From 75a4615c95a2de4fa592c1312fb8446e74b4e5eb Mon Sep 17 00:00:00 2001 From: Julius Niedworok Date: Wed, 3 Aug 2016 16:39:54 +0200 Subject: [PATCH 1/2] KVM: s390: set the prefix initially properly When KVM_RUN is triggered on a VCPU without an initial reset, a validity intercept occurs. Setting the prefix will set the KVM_REQ_MMU_RELOAD bit initially, thus preventing the bug. Reviewed-by: David Hildenbrand Acked-by: Cornelia Huck Signed-off-by: Julius Niedworok Signed-off-by: Christian Borntraeger --- arch/s390/kvm/kvm-s390.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 3f3ae4865d57..e63f6ed0a936 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -1672,6 +1672,7 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) KVM_SYNC_CRS | KVM_SYNC_ARCH0 | KVM_SYNC_PFAULT; + kvm_s390_set_prefix(vcpu, 0); if (test_kvm_facility(vcpu->kvm, 64)) vcpu->run->kvm_valid_regs |= KVM_SYNC_RICCB; /* fprs can be synchronized via vrs, even if the guest has no vx. With From aca411a4b17a4aebe14ecdf253373db5b7ee6058 Mon Sep 17 00:00:00 2001 From: Julius Niedworok Date: Wed, 3 Aug 2016 16:39:55 +0200 Subject: [PATCH 2/2] KVM: s390: reset KVM_REQ_MMU_RELOAD if mapping the prefix failed When triggering KVM_RUN without a user memory region being mapped (KVM_SET_USER_MEMORY_REGION) a validity intercept occurs. This could happen, if the user memory region was not mapped initially or if it was unmapped after the vcpu is initialized. The function kvm_s390_handle_requests checks for the KVM_REQ_MMU_RELOAD bit. The check function always clears this bit. If gmap_mprotect_notify returns an error code, the mapping failed, but the KVM_REQ_MMU_RELOAD was not set anymore. So the next time kvm_s390_handle_requests is called, the execution would fall trough the check for KVM_REQ_MMU_RELOAD. The bit needs to be resetted, if gmap_mprotect_notify returns an error code. Resetting the bit with kvm_make_request(KVM_REQ_MMU_RELOAD, vcpu) fixes the bug. Reviewed-by: David Hildenbrand Signed-off-by: Julius Niedworok Signed-off-by: Christian Borntraeger --- arch/s390/kvm/kvm-s390.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index e63f6ed0a936..f142215ed30d 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -2362,8 +2362,10 @@ retry: rc = gmap_mprotect_notify(vcpu->arch.gmap, kvm_s390_get_prefix(vcpu), PAGE_SIZE * 2, PROT_WRITE); - if (rc) + if (rc) { + kvm_make_request(KVM_REQ_MMU_RELOAD, vcpu); return rc; + } goto retry; }