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Commit eac378a9 authored by Marc Zyngier's avatar Marc Zyngier Committed by Christoffer Dall
Browse files

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: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
parent f7bec68d

arch/arm/kvm/mmu.c

+15 −0
Original line number Diff line number Diff line
@@ -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");