KVM: s390: extend kvm_s390_shadow_fault to return entry pointer

Extend kvm_s390_shadow_fault to return the pointer to the valid leaf
DAT table entry, or to the invalid entry.

Also return some flags in the lower bits of the address:
PEI_DAT_PROT: indicates that DAT protection applies because of the
              protection bit in the segment (or, if EDAT, region) tables.
PEI_NOT_PTE: indicates that the address of the DAT table entry returned
             does not refer to a PTE, but to a segment or region table.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: stable@vger.kernel.org
Reviewed-by: Janosch Frank <frankja@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Link: https://lore.kernel.org/r/20210302174443.514363-3-imbrenda@linux.ibm.com
[borntraeger@de.ibm.com: fold in a fix from Claudio]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index 6d6b570..b9f85b2 100644 (file)
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -976,7 +976,9 @@ int kvm_s390_check_low_addr_prot_real(struct kvm_vcpu *vcpu, unsigned long gra)
  * kvm_s390_shadow_tables - walk the guest page table and create shadow tables
  * @sg: pointer to the shadow guest address space structure
  * @saddr: faulting address in the shadow gmap
- * @pgt: pointer to the page table address result
+ * @pgt: pointer to the beginning of the page table for the given address if
+ *      successful (return value 0), or to the first invalid DAT entry in
+ *      case of exceptions (return value > 0)
  * @fake: pgt references contiguous guest memory block, not a pgtable
  */
 static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr,
@@ -1034,6 +1036,7 @@ static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr,
                        rfte.val = ptr;
                        goto shadow_r2t;
                }
+               *pgt = ptr + vaddr.rfx * 8;
                rc = gmap_read_table(parent, ptr + vaddr.rfx * 8, &rfte.val);
                if (rc)
                        return rc;
@@ -1060,6 +1063,7 @@ shadow_r2t:
                        rste.val = ptr;
                        goto shadow_r3t;
                }
+               *pgt = ptr + vaddr.rsx * 8;
                rc = gmap_read_table(parent, ptr + vaddr.rsx * 8, &rste.val);
                if (rc)
                        return rc;
@@ -1087,6 +1091,7 @@ shadow_r3t:
                        rtte.val = ptr;
                        goto shadow_sgt;
                }
+               *pgt = ptr + vaddr.rtx * 8;
                rc = gmap_read_table(parent, ptr + vaddr.rtx * 8, &rtte.val);
                if (rc)
                        return rc;
@@ -1123,6 +1128,7 @@ shadow_sgt:
                        ste.val = ptr;
                        goto shadow_pgt;
                }
+               *pgt = ptr + vaddr.sx * 8;
                rc = gmap_read_table(parent, ptr + vaddr.sx * 8, &ste.val);
                if (rc)
                        return rc;
@@ -1157,6 +1163,8 @@ shadow_pgt:
  * @vcpu: virtual cpu
  * @sg: pointer to the shadow guest address space structure
  * @saddr: faulting address in the shadow gmap
+ * @datptr: will contain the address of the faulting DAT table entry, or of
+ *         the valid leaf, plus some flags
  *
  * Returns: - 0 if the shadow fault was successfully resolved
  *         - > 0 (pgm exception code) on exceptions while faulting
@@ -1165,11 +1173,11 @@ shadow_pgt:
  *         - -ENOMEM if out of memory
  */
 int kvm_s390_shadow_fault(struct kvm_vcpu *vcpu, struct gmap *sg,
-                         unsigned long saddr)
+                         unsigned long saddr, unsigned long *datptr)
 {
        union vaddress vaddr;
        union page_table_entry pte;
-       unsigned long pgt;
+       unsigned long pgt = 0;
        int dat_protection, fake;
        int rc;
 
@@ -1191,8 +1199,20 @@ int kvm_s390_shadow_fault(struct kvm_vcpu *vcpu, struct gmap *sg,
                pte.val = pgt + vaddr.px * PAGE_SIZE;
                goto shadow_page;
        }
-       if (!rc)
-               rc = gmap_read_table(sg->parent, pgt + vaddr.px * 8, &pte.val);
+
+       switch (rc) {
+       case PGM_SEGMENT_TRANSLATION:
+       case PGM_REGION_THIRD_TRANS:
+       case PGM_REGION_SECOND_TRANS:
+       case PGM_REGION_FIRST_TRANS:
+               pgt |= PEI_NOT_PTE;
+               break;
+       case 0:
+               pgt += vaddr.px * 8;
+               rc = gmap_read_table(sg->parent, pgt, &pte.val);
+       }
+       if (datptr)
+               *datptr = pgt | dat_protection * PEI_DAT_PROT;
        if (!rc && pte.i)
                rc = PGM_PAGE_TRANSLATION;
        if (!rc && pte.z)

diff --git a/arch/s390/kvm/gaccess.h b/arch/s390/kvm/gaccess.h
index 2d8631a..daba10f 100644 (file)
--- a/arch/s390/kvm/gaccess.h
+++ b/arch/s390/kvm/gaccess.h
@@ -376,7 +376,11 @@ void ipte_unlock(struct kvm_vcpu *vcpu);
 int ipte_lock_held(struct kvm_vcpu *vcpu);
 int kvm_s390_check_low_addr_prot_real(struct kvm_vcpu *vcpu, unsigned long gra);
 
+/* MVPG PEI indication bits */
+#define PEI_DAT_PROT 2
+#define PEI_NOT_PTE 4
+
 int kvm_s390_shadow_fault(struct kvm_vcpu *vcpu, struct gmap *shadow,
-                         unsigned long saddr);
+                         unsigned long saddr, unsigned long *datptr);
 
 #endif /* __KVM_S390_GACCESS_H */

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index bd803e0..78b6043 100644 (file)
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -620,10 +620,10 @@ static int map_prefix(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
        /* with mso/msl, the prefix lies at offset *mso* */
        prefix += scb_s->mso;
 
-       rc = kvm_s390_shadow_fault(vcpu, vsie_page->gmap, prefix);
+       rc = kvm_s390_shadow_fault(vcpu, vsie_page->gmap, prefix, NULL);
        if (!rc && (scb_s->ecb & ECB_TE))
                rc = kvm_s390_shadow_fault(vcpu, vsie_page->gmap,
-                                          prefix + PAGE_SIZE);
+                                          prefix + PAGE_SIZE, NULL);
        /*
         * We don't have to mprotect, we will be called for all unshadows.
         * SIE will detect if protection applies and trigger a validity.
@@ -914,7 +914,7 @@ static int handle_fault(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
                                    current->thread.gmap_addr, 1);
 
        rc = kvm_s390_shadow_fault(vcpu, vsie_page->gmap,
-                                  current->thread.gmap_addr);
+                                  current->thread.gmap_addr, NULL);
        if (rc > 0) {
                rc = inject_fault(vcpu, rc,
                                  current->thread.gmap_addr,
@@ -936,7 +936,7 @@ static void handle_last_fault(struct kvm_vcpu *vcpu,
 {
        if (vsie_page->fault_addr)
                kvm_s390_shadow_fault(vcpu, vsie_page->gmap,
-                                     vsie_page->fault_addr);
+                                     vsie_page->fault_addr, NULL);
        vsie_page->fault_addr = 0;
 }