KVM: s390: Don't enable skeys by default

The first invocation of storage key operations on a given cpu will be intercepted.

On these intercepts we will enable storage keys for the guest and remove the
previously added intercepts.

Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

5 files changed, 33 insertions, 1 deletions

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 154b60089be9..a993b6f3429f 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -89,6 +89,9 @@ struct kvm_s390_sie_block {
         __u16   lctl;                   /* 0x0044 */
         __s16   icpua;                  /* 0x0046 */
 #define ICTL_LPSW 0x00400000
+#define ICTL_ISKE 0x00004000
+#define ICTL_SSKE 0x00002000
+#define ICTL_RRBE 0x00001000
         __u32   ictl;                   /* 0x0048 */
         __u32   eca;                    /* 0x004c */
         __u8    icptcode;               /* 0x0050 */
diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index 05925ead0748..d42fb1b728d8 100644
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -23,7 +23,7 @@ static inline int init_new_context(struct task_struct *tsk,
         mm->context.asce_bits |= _ASCE_TYPE_REGION3;
 #endif
         mm->context.has_pgste = 0;
-        mm->context.use_skey = 1;
+        mm->context.use_skey = 0;
         mm->context.asce_limit = STACK_TOP_MAX;
         crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
         return 0;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index b3ecb8f5b6ce..b767ec97368a 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -465,6 +465,7 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
         vcpu->arch.sie_block->ecb2  = 8;
         vcpu->arch.sie_block->eca   = 0xC1002001U;
         vcpu->arch.sie_block->fac   = (int) (long) vfacilities;
+        vcpu->arch.sie_block->ictl |= ICTL_ISKE | ICTL_SSKE | ICTL_RRBE;
         if (kvm_enabled_cmma()) {
                 cbrl = alloc_page(GFP_KERNEL | __GFP_ZERO);
                 if (cbrl) {
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 476e9e218f43..8a63e992936b 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -147,8 +147,21 @@ static int handle_store_cpu_address(struct kvm_vcpu *vcpu)
         return 0;
 }
 
+static void __skey_check_enable(struct kvm_vcpu *vcpu)
+{
+        if (!(vcpu->arch.sie_block->ictl & (ICTL_ISKE | ICTL_SSKE | ICTL_RRBE)))
+                return;
+
+        s390_enable_skey();
+        trace_kvm_s390_skey_related_inst(vcpu);
+        vcpu->arch.sie_block->ictl &= ~(ICTL_ISKE | ICTL_SSKE | ICTL_RRBE);
+}
+
+
 static int handle_skey(struct kvm_vcpu *vcpu)
 {
+        __skey_check_enable(vcpu);
+
         vcpu->stat.instruction_storage_key++;
 
         if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
@@ -618,6 +631,7 @@ static int handle_pfmf(struct kvm_vcpu *vcpu)
                 }
 
                 if (vcpu->run->s.regs.gprs[reg1] & PFMF_SK) {
+                        __skey_check_enable(vcpu);
                         if (set_guest_storage_key(current->mm, useraddr,
                                         vcpu->run->s.regs.gprs[reg1] & PFMF_KEY,
                                         vcpu->run->s.regs.gprs[reg1] & PFMF_NQ))
diff --git a/arch/s390/kvm/trace.h b/arch/s390/kvm/trace.h
index e8e7213d4cc5..a4bf7d78a0db 100644
--- a/arch/s390/kvm/trace.h
+++ b/arch/s390/kvm/trace.h
@@ -30,6 +30,20 @@
         TP_printk("%02d[%016lx-%016lx]: " p_str, __entry->id,           \
                   __entry->pswmask, __entry->pswaddr, p_args)
 
+TRACE_EVENT(kvm_s390_skey_related_inst,
+            TP_PROTO(VCPU_PROTO_COMMON),
+            TP_ARGS(VCPU_ARGS_COMMON),
+
+            TP_STRUCT__entry(
+                    VCPU_FIELD_COMMON
+                    ),
+
+            TP_fast_assign(
+                    VCPU_ASSIGN_COMMON
+                    ),
+            VCPU_TP_PRINTK("%s", "first instruction related to skeys on vcpu")
+        );
+
 TRACE_EVENT(kvm_s390_major_guest_pfault,
             TP_PROTO(VCPU_PROTO_COMMON),
             TP_ARGS(VCPU_ARGS_COMMON),