Re: [Qemu-devel] Re: Unusual physical address when using 64-bit BAR

[Cam Macdonell <cam@cs.ualberta.ca>]

On Tue, Jul 13, 2010 at 2:41 PM, Isaku Yamahata <yamahata@valinux.co.jp> wrote:
> On Tue, Jul 13, 2010 at 02:05:51PM -0600, Cam Macdonell wrote:
>> >> > Seabios completely ignore the 64-bitness of the BAR. ?Looks like it also
>> >> > thinks the second half of the BAR is an I/O region instead of memory (hence
>> >> > the c200, that's part of the pci portio region.
>> >
>> > I've sent the patches to address it. But they haven't been merged yet.
>> > seabios doesn't map BARs beyond 4GB.
>> > If bar is mapped beyond 4GB, guest BIOS does it.
>>
>> Have those patches been merged yet?
>
> They have been merged into seabios upstream now.
> qemu seabios fork hasn't pulled for a while, though.
>
>
>> > To see how seabios works, it would help to increase CONFIG_DEBUG_LEVEL
>> > in config.h of seabios
>>
>> Where does the output from seabios end up?  Inside dmesg?
>
> It outputs them to the serial console which qemu emulates.
> seabios is out of kernel control, so dmesg doesn't show it.
>
>
>> >> pci_read_config: (val) 0x0 <- 0x1c (addr)
>> >> pci_write_config: (val) 0x0 -> 0x1c (addr)
>> >> pci_read_config: (val) 0xffffffff <- 0x1c (addr)
>> >> pci_write_config: (val) 0x0 -> 0x1c (addr)
>> >> pci_read_config: (val) 0x0 <- 0x1c (addr)
>> >> pci_write_config: (val) 0x0 -> 0x1c (addr)
>> >
>> > seabios BAR3. Not sure how it is mapped from this
>> > message.
>>
>> Isn't the BAR3 from the fact that a 64-bit BAR would use both BAR2 and
>> BAR3 to store all 64-bits?
>
> Yes. Seabios misbehaves. 64bit bar is(was) a missing feature.
> --
> yamahata
>
>

With the latest seabios git passed via -bios, I no longer see the
48-bit address, but instead a 32-bit address and then
ffffffff00000000.  This guest has 1gb of RAM so the address isn't be
mapped beyond 4g.

IVSHMEM: guest pci addr = e0000000, guest h/w addr = 1090912256, size = 20000000
IVSHMEM: guest pci addr = ffffffff00000000, guest h/w addr =
1090912256, size = 20000000

However, booting fails when I use a 64-bit BAR.  Booting is fine with
a 32-bit BAR.

HPET: 1 timers in total, 0 timers will be used for per-cpu timer
divide error: 0000 [#1] SMP last sysfs file:
CPU 0
Modules linked in:

Pid: 1, comm: swapper Not tainted 2.6.35-rc1 #280 /Bochs
RIP: 0010:[<ffffffff812a801b>]  [<ffffffff812a801b>] hpet_alloc+0x12c/0x35b
RSP: 0018:ffff88003e61fd80  EFLAGS: 00010246
RAX: 00038d7ea4c68000 RBX: ffff88003e6efd80 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff817b8520
RBP: ffff88003e61fdc0 R08: 00000000000080d0 R09: ffffc90000000000
R10: ffff88003f9ac600 R11: 0000000000000000 R12: ffff88003e61fdd0
R13: ffffc90000000000 R14: 0000000000000000 R15: ffffffff817a00a9
FS:  0000000000000000(0000) GS:ffff880002000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000000 CR3: 0000000001a42000 CR4: 00000000000006f0DR0:
0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process swapper (pid: 1, threadinfo ffff88003e61e000, task ffff88003e620000)
Stack:
 ffff88003f43ab90 ffff88003f43ab90 ffffffff81ca3174 ffffffff81b1d596
<0> 0000000000000000 0000000000000100 0000000000000100 0000000000000000
<0> ffff88003e61fe80 ffffffff8102945d 00000000fed00000 ffffc90000000000
Call Trace:
 [<ffffffff81b1d596>] ? hpet_late_init+0x0/0xea
 [<ffffffff8102945d>] hpet_reserve_platform_timers+0x10b/0x115
 [<ffffffff81b1d596>] ? hpet_late_init+0x0/0xea
 [<ffffffff81b1d601>] hpet_late_init+0x6b/0xea
 [<ffffffff81b1d596>] ? hpet_late_init+0x0/0xea
 [<ffffffff81002069>] do_one_initcall+0x5e/0x159
 [<ffffffff81b0b71e>] kernel_init+0x18e/0x21c
 [<ffffffff8100aa24>] kernel_thread_helper+0x4/0x10
 [<ffffffff81b0b590>] ? kernel_init+0x0/0x21c
 [<ffffffff8100aa20>] ? kernel_thread_helper+0x0/0x10
Code: 89 1d 8a 92 b3 00 48 c1 ea 21 8b 73 34 49 c7 c7 a9 00 7a 81 48
8d 04 02 4c 89 f2 48 c7 c7 20 85 7b 81 48 c1 ea 20 48 89 d1 31 d2 <48>
f7 f1 83 7b 30 01 48
c7 c1 cd fa 7c 81 49 0f 46 cf 48 89 43
RIP  [<ffffffff812a801b>] hpet_alloc+0x12c/0x35b
 RSP <ffff88003e61fd80>
---[ end trace a7919e7f17c0a725 ]---
Kernel panic - not syncing: Attempted to kill init!
Pid: 1, comm: swapper Tainted: G      D     2.6.35-rc1 #280
Call Trace:
 [<ffffffff8145b870>] panic+0x8b/0x10b
 [<ffffffff81056a93>] ? exit_ptrace+0x38/0x121
 [<ffffffff8104f9e8>] do_exit+0x7a/0x722
 [<ffffffff8104c3bd>] ? spin_unlock_irqrestore+0xe/0x10
 [<ffffffff8104cfd8>] ? kmsg_dump+0x12b/0x145
 [<ffffffff8145eaa9>] oops_end+0xbf/0xc7
 [<ffffffff8100d299>] die+0x5a/0x63
 [<ffffffff8145e4b3>] do_trap+0x121/0x130
 [<ffffffff8100b560>] do_divide_error+0x96/0x9f
 [<ffffffff812a801b>] ? hpet_alloc+0x12c/0x35b
 [<ffffffff8100a83b>] divide_error+0x1b/0x20
 [<ffffffff812a801b>] ? hpet_alloc+0x12c/0x35b
 [<ffffffff81b1d596>] ? hpet_late_init+0x0/0xea
 [<ffffffff8102945d>] hpet_reserve_platform_timers+0x10b/0x115
 [<ffffffff81b1d596>] ? hpet_late_init+0x0/0xea
 [<ffffffff81b1d601>] hpet_late_init+0x6b/0xea
 [<ffffffff81b1d596>] ? hpet_late_init+0x0/0xea
 [<ffffffff81002069>] do_one_initcall+0x5e/0x159
 [<ffffffff81b0b71e>] kernel_init+0x18e/0x21c
 [<ffffffff8100aa24>] kernel_thread_helper+0x4/0x10
 [<ffffffff81b0b590>] ? kernel_init+0x0/0x21c
 [<ffffffff8100aa20>] ? kernel_thread_helper+0x0/0x10