linux-kernel - Re: [tip:x86/microcode] x86/microcode_intel_early.c: Early update ucode on Intel's CPU

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Date:	Fri, 14 Dec 2012 11:46:27 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Borislav Petkov <bp@...en8.de>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	"mingo@...nel.org" <mingo@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"hpa@...ux.intel.com" <hpa@...ux.intel.com>,
	"linux-tip-commits@...r.kernel.org" 
	<linux-tip-commits@...r.kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Stefano Stabellini <Stefano.Stabellini@...citrix.com>
Subject: Re: [tip:x86/microcode] x86/microcode_intel_early.c: Early update
 ucode on Intel's CPU

On 12/14/2012 01:11 AM, Yinghai Lu wrote:
> On Thu, Dec 13, 2012 at 1:36 PM, H. Peter Anvin <hpa@...or.com> wrote:
>>
>> : tazenda 111 ; qemu-kvm -smp 2 -m 2048 -hda ~/qemu/fc10/qemu-fc10-64.img
>> -serial stdio -kernel o.x86_64/arch/x86/boot/bzImage -append 'ro
>> root=/dev/sda1 console=ttyS0 earlyprintk=serial,ttyS0 debug'
>> early console in setup code
>> early console in decompress_kernel
>>
>> [    0.000000] init_memory_mapping: [mem 0x00000000-0x7fffdfff]
>> [    0.000000]  [mem 0x00000000-0x7fdfffff] page 2M
>> [    0.000000]  [mem 0x7fe00000-0x7fffdfff] page 4k
>> [    0.000000] Kernel panic - not syncing: Cannot find space for the kernel
>> page tables
>> [    0.000000] Pid: 0, comm: swapper Not tainted 3.7.0+ #16
>> [    0.000000] Call Trace:
>> [    0.000000]  [<ffffffff817f0d2e>] panic+0xb6/0x1b5
>> [    0.000000]  [<ffffffff817e3801>] init_memory_mapping+0x471/0x5a0
>> [    0.000000]  [<ffffffff81ecd37f>] setup_arch+0x65c/0xb71
>> [    0.000000]  [<ffffffff81ec998e>] start_kernel+0x8a/0x348
>> [    0.000000]  [<ffffffff81ec9452>] x86_64_start_reservations+0x132/0x136
>> [    0.000000]  [<ffffffff81ec94fe>] x86_64_start_kernel+0xa8/0xad
> 
> attached works on kvm local, but SMP does not work yet.
> 
> ON TOP of linus tree + tip:x86/mm2
> 
> I added mapping to kernel to init_level2_mapping with BRK before #PF
> handler still works. (before early_trap_init)
> copy entries into init_level2_page from early_level4_pgt....
> split setup_real_mode to reserve and copy... copy need to after
> init_mem_mapping for system with more than 512G ram.
> 
> my plan is using this one replace
> 
>       [PATCH v6 06/27] x86, 64bit: Set extra ident mapping for whole
> kernel range
> 

That patch doesn't apply on top of the merge of x86/mm2 and
linus/master.  A trivial fixup is totally nonfunctional -- no
earlyprintk, just a null pointer death in setup_real_mode().

I suspect we don't need init_level4_pgt at all and should just plan to
get rid of it.  Is there any reason we can't just build the proper
kernel page table set in pagetable_init() and switch to it there?

	-hpa

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