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arm/arm64: KVM: Check that IDMAP doesn't intersect with VA range 

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.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This commit is contained in:
Marc Zyngier 2016-06-30 18:40:50 +01:00 committed by Christoffer Dall
parent f7bec68d2f
commit eac378a9ce
1 changed files with 15 additions and 0 deletions
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15
arch/arm/kvm/mmu.c
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@ -1709,6 +1709,21 @@ 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)) {
/*
* 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");