From ca09f02f122b2ecb0f5ddfc5fd47b29ed657d4fd Mon Sep 17 00:00:00 2001 From: Marek Majtyka Date: Wed, 16 Sep 2015 12:04:55 +0200 Subject: [PATCH] arm: KVM: Fix incorrect device to IPA mapping A critical bug has been found in device memory stage1 translation for VMs with more then 4GB of address space. Once vm_pgoff size is smaller then pa (which is true for LPAE case, u32 and u64 respectively) some more significant bits of pa may be lost as a shift operation is performed on u32 and later cast onto u64. Example: vm_pgoff(u32)=0x00210030, PAGE_SHIFT=12 expected pa(u64): 0x0000002010030000 produced pa(u64): 0x0000000010030000 The fix is to change the order of operations (casting first onto phys_addr_t and then shifting). Reviewed-by: Marc Zyngier [maz: fixed changelog and patch formatting] Cc: stable@vger.kernel.org Signed-off-by: Marek Majtyka Signed-off-by: Marc Zyngier --- arch/arm/kvm/mmu.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index 7b4201294187..6984342da13d 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -1792,8 +1792,10 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, if (vma->vm_flags & VM_PFNMAP) { gpa_t gpa = mem->guest_phys_addr + (vm_start - mem->userspace_addr); - phys_addr_t pa = (vma->vm_pgoff << PAGE_SHIFT) + - vm_start - vma->vm_start; + phys_addr_t pa; + + pa = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT; + pa += vm_start - vma->vm_start; /* IO region dirty page logging not allowed */ if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES)