[PATCH 02/27] arm/arm64: KVM: Support KVM_CAP_READONLY_MEM
From: Christoffer Dall <hidden>
Date: 2014-09-26 13:16:35
Also in:
kvm
Subsystem:
arm port, arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Russell King, Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
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. Acked-by: Marc Zyngier <redacted> Signed-off-by: Christoffer Dall <redacted> --- 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))
--
2.0.0