Re: The current SME implementation fails kexec/kdump kernel booting.
From: Baoquan He
Date: Tue Jun 04 2019 - 21:01:25 EST
On 06/04/19 at 03:56pm, Lendacky, Thomas wrote:
> On 6/4/19 8:49 AM, Baoquan He wrote:
> > Hi Tom,
> > Lianbo reported kdump kernel can't boot well with 'nokaslr' added, and
> > have to enable KASLR in kdump kernel to make it boot successfully. This
> > blocked his work on enabling sme for kexec/kdump. And on some machines
> > SME kernel can't boot in 1st kernel.
> > I checked code of SME implementation, and found out the root cause. The
> > above failures are caused by SME code, sme_encrypt_kernel(). In
> > sme_encrypt_kernel(), you get a 2M of encryption work area as intermediate
> > buffer to encrypt kernel in-place. And the work area is just after _end of
> > kernel.
> I remember worrying about something like this back when I was testing the
> kexec support. I had come up with a patch to address it, but never got the
> time to test and submit it. I've included it here if you'd like to test
> it (I haven't done run this patch in quite some time). If it works, we can
> think about submitting it.
Thanks for your quick response and making this patch, Tom.
Tested on a speedway machine, it entered into kernel, but failed in
below stage. Tested two times, always happened.
[ 4.978521] Freeing unused decrypted memory: 2040K
[ 4.983800] Freeing unused kernel image memory: 2344K
[ 4.988943] Write protecting the kernel read-only data: 18432k
[ 4.995306] Freeing unused kernel image memory: 2012K
[ 5.000488] Freeing unused kernel image memory: 256K
[ 5.005540] Run /init as init process
[ 5.009443] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00007f00
[ 5.017230] CPU: 0 PID: 1 Comm: init Not tainted 5.2.0-rc2+ #38
[ 5.023251] Hardware name: AMD Corporation Speedway/Speedway, BIOS RSW1004B 10/18/2017
[ 5.031299] Call Trace:
[ 5.033793] dump_stack+0x46/0x60
[ 5.037169] panic+0xfb/0x2cb
[ 5.040191] do_exit.cold.21+0x59/0x81
[ 5.044004] do_group_exit+0x3a/0xa0
[ 5.047640] __x64_sys_exit_group+0x14/0x20
[ 5.051899] do_syscall_64+0x55/0x1c0
[ 5.055627] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 5.060764] RIP: 0033:0x7fa1b1fc9e2e
[ 5.064404] Code: Bad RIP value.
[ 5.067687] RSP: 002b:00007fffc5abb778 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7
[ 5.075296] RAX: ffffffffffffffda RBX: 00007fa1b1fd2528 RCX: 00007fa1b1fc9e2e
[ 5.082625] RDX: 000000000000007f RSI: 000000000000003c RDI: 000000000000007f
[ 5.089879] RBP: 00007fa1b21d8d00 R08: 00000000000000e7 R09: 00007fffc5abb688
[ 5.097134] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000002
[ 5.104386] R13: 0000000000000001 R14: 00007fa1b21d8d40 R15: 00007fa1b21d8d30
[ 5.111645] Kernel Offset: disabled
[ 5.423002] Rebooting in 10 seconds..
[ 15.429641] ACPI MEMORY or I/O RESET_REG.