diff options
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 15 | ||||
| -rw-r--r-- | arch/s390/kvm/kvm-s390.c | 6 | ||||
| -rw-r--r-- | include/uapi/linux/kvm.h | 4 |
3 files changed, 18 insertions, 7 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index f670e4b9e7f3..57d3ee9e4bde 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -2901,14 +2901,19 @@ userspace buffer and its length: struct kvm_s390_irq_state { __u64 buf; - __u32 flags; + __u32 flags; /* will stay unused for compatibility reasons */ __u32 len; - __u32 reserved[4]; + __u32 reserved[4]; /* will stay unused for compatibility reasons */ }; Userspace passes in the above struct and for each pending interrupt a struct kvm_s390_irq is copied to the provided buffer. +The structure contains a flags and a reserved field for future extensions. As +the kernel never checked for flags == 0 and QEMU never pre-zeroed flags and +reserved, these fields can not be used in the future without breaking +compatibility. + If -ENOBUFS is returned the buffer provided was too small and userspace may retry with a bigger buffer. @@ -2932,10 +2937,14 @@ containing a struct kvm_s390_irq_state: struct kvm_s390_irq_state { __u64 buf; + __u32 flags; /* will stay unused for compatibility reasons */ __u32 len; - __u32 pad; + __u32 reserved[4]; /* will stay unused for compatibility reasons */ }; +The restrictions for flags and reserved apply as well. +(see KVM_S390_GET_IRQ_STATE) + The userspace memory referenced by buf contains a struct kvm_s390_irq for each interrupt to be injected into the guest. If one of the interrupts could not be injected for some reason the diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 34375eed93ee..efa439f6ffb3 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -1,8 +1,8 @@ // SPDX-License-Identifier: GPL-2.0 /* - * hosting zSeries kernel virtual machines + * hosting IBM Z kernel virtual machines (s390x) * - * Copyright IBM Corp. 2008, 2009 + * Copyright IBM Corp. 2008, 2017 * * Author(s): Carsten Otte <cotte@de.ibm.com> * Christian Borntraeger <borntraeger@de.ibm.com> @@ -3808,6 +3808,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, r = -EINVAL; break; } + /* do not use irq_state.flags, it will break old QEMUs */ r = kvm_s390_set_irq_state(vcpu, (void __user *) irq_state.buf, irq_state.len); @@ -3823,6 +3824,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, r = -EINVAL; break; } + /* do not use irq_state.flags, it will break old QEMUs */ r = kvm_s390_get_irq_state(vcpu, (__u8 __user *) irq_state.buf, irq_state.len); diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 282d7613fce8..496e59a2738b 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -630,9 +630,9 @@ struct kvm_s390_irq { struct kvm_s390_irq_state { __u64 buf; - __u32 flags; + __u32 flags; /* will stay unused for compatibility reasons */ __u32 len; - __u32 reserved[4]; + __u32 reserved[4]; /* will stay unused for compatibility reasons */ }; /* for KVM_SET_GUEST_DEBUG */ |