From 0dd4cdccdab3d74bd86b868768a7dca216bcce7e Mon Sep 17 00:00:00 2001 From: Thomas Huth Date: Wed, 23 Nov 2022 10:08:33 +0100 Subject: KVM: s390: vsie: Fix the initialization of the epoch extension (epdx) field We recently experienced some weird huge time jumps in nested guests when rebooting them in certain cases. After adding some debug code to the epoch handling in vsie.c (thanks to David Hildenbrand for the idea!), it was obvious that the "epdx" field (the multi-epoch extension) did not get set to 0xff in case the "epoch" field was negative. Seems like the code misses to copy the value from the epdx field from the guest to the shadow control block. By doing so, the weird time jumps are gone in our scenarios. Link: https://bugzilla.redhat.com/show_bug.cgi?id=2140899 Fixes: 8fa1696ea781 ("KVM: s390: Multiple Epoch Facility support") Signed-off-by: Thomas Huth Reviewed-by: Christian Borntraeger Acked-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Reviewed-by: Janosch Frank Cc: stable@vger.kernel.org # 4.19+ Link: https://lore.kernel.org/r/20221123090833.292938-1-thuth@redhat.com Message-Id: <20221123090833.292938-1-thuth@redhat.com> Signed-off-by: Janosch Frank --- arch/s390/kvm/vsie.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c index 94138f8f0c1c..ace2541ababd 100644 --- a/arch/s390/kvm/vsie.c +++ b/arch/s390/kvm/vsie.c @@ -546,8 +546,10 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_CEI)) scb_s->eca |= scb_o->eca & ECA_CEI; /* Epoch Extension */ - if (test_kvm_facility(vcpu->kvm, 139)) + if (test_kvm_facility(vcpu->kvm, 139)) { scb_s->ecd |= scb_o->ecd & ECD_MEF; + scb_s->epdx = scb_o->epdx; + } /* etoken */ if (test_kvm_facility(vcpu->kvm, 156)) -- cgit v1.2.3 From e542baf30b48605d4336bf54b98e76b8fb98af30 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 30 Nov 2022 11:14:35 -0500 Subject: KVM: x86: fix uninitialized variable use on KVM_REQ_TRIPLE_FAULT If a triple fault was fixed by kvm_x86_ops.nested_ops->triple_fault (by turning it into a vmexit), there is no need to leave vcpu_enter_guest(). Any vcpu->requests will be caught later before the actual vmentry, and in fact vcpu_enter_guest() was not initializing the "r" variable. Depending on the compiler's whims, this could cause the x86_64/triple_fault_event_test test to fail. Cc: Maxim Levitsky Fixes: 92e7d5c83aff ("KVM: x86: allow L1 to not intercept triple fault") Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 2835bd796639..69227f77b201 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10574,8 +10574,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) vcpu->run->exit_reason = KVM_EXIT_SHUTDOWN; vcpu->mmio_needed = 0; r = 0; + goto out; } - goto out; } if (kvm_check_request(KVM_REQ_APF_HALT, vcpu)) { /* Page is swapped out. Do synthetic halt */ -- cgit v1.2.3