuilder: detail: meminit: placing boot modules at 0x47fff000
domainbuilder: detail: meminit: devicetree: 0x47fff000 -> 0x48000000
domainbuilder: detail: xc_dom_build_image: called
domainbuilder: detail: xc_dom_pfn_to_ptr_retcount: domU mapping: pfn
0x40008+0x1 at 0xffff8c229000
domainbuilder: detail: xc_dom_alloc_segment: kernel : 0x40008000 ->
0x40009000 (pfn 0x40008 + 0x1 pages)
domainbuilder: detail: xc_dom_load_zimage_kernel: called
domainbuilder: detail: xc_dom_load_zimage_kernel: kernel seg
0x40008000-0x40009000
domainbuilder: detail: xc_dom_load_zimage_kernel: copy 124 bytes from blob
0xffff8c6c0000 to dst 0xffff8c229000
domainbuilder: detail: xc_dom_pfn_to_ptr_retcount: domU mapping: pfn
0x47fff+0x1 at 0xffff8c228000
domainbuilder: detail: xc_dom_alloc_segment: devicetree : 0x47fff000 ->
0x48000000 (pfn 0x47fff + 0x1 pages)
domainbuilder: detail: alloc_magic_pages: called
domainbuilder: detail: xc_dom_build_image : virt_alloc_end : 0x48000000
domainbuilder: detail: xc_dom_build_image : virt_pgtab_end : 0x0
domainbuilder: detail: xc_dom_boot_image: called
domainbuilder: detail: bootearly: doing nothing
domainbuilder: detail: xc_dom_compat_check: supported guest type:
xen-3.0-aarch64
domainbuilder: detail: xc_dom_compat_check: supported guest type:
xen-3.0-armv7l <= matches
domainbuilder: detail: start_info_arm: called
domainbuilder: detail: domain builder memory footprint
domainbuilder: detail: allocated
domainbuilder: detail: malloc : 2848 bytes
domainbuilder: detail: anon mmap : 0 bytes
domainbuilder: detail: mapped
domainbuilder: detail: file mmap : 124 bytes
domainbuilder: detail: domU mmap : 8192 bytes
domainbuilder: detail: vcpu_arm32: called
domainbuilder: detail: Initial state CPSR 0x1d3 PC 0x40008000
domainbuilder: detail: compat_gnttab_hvm_seed: d5: pfn=0x38000
domainbuilder: detail: xc_dom_set_gnttab_entry: d5 gnt[0] -> d0 0x39000
domainbuilder: detail: xc_dom_set_gnttab_entry: d5 gnt[1] -> d0 0x39001
domainbuilder: detail: xc_dom_release: called
(XEN) p2m.c:1919: d5v0: Invalid MFN 0x2be08
The 32-bit guest is very simple, it calls hvc very early in and uses physical
address:
$ arm-none-eabi-objdump -d bm.elf
bm.elf: file format elf32-littlearm
Disassembly of section .text:
40008000 <_stext>:
40008000: 13100a4d tstne r0, #315392 ; 0x4d000
40008004: 13100a4d tstne r0, #315392 ; 0x4d000
40008008: 13100a4d tstne r0, #315392 ; 0x4d000
4000800c: 13100a4d tstne r0, #315392 ; 0x4d000
40008010: 13100a4d tstne r0, #315392 ; 0x4d000
40008014: 13100a4d tstne r0, #315392 ; 0x4d000
40008018: 13100a4d tstne r0, #315392 ; 0x4d000
4000801c: e320f000 nop {0}
40008020: ea000006 b 40008040 <reset>
40008024: 016f2818 .word 0x016f2818
40008028: 00000000 .word 0x00000000
4000802c: 0079c200 .word 0x0079c200
40008030: 04030201 .word 0x04030201
40008034: e320f000 nop {0}
40008038: e320f000 nop {0}
4000803c: e320f000 nop {0}
40008040 <reset>:
40008040: e3a00000 mov r0, #0
40008044: e3a01023 mov r1, #35 ; 0x23
40008048: e28f2008 add r2, pc, #8
4000804c: e3a0c012 mov ip, #18
40008050: e140ea71 hvc 3745 ; 0xea1
40008054: eafffffe b 40008054 <reset+0x14>
40008058 <banner>:
40008058: 65726854 .word 0x65726854
4000805c: 2f586461 .word 0x2f586461
40008060: 204e4558 .word 0x204e4558
40008064: 746e6f43 .word 0x746e6f43
40008068: 656e6961 .word 0x656e6961
4000806c: 6f422072 .word 0x6f422072
40008070: 6e69746f .word 0x6e69746f
40008074: 70752067 .word 0x70752067
40008078: 000a0d21 .word 0x000a0d21
Thank you!
>
> > I'm ignoring 32-bit Linux for now and trying to boot bare metal apps that
> calls hypervisor_console_io() at the very beginning of the boot-up. As I'm
> trying to port embedded RTOS apps (both 32 and 64 bits) to run as guests.
>
> Excellent. When doing that kind of work, I find the debug hypercalls very
> useful, see:
>
> xen/arch/arm/traps.c:do_debug_trap
>
> Once you enable DEBUG in the build, you can do
>
> hvc 0xfffd
>
> In the guest for instance to print the program counter.
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