From 7119decf47d9867266459615be502e5d2cecedba Mon Sep 17 00:00:00 2001 From: Janis Schoetterl-Glausch Date: Tue, 29 Jun 2021 10:55:30 +0200 Subject: [PATCH] KVM: s390: Enable specification exception interpretation When this feature is enabled the hardware is free to interpret specification exceptions generated by the guest, instead of causing program interruption interceptions. This benefits (test) programs that generate a lot of specification exceptions (roughly 4x increase in exceptions/sec). Interceptions will occur as before if ICTL_PINT is set, i.e. if guest debug is enabled. There is no indication if this feature is available or not and the hardware is free to interpret or not. So we can simply set this bit and if the hardware ignores it we fall back to intercept 8 handling. Signed-off-by: Janis Schoetterl-Glausch Link: https://lore.kernel.org/linux-s390/20210706114714.3936825-1-scgl@linux.ibm.com/ Reviewed-by: David Hildenbrand Reviewed-by: Christian Borntraeger Signed-off-by: Christian Borntraeger --- arch/s390/include/asm/kvm_host.h | 1 + arch/s390/kvm/kvm-s390.c | 2 ++ arch/s390/kvm/vsie.c | 2 ++ 3 files changed, 5 insertions(+) diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index 8925f3969478..118d5450c523 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -244,6 +244,7 @@ struct kvm_s390_sie_block { __u8 fpf; /* 0x0060 */ #define ECB_GS 0x40 #define ECB_TE 0x10 +#define ECB_SPECI 0x08 #define ECB_SRSI 0x04 #define ECB_HOSTPROTINT 0x02 __u8 ecb; /* 0x0061 */ diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index f72f361d39dd..5b45c83ced21 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3180,6 +3180,8 @@ static int kvm_s390_vcpu_setup(struct kvm_vcpu *vcpu) vcpu->arch.sie_block->ecb |= ECB_SRSI; if (test_kvm_facility(vcpu->kvm, 73)) vcpu->arch.sie_block->ecb |= ECB_TE; + if (!kvm_is_ucontrol(vcpu->kvm)) + vcpu->arch.sie_block->ecb |= ECB_SPECI; if (test_kvm_facility(vcpu->kvm, 8) && vcpu->kvm->arch.use_pfmfi) vcpu->arch.sie_block->ecb2 |= ECB2_PFMFI; diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c index 4002a24bc43a..acda4b6fc851 100644 --- a/arch/s390/kvm/vsie.c +++ b/arch/s390/kvm/vsie.c @@ -510,6 +510,8 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) prefix_unmapped(vsie_page); scb_s->ecb |= ECB_TE; } + /* specification exception interpretation */ + scb_s->ecb |= scb_o->ecb & ECB_SPECI; /* branch prediction */ if (test_kvm_facility(vcpu->kvm, 82)) scb_s->fpf |= scb_o->fpf & FPF_BPBC; -- 2.11.0