mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-08-26 10:49:33 +00:00
Code Issues Releases Wiki Activity

KVM: s390: Enable specification exception interpretation

Browse source 
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>
This commit is contained in:
Janis Schoetterl-Glausch 2021-06-29 10:55:30 +02:00 committed by Christian Borntraeger
parent 1f703d2cf2
commit 7119decf47
3 changed files with 5 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
arch/s390/include/asm/kvm_host.h
View file

@ -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 */

2
arch/s390/kvm/kvm-s390.c
View file

@ -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;

2
arch/s390/kvm/vsie.c
View file

@ -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;