From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Subject: Re: [PATCH v3 2/2] arm/arm64: KVM: Support KVM_CAP_READONLY_MEM Date: Tue, 26 Aug 2014 16:26:59 +0100 Message-ID: <53FCA743.5020000@arm.com> References: <1409053393-13768-1-git-send-email-christoffer.dall@linaro.org> <1409053393-13768-2-git-send-email-christoffer.dall@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: "kvmarm@lists.cs.columbia.edu" , "linux-arm-kernel@lists.infradead.org" , "kvm@vger.kernel.org" , Peter Maydell , Ard Biesheuvel To: Christoffer Dall Return-path: Received: from fw-tnat.austin.arm.com ([217.140.110.23]:45951 "EHLO collaborate-mta1.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751843AbaHZP1H (ORCPT ); Tue, 26 Aug 2014 11:27:07 -0400 In-Reply-To: <1409053393-13768-2-git-send-email-christoffer.dall@linaro.org> Sender: kvm-owner@vger.kernel.org List-ID: On 26/08/14 12:43, Christoffer Dall wrote: > When userspace loads code and data in a read-only memory regions, KVM > needs to be able to handle this on arm and arm64. Specifically this is > used when running code directly from a read-only flash device; the > common scenario is a UEFI blob loaded with the -bios option in QEMU. > > Note that the MMIO exit on writes to a read-only memory is ABI and can > be used to emulate block-erase style flash devices. > > Cc: Ard Biesheuvel > Signed-off-by: Christoffer Dall Acked-by: Marc Zyngier M. > --- > Changelog[v3]: > - Remove the check for fault_status != FSC_FAULT in the I/O memory > abort section, since we now do support permission faults on I/O > regions. Reported-by: Ard Biesheuvel > Changelog[v2]: > - None > > arch/arm/include/uapi/asm/kvm.h | 1 + > arch/arm/kvm/arm.c | 1 + > arch/arm/kvm/mmu.c | 22 ++++++++-------------- > arch/arm64/include/uapi/asm/kvm.h | 1 + > 4 files changed, 11 insertions(+), 14 deletions(-) > > diff --git a/arch/arm/include/uapi/asm/kvm.h b/arch/arm/include/uapi/asm/kvm.h > index e6ebdd3..51257fd 100644 > --- a/arch/arm/include/uapi/asm/kvm.h > +++ b/arch/arm/include/uapi/asm/kvm.h > @@ -25,6 +25,7 @@ > > #define __KVM_HAVE_GUEST_DEBUG > #define __KVM_HAVE_IRQ_LINE > +#define __KVM_HAVE_READONLY_MEM > > #define KVM_REG_SIZE(id) \ > (1U << (((id) & KVM_REG_SIZE_MASK) >> KVM_REG_SIZE_SHIFT)) > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index 9f788eb..ac306b4 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -188,6 +188,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > case KVM_CAP_ONE_REG: > case KVM_CAP_ARM_PSCI: > case KVM_CAP_ARM_PSCI_0_2: > + case KVM_CAP_READONLY_MEM: > r = 1; > break; > case KVM_CAP_COALESCED_MMIO: > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c > index 16e7994..62f5642 100644 > --- a/arch/arm/kvm/mmu.c > +++ b/arch/arm/kvm/mmu.c > @@ -747,14 +747,13 @@ static bool transparent_hugepage_adjust(pfn_t *pfnp, phys_addr_t *ipap) > } > > static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > - struct kvm_memory_slot *memslot, > + struct kvm_memory_slot *memslot, unsigned long hva, > unsigned long fault_status) > { > int ret; > bool write_fault, writable, hugetlb = false, force_pte = false; > unsigned long mmu_seq; > gfn_t gfn = fault_ipa >> PAGE_SHIFT; > - unsigned long hva = gfn_to_hva(vcpu->kvm, gfn); > struct kvm *kvm = vcpu->kvm; > struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache; > struct vm_area_struct *vma; > @@ -863,7 +862,8 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run) > unsigned long fault_status; > phys_addr_t fault_ipa; > struct kvm_memory_slot *memslot; > - bool is_iabt; > + unsigned long hva; > + bool is_iabt, write_fault, writable; > gfn_t gfn; > int ret, idx; > > @@ -884,7 +884,10 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run) > idx = srcu_read_lock(&vcpu->kvm->srcu); > > gfn = fault_ipa >> PAGE_SHIFT; > - if (!kvm_is_visible_gfn(vcpu->kvm, gfn)) { > + memslot = gfn_to_memslot(vcpu->kvm, gfn); > + hva = gfn_to_hva_memslot_prot(memslot, gfn, &writable); > + write_fault = kvm_is_write_fault(kvm_vcpu_get_hsr(vcpu)); > + if (kvm_is_error_hva(hva) || (write_fault && !writable)) { > if (is_iabt) { > /* Prefetch Abort on I/O address */ > kvm_inject_pabt(vcpu, kvm_vcpu_get_hfar(vcpu)); > @@ -892,13 +895,6 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run) > goto out_unlock; > } > > - if (fault_status != FSC_FAULT) { > - kvm_err("Unsupported fault status on io memory: %#lx\n", > - fault_status); > - ret = -EFAULT; > - goto out_unlock; > - } > - > /* > * The IPA is reported as [MAX:12], so we need to > * complement it with the bottom 12 bits from the > @@ -910,9 +906,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run) > goto out_unlock; > } > > - memslot = gfn_to_memslot(vcpu->kvm, gfn); > - > - ret = user_mem_abort(vcpu, fault_ipa, memslot, fault_status); > + ret = user_mem_abort(vcpu, fault_ipa, memslot, hva, fault_status); > if (ret == 0) > ret = 1; > out_unlock: > diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h > index e633ff8..f4ec5a6 100644 > --- a/arch/arm64/include/uapi/asm/kvm.h > +++ b/arch/arm64/include/uapi/asm/kvm.h > @@ -37,6 +37,7 @@ > > #define __KVM_HAVE_GUEST_DEBUG > #define __KVM_HAVE_IRQ_LINE > +#define __KVM_HAVE_READONLY_MEM > > #define KVM_REG_SIZE(id) \ > (1U << (((id) & KVM_REG_SIZE_MASK) >> KVM_REG_SIZE_SHIFT)) > -- Jazz is not dead. It just smells funny...