From eac378a9ceb7196b776a965d915e02995fb8ba55 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 30 Jun 2016 18:40:50 +0100 Subject: [PATCH] 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 Signed-off-by: Christoffer Dall --- 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 0b36dd52af62..8a0aa37605c5 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -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");