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authorJanis Schoetterl-Glausch <scgl@linux.ibm.com>2021-06-29 11:55:30 +0300
committerChristian Borntraeger <borntraeger@de.ibm.com>2021-08-27 19:35:20 +0300
commit7119decf47d9867266459615be502e5d2cecedba (patch)
treeaf9d76e4525e2be6fdf33853336a7bfe32e6a4e7
parent1f703d2cf20464338c3d5279dddfb65ac79b8782 (diff)
downloadlinux-7119decf47d9867266459615be502e5d2cecedba.tar.xz
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 <scgl@linux.ibm.com> Link: https://lore.kernel.org/linux-s390/20210706114714.3936825-1-scgl@linux.ibm.com/ Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
-rw-r--r--arch/s390/include/asm/kvm_host.h1
-rw-r--r--arch/s390/kvm/kvm-s390.c2
-rw-r--r--arch/s390/kvm/vsie.c2
3 files changed, 5 insertions, 0 deletions
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;