From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:35614 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753960AbbEKLTc (ORCPT ); Mon, 11 May 2015 07:19:32 -0400 From: Sasha Levin To: stable@vger.kernel.org, stable-commits@vger.kernel.org Cc: Ard Biesheuvel , Marc Zyngier , Shannon Zhao , Sasha Levin Subject: [added to the 3.18 stable tree] arm, arm64: KVM: handle potential incoherency of readonly memslots Date: Mon, 11 May 2015 07:16:24 -0400 Message-Id: <1431343152-19437-3-git-send-email-sasha.levin@oracle.com> In-Reply-To: <1431343152-19437-1-git-send-email-sasha.levin@oracle.com> References: <1431343152-19437-1-git-send-email-sasha.levin@oracle.com> Sender: stable-owner@vger.kernel.org List-ID: From: Ard Biesheuvel commit 849260c72c6b8bd53850cb00b80027db3a273c2c upstream. Readonly memslots are often used to implement emulation of ROMs and NOR flashes, in which case the guest may legally map these regions as uncached. To deal with the incoherency associated with uncached guest mappings, treat all readonly memslots as incoherent, and ensure that pages that belong to regions tagged as such are flushed to DRAM before being passed to the guest. Signed-off-by: Ard Biesheuvel Signed-off-by: Marc Zyngier Signed-off-by: Shannon Zhao Signed-off-by: Sasha Levin --- arch/arm/kvm/mmu.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index 8038e52..16ae5f0 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -920,7 +920,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, if (!hugetlb && !force_pte) hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa); - fault_ipa_uncached = false; + fault_ipa_uncached = memslot->flags & KVM_MEMSLOT_INCOHERENT; if (hugetlb) { pmd_t new_pmd = pfn_pmd(pfn, mem_type); @@ -1299,11 +1299,12 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, hva = vm_end; } while (hva < reg_end); - if (ret) { - spin_lock(&kvm->mmu_lock); + spin_lock(&kvm->mmu_lock); + if (ret) unmap_stage2_range(kvm, mem->guest_phys_addr, mem->memory_size); - spin_unlock(&kvm->mmu_lock); - } + else + stage2_flush_memslot(kvm, memslot); + spin_unlock(&kvm->mmu_lock); return ret; } @@ -1315,6 +1316,15 @@ void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free, int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot, unsigned long npages) { + /* + * Readonly memslots are not incoherent with the caches by definition, + * but in practice, they are used mostly to emulate ROMs or NOR flashes + * that the guest may consider devices and hence map as uncached. + * To prevent incoherency issues in these cases, tag all readonly + * regions as incoherent. + */ + if (slot->flags & KVM_MEM_READONLY) + slot->flags |= KVM_MEMSLOT_INCOHERENT; return 0; } -- 2.1.0