[S390] kvm: handle tprot intercepts

When running a kvm guest we can get intercepts for tprot, if the host
page table is read-only or not populated. This patch implements the
most common case (linux memory detection).
This also allows host copy on write for guest memory on newer systems.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

5 files changed, 53 insertions, 0 deletions

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index cef7dbf69dfc..e9bcdca32a32 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -138,6 +138,7 @@ struct kvm_vcpu_stat {
         u32 instruction_chsc;
         u32 instruction_stsi;
         u32 instruction_stfl;
+        u32 instruction_tprot;
         u32 instruction_sigp_sense;
         u32 instruction_sigp_emergency;
         u32 instruction_sigp_stop;
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index f7b6df45d8be..b5312050b224 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -105,6 +105,7 @@ static intercept_handler_t instruction_handlers[256] = {
         [0xae] = kvm_s390_handle_sigp,
         [0xb2] = kvm_s390_handle_b2,
         [0xb7] = handle_lctl,
+        [0xe5] = kvm_s390_handle_e5,
         [0xeb] = handle_lctlg,
 };
 
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 67345ae7ce8d..123ebea72282 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -62,6 +62,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
         { "instruction_chsc", VCPU_STAT(instruction_chsc) },
         { "instruction_stsi", VCPU_STAT(instruction_stsi) },
         { "instruction_stfl", VCPU_STAT(instruction_stfl) },
+        { "instruction_tprot", VCPU_STAT(instruction_tprot) },
         { "instruction_sigp_sense", VCPU_STAT(instruction_sigp_sense) },
         { "instruction_sigp_emergency", VCPU_STAT(instruction_sigp_emergency) },
         { "instruction_sigp_stop", VCPU_STAT(instruction_sigp_stop) },
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index a7b7586626db..65e2201a555b 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -87,6 +87,7 @@ static inline void kvm_s390_vcpu_set_mem(struct kvm_vcpu *vcpu)
 
 /* implemented in priv.c */
 int kvm_s390_handle_b2(struct kvm_vcpu *vcpu);
+int kvm_s390_handle_e5(struct kvm_vcpu *vcpu);
 
 /* implemented in sigp.c */
 int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu);
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 73c47bd95db3..391626361084 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -326,3 +326,52 @@ int kvm_s390_handle_b2(struct kvm_vcpu *vcpu)
         }
         return -EOPNOTSUPP;
 }
+
+static int handle_tprot(struct kvm_vcpu *vcpu)
+{
+        int base1 = (vcpu->arch.sie_block->ipb & 0xf0000000) >> 28;
+        int disp1 = (vcpu->arch.sie_block->ipb & 0x0fff0000) >> 16;
+        int base2 = (vcpu->arch.sie_block->ipb & 0xf000) >> 12;
+        int disp2 = vcpu->arch.sie_block->ipb & 0x0fff;
+        u64 address1 = disp1 + base1 ? vcpu->arch.guest_gprs[base1] : 0;
+        u64 address2 = disp2 + base2 ? vcpu->arch.guest_gprs[base2] : 0;
+        struct vm_area_struct *vma;
+
+        vcpu->stat.instruction_tprot++;
+
+        /* we only handle the Linux memory detection case:
+         * access key == 0
+         * guest DAT == off
+         * everything else goes to userspace. */
+        if (address2 & 0xf0)
+                return -EOPNOTSUPP;
+        if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_DAT)
+                return -EOPNOTSUPP;
+
+
+        down_read(&current->mm->mmap_sem);
+        vma = find_vma(current->mm,
+                        (unsigned long) __guestaddr_to_user(vcpu, address1));
+        if (!vma) {
+                up_read(&current->mm->mmap_sem);
+                return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
+        }
+
+        vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
+        if (!(vma->vm_flags & VM_WRITE) && (vma->vm_flags & VM_READ))
+                vcpu->arch.sie_block->gpsw.mask |= (1ul << 44);
+        if (!(vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_READ))
+                vcpu->arch.sie_block->gpsw.mask |= (2ul << 44);
+
+        up_read(&current->mm->mmap_sem);
+        return 0;
+}
+
+int kvm_s390_handle_e5(struct kvm_vcpu *vcpu)
+{
+        /* For e5xx... instructions we only handle TPROT */
+        if ((vcpu->arch.sie_block->ipa & 0x00ff) == 0x01)
+                return handle_tprot(vcpu);
+        return -EOPNOTSUPP;
+}
+