On Tue, Jun 07, 2016 at 11:58:35AM +0100, Marc Zyngier wrote: > This is more of a safety measure than anything else: If we end-up > with an idmap page that intersect with the range picked for the > the HYP VA space, abort the KVM setup, as it is unsafe to go > further. > > I cannot imagine it happening on 64bit (we have a mechanism to > work around it), but could potentially occur on a 32bit system with > the kernel loaded high enough in memory so that in conflicts with > the kernel VA.
ah, you had a patch for this... does this even work for enabling the MMU during kernel boot or how do they deal with it? > > Signed-off-by: Marc Zyngier <[email protected]> > --- > arch/arm/kvm/mmu.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c > index 46b8604..819517d 100644 > --- a/arch/arm/kvm/mmu.c > +++ b/arch/arm/kvm/mmu.c > @@ -1708,6 +1708,21 @@ int kvm_mmu_init(void) > */ > BUG_ON((hyp_idmap_start ^ (hyp_idmap_end - 1)) & PAGE_MASK); > > + kvm_info("IDMAP page: %lx\n", hyp_idmap_start); > + kvm_info("HYP VA range: %lx:%lx\n", > + KERN_TO_HYP(PAGE_OFFSET), KERN_TO_HYP(~0UL)); > + > + if (hyp_idmap_start >= KERN_TO_HYP(PAGE_OFFSET) && > + hyp_idmap_start < KERN_TO_HYP(~0UL)) { why is the second part of this clause necessary? > + /* > + * The idmap page is intersecting with the VA space, > + * it is not safe to continue further. > + */ > + kvm_err("IDMAP intersecting with HYP VA, unable to continue\n"); > + err = -EINVAL; > + goto out; > + } > + > hyp_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, > hyp_pgd_order); > if (!hyp_pgd) { > kvm_err("Hyp mode PGD not allocated\n"); > -- > 2.1.4 > Thanks, -Christoffer _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
