KVM: s390: vsie: support guest-storage-limit-suppression

We can easily forward guest-storage-limit-suppression if available.

One thing to care about is keeping the prefix properly mapped when
gsls in toggled on/off or the mso changes in between. Therefore we better
remap the prefix on any mso changes just like we already do with the
prefix.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

3 files changed, 8 insertions, 2 deletions

diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 98526ac114bf..9ed07479714f 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -102,6 +102,7 @@ struct kvm_s390_vm_cpu_machine {
 #define KVM_S390_VM_CPU_FEAT_64BSCAO    2
 #define KVM_S390_VM_CPU_FEAT_SIIF       3
 #define KVM_S390_VM_CPU_FEAT_GPERE      4
+#define KVM_S390_VM_CPU_FEAT_GSLS       5
 struct kvm_s390_vm_cpu_feat {
         __u64 feat[16];
 };
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 175752877c0d..ce9813afd502 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -271,6 +271,8 @@ static void kvm_s390_cpu_feat_init(void)
                 allow_cpu_feat(KVM_S390_VM_CPU_FEAT_SIIF);
         if (sclp.has_gpere)
                 allow_cpu_feat(KVM_S390_VM_CPU_FEAT_GPERE);
+        if (sclp.has_gsls)
+                allow_cpu_feat(KVM_S390_VM_CPU_FEAT_GSLS);
 }
 
 int kvm_arch_init(void *opaque)
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index b8792ef01030..ea65bf2f0201 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -109,6 +109,8 @@ static int prepare_cpuflags(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
         }
         if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_GPERE))
                 newflags |= cpuflags & CPUSTAT_P;
+        if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_GSLS))
+                newflags |= cpuflags & CPUSTAT_SM;
 
         atomic_set(&scb_s->cpuflags, newflags);
         return 0;
@@ -242,7 +244,7 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
         struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
         struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
         bool had_tx = scb_s->ecb & 0x10U;
-        unsigned long new_mso;
+        unsigned long new_mso = 0;
         int rc;
 
         /* make sure we don't have any leftovers when reusing the scb */
@@ -284,7 +286,8 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
         scb_s->ictl |= ICTL_ISKE | ICTL_SSKE | ICTL_RRBE;
         scb_s->icpua = scb_o->icpua;
 
-        new_mso = scb_o->mso & 0xfffffffffff00000UL;
+        if (!(atomic_read(&scb_s->cpuflags) & CPUSTAT_SM))
+                new_mso = scb_o->mso & 0xfffffffffff00000UL;
         /* if the hva of the prefix changes, we have to remap the prefix */
         if (scb_s->mso != new_mso || scb_s->prefix != scb_o->prefix)
                 prefix_unmapped(vsie_page);