KVM: s390: pfmf: fix end address calculation

The current calculation is wrong if absolute != real address. Let's just
calculate the start address for 4k frames upfront. Otherwise, the
calculated end address will be wrong, resulting in wrong memory
location/storage keys getting touched.

To keep low-address protection working (using the effective address),
we have to move the check.

Reviewed-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>

1 files changed, 9 insertions, 11 deletions

diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index c6deed782c61..bfba98302ca0 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -682,8 +682,15 @@ static int handle_pfmf(struct kvm_vcpu *vcpu)
         start = vcpu->run->s.regs.gprs[reg2] & PAGE_MASK;
         start = kvm_s390_logical_to_effective(vcpu, start);
 
+        if (vcpu->run->s.regs.gprs[reg1] & PFMF_CF) {
+                if (kvm_s390_check_low_addr_prot_real(vcpu, start))
+                        return kvm_s390_inject_prog_irq(vcpu, &vcpu->arch.pgm);
+        }
+
         switch (vcpu->run->s.regs.gprs[reg1] & PFMF_FSC) {
         case 0x00000000:
+                /* only 4k frames specify a real address */
+                start = kvm_s390_real_to_abs(vcpu, start);
                 end = (start + (1UL << 12)) & ~((1UL << 12) - 1);
                 break;
         case 0x00001000:
@@ -701,20 +708,11 @@ static int handle_pfmf(struct kvm_vcpu *vcpu)
                 return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
         }
 
-        if (vcpu->run->s.regs.gprs[reg1] & PFMF_CF) {
-                if (kvm_s390_check_low_addr_prot_real(vcpu, start))
-                        return kvm_s390_inject_prog_irq(vcpu, &vcpu->arch.pgm);
-        }
-
         while (start < end) {
-                unsigned long useraddr, abs_addr;
+                unsigned long useraddr;
 
                 /* Translate guest address to host address */
-                if ((vcpu->run->s.regs.gprs[reg1] & PFMF_FSC) == 0)
-                        abs_addr = kvm_s390_real_to_abs(vcpu, start);
-                else
-                        abs_addr = start;
-                useraddr = gfn_to_hva(vcpu->kvm, gpa_to_gfn(abs_addr));
+                useraddr = gfn_to_hva(vcpu->kvm, gpa_to_gfn(start));
                 if (kvm_is_error_hva(useraddr))
                         return kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);