From a3a92c31bf0b57ad0ca7f092a6f3a57168ba9ae2 Mon Sep 17 00:00:00 2001 From: Dominik Dingel Date: Mon, 1 Dec 2014 17:24:42 +0100 Subject: [PATCH] KVM: s390: fix mismatch between user and in-kernel guest limit While the userspace interface requests the maximum size the gmap code expects to get a maximum address. This error resulted in bigger page tables than necessary for some guest sizes, e.g. a 2GB guest used 3 levels instead of 2. At the same time we introduce KVM_S390_NO_MEM_LIMIT, which allows in a bright future that a guest spans the complete 64 bit address space. We also switch to TASK_MAX_SIZE for the initial memory size, this is a cosmetic change as the previous size also resulted in a 4 level pagetable creation. Reported-by: David Hildenbrand Reviewed-by: Cornelia Huck Signed-off-by: Dominik Dingel Signed-off-by: Christian Borntraeger --- Documentation/virtual/kvm/devices/vm.txt | 3 ++- arch/s390/include/asm/kvm_host.h | 1 + arch/s390/include/uapi/asm/kvm.h | 2 ++ arch/s390/kvm/kvm-s390.c | 25 +++++++++++++++++++----- arch/s390/mm/pgtable.c | 4 ++-- 5 files changed, 27 insertions(+), 8 deletions(-) diff --git a/Documentation/virtual/kvm/devices/vm.txt b/Documentation/virtual/kvm/devices/vm.txt index 2d09d1ed86d0..f083a168eb35 100644 --- a/Documentation/virtual/kvm/devices/vm.txt +++ b/Documentation/virtual/kvm/devices/vm.txt @@ -37,7 +37,8 @@ Returns: -EFAULT if the given address is not accessible Allows userspace to query the actual limit and set a new limit for the maximum guest memory size. The limit will be rounded up to 2048 MB, 4096 GB, 8192 TB respectively, as this limit is governed by -the number of page table levels. +the number of page table levels. In the case that there is no limit we will set +the limit to KVM_S390_NO_MEM_LIMIT (U64_MAX). 2. GROUP: KVM_S390_VM_CPU_MODEL Architectures: s390 diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index 12e9291da267..c83144110ea9 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -627,6 +627,7 @@ struct kvm_arch{ struct kvm_s390_float_interrupt float_int; struct kvm_device *flic; struct gmap *gmap; + unsigned long mem_limit; int css_support; int use_irqchip; int use_cmma; diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h index ef1a5fcc6c66..d2aea31252f2 100644 --- a/arch/s390/include/uapi/asm/kvm.h +++ b/arch/s390/include/uapi/asm/kvm.h @@ -66,6 +66,8 @@ struct kvm_s390_io_adapter_req { #define KVM_S390_VM_MEM_CLR_CMMA 1 #define KVM_S390_VM_MEM_LIMIT_SIZE 2 +#define KVM_S390_NO_MEM_LIMIT U64_MAX + /* kvm attributes for KVM_S390_VM_TOD */ #define KVM_S390_VM_TOD_LOW 0 #define KVM_S390_VM_TOD_HIGH 1 diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index c14845c3a6f8..8aa5e55a8ecd 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -378,8 +378,8 @@ static int kvm_s390_get_mem_control(struct kvm *kvm, struct kvm_device_attr *att case KVM_S390_VM_MEM_LIMIT_SIZE: ret = 0; VM_EVENT(kvm, 3, "QUERY: max guest memory: %lu bytes", - kvm->arch.gmap->asce_end); - if (put_user(kvm->arch.gmap->asce_end, (u64 __user *)attr->addr)) + kvm->arch.mem_limit); + if (put_user(kvm->arch.mem_limit, (u64 __user *)attr->addr)) ret = -EFAULT; break; default: @@ -431,9 +431,17 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att if (get_user(new_limit, (u64 __user *)attr->addr)) return -EFAULT; - if (new_limit > kvm->arch.gmap->asce_end) + if (kvm->arch.mem_limit != KVM_S390_NO_MEM_LIMIT && + new_limit > kvm->arch.mem_limit) return -E2BIG; + if (!new_limit) + return -EINVAL; + + /* gmap_alloc takes last usable address */ + if (new_limit != KVM_S390_NO_MEM_LIMIT) + new_limit -= 1; + ret = -EBUSY; mutex_lock(&kvm->lock); if (atomic_read(&kvm->online_vcpus) == 0) { @@ -450,7 +458,9 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att } } mutex_unlock(&kvm->lock); - VM_EVENT(kvm, 3, "SET: max guest memory: %lu bytes", new_limit); + VM_EVENT(kvm, 3, "SET: max guest address: %lu", new_limit); + VM_EVENT(kvm, 3, "New guest asce: 0x%pK", + (void *) kvm->arch.gmap->asce); break; } default: @@ -1172,8 +1182,10 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) if (type & KVM_VM_S390_UCONTROL) { kvm->arch.gmap = NULL; + kvm->arch.mem_limit = KVM_S390_NO_MEM_LIMIT; } else { - kvm->arch.gmap = gmap_alloc(current->mm, (1UL << 44) - 1); + kvm->arch.mem_limit = TASK_MAX_SIZE; + kvm->arch.gmap = gmap_alloc(current->mm, kvm->arch.mem_limit - 1); if (!kvm->arch.gmap) goto out_err; kvm->arch.gmap->private = kvm; @@ -2829,6 +2841,9 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, if (mem->memory_size & 0xffffful) return -EINVAL; + if (mem->guest_phys_addr + mem->memory_size > kvm->arch.mem_limit) + return -EINVAL; + return 0; } diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 54ef3bc01b43..63b039899a5e 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -133,7 +133,7 @@ void crst_table_downgrade(struct mm_struct *mm, unsigned long limit) /** * gmap_alloc - allocate a guest address space * @mm: pointer to the parent mm_struct - * @limit: maximum size of the gmap address space + * @limit: maximum address of the gmap address space * * Returns a guest address space structure. */ @@ -402,7 +402,7 @@ int gmap_map_segment(struct gmap *gmap, unsigned long from, if ((from | to | len) & (PMD_SIZE - 1)) return -EINVAL; if (len == 0 || from + len < from || to + len < to || - from + len > TASK_MAX_SIZE || to + len > gmap->asce_end) + from + len - 1 > TASK_MAX_SIZE || to + len - 1 > gmap->asce_end) return -EINVAL; flush = 0; -- 2.20.1