Hi, On Fri, Feb 03, 2017 at 10:45:39AM +0900, AKASHI Takahiro wrote: > On Thu, Feb 02, 2017 at 11:54:25AM +0000, Mark Rutland wrote: > > On Thu, Feb 02, 2017 at 07:39:06PM +0900, AKASHI Takahiro wrote: > > > On Wed, Feb 01, 2017 at 06:25:06PM +0000, Mark Rutland wrote: > > > > On Wed, Feb 01, 2017 at 06:00:08PM +0000, Mark Rutland wrote: > > > > Another question is (how) does hyp map this region? > > > > > > I don't get your point here. > > > Hyp mode does care only physical memory in intermediate address, doesn't it? > > > > My concern was that hyp may map the region; and thus buggy code at hyp > > can corrupt the region (and/or hyp may conflict w.r.t. attributes). > > Grep'ing create_hyp_mappings() under arch/arm(64)/kvm shows that > we have only a few small regions of memory mapped in hyp mode. > I also confirmed that there is no active mapping for crash dump kernel > memory by checking mmu tables with DS-5 debugger. Ok, that sounds fine. I was under the mistaken impression that hyp had a copy of the whole linear mapping, but it seems it lazily maps that in (at page granularity) as required. So there should be no alias for the crashkernel region. > > We mght have to ensure hyp doesn't map the crashkernel region, and to > > case us pain, disallow freeing of any part of the region. > > So I don't believe we need to worry such a case. I agree. Thanks, Mark.
