Re: [RFC v2 0/5] arm64: kvm: reset hyp context for kexec

From: AKASHI Takahiro
Date: Mon Mar 30 2015 - 04:54:46 EST


On 03/30/2015 04:16 PM, Marc Zyngier wrote:
On Mon, 30 Mar 2015 02:39:53 +0100
AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx> wrote:

On 03/28/2015 02:40 AM, Kyle McMartin wrote:
On Fri, Mar 27, 2015 at 03:37:04PM +0000, Marc Zyngier wrote:
[ 236.260863] Kernel panic - not syncing: HYP panic:
[ 236.260863] PS:600003c9 PC:000003ffffff0830 ESR:0000000096000006

It would be interesting if you could find out what you have at offset
0x830 of hyp-init.o (the stack trace is for EL1, and is not going to
help much).


Given the alignment, i'm going to assume i'm looking at the right thing:

0000000000000820 <__kvm_hyp_reset>:
820: d51c2000 msr ttbr0_el2, x0
824: d5033fdf isb
828: d50c871f tlbi alle2
82c: d5033f9f dsb sy
830: 10000060 adr x0, 83c <__kvm_hyp_reset+0x1c>
834: b3403c01 bfxil x1, x0, #0, #16
838: d61f0020 br x1
83c: d53c1000 mrs x0, sctlr_el2

but it seems fairly implausible to be trapping on ADR x0, 1f...


I've never seen this panic on fast model...

ESR shows that
- Exception class: Data abort taken without a change in Exception level
- Data fault status code: Translation fault at EL2

and FAR seems not to be a proper address.

... which is consistent with what we're seeing here (data fault on
something that doesn't generate a load/store). I'm pretty sure the
page tables are screwed.

Have you tested it with 64k pages?

Hmm... It seems that I was able to reproduce the problem if 64k pages enabled.

-Takahiro AKASHI

Thanks,

M.

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