After vGIC initialization succeeded, and timer initialization failed, the following crash can be observed on ARM32: kvm [1]: interrupt-controller@10484000 IRQ57 kvm [1]: kvm_arch_timer: can't find DT node Unable to handle kernel paging request at virtual address 90484000 pgd = c0003000 [90484000] *pgd=80000040006003, *pmd=00000000 Internal error: Oops: 2a06 [#1] PREEMPT SMP ARM ... [<c003b790>] (v7_flush_kern_dcache_area) from [<c001d638>] (kvm_flush_dcache_pte+0x48/0x5c) [<c001d638>] (kvm_flush_dcache_pte) from [<c001d898>] (unmap_range+0x24c/0x460) [<c001d898>] (unmap_range) from [<c001ea4c>] (free_hyp_pgds+0x84/0x160) [<c001ea4c>] (free_hyp_pgds) from [<c001c85c>] (kvm_arch_init+0x254/0x41c) [<c001c85c>] (kvm_arch_init) from [<c00122b0>] (kvm_init+0x28/0x2b4) [<c00122b0>] (kvm_init) from [<c0009988>] (do_one_initcall+0x9c/0x200) This happens when unmapping reaches mapped vGIC control registers. The problem root seems to be combination of two facts: 1. vGIC control region is defined in device trees as having size of 0x2000. But the specification defines only registers up to 0x1FC, therefore it is only one page, not two. 2. unmap_ptes() is expected to recognize device memory and omit cache flushing. However, it tests only for PAGE_S2_DEVICE, while devices mapped for HYP mode have PAGE_HYP_DEVICE, which is different. Therefore, cache flush is attempted, and it dies when hitting the nonexistent second page. This patch fixes the problem by adding missing recognition of PAGE_HYP_DEVICE protection value. The crash can be observed on Exynos 5410 (and probably on all Exynos5 family) with stock device trees (using MCT) and CONFIG_KVM enabled. Signed-off-by: Pavel Fedin <p.fedin@xxxxxxxxxxx> --- arch/arm/kvm/mmu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index 7b42012..839dd970 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -213,7 +213,10 @@ static void unmap_ptes(struct kvm *kvm, pmd_t *pmd, kvm_tlb_flush_vmid_ipa(kvm, addr); /* No need to invalidate the cache for device mappings */ - if ((pte_val(old_pte) & PAGE_S2_DEVICE) != PAGE_S2_DEVICE) + if (((pte_val(old_pte) & PAGE_S2_DEVICE) + != PAGE_S2_DEVICE) && + ((pte_val(old_pte) & PAGE_HYP_DEVICE) + != PAGE_HYP_DEVICE)) kvm_flush_dcache_pte(old_pte); put_page(virt_to_page(pte)); -- 2.4.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
