arm/arm64: KVM: Check that IDMAP doesn't intersect with VA range (eac378a9) · Commits · 戴 / test

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>

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");

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