Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
KVM: s390: Correctly handle guest mappings without struct page
Introduce a new special softbit for large pages, like already presend
for normal pages, and use it to mark guest mappings that do not have
struct pages.
Whenever a leaf DAT entry becomes dirty, check the special softbit and
only call SetPageDirty() if there is an actual struct page.
Move the logic to mark pages dirty inside _gmap_ptep_xchg() and
_gmap_crstep_xchg_atomic(), to avoid needlessly duplicating the code.
Fixes: 5a74e3d93417 ("KVM: s390: KVM-specific bitfields and helper functions")
Fixes: a2c17f9270cc ("KVM: s390: New gmap code")
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
+14
-13
+6
-6
arch/s390/kvm/dat.h
+6
-6
arch/s390/kvm/dat.h
···
160
160
unsigned long :44; /* HW */
161
161
unsigned long : 3; /* Unused */
162
162
unsigned long : 1; /* HW */
163
+
unsigned long s : 1; /* Special */
163
164
unsigned long w : 1; /* Writable soft-bit */
164
165
unsigned long r : 1; /* Readable soft-bit */
165
166
unsigned long d : 1; /* Dirty */
166
167
unsigned long y : 1; /* Young */
167
-
unsigned long prefix_notif : 1; /* Guest prefix invalidation notification */
168
168
unsigned long : 3; /* HW */
169
+
unsigned long prefix_notif : 1; /* Guest prefix invalidation notification */
169
170
unsigned long vsie_notif : 1; /* Referenced in a shadow table */
170
-
unsigned long : 1; /* Unused */
171
171
unsigned long : 4; /* HW */
172
172
unsigned long sd : 1; /* Soft-Dirty */
173
173
unsigned long pr : 1; /* Present */
···
183
183
unsigned long :33; /* HW */
184
184
unsigned long :14; /* Unused */
185
185
unsigned long : 1; /* HW */
186
+
unsigned long s : 1; /* Special */
186
187
unsigned long w : 1; /* Writable soft-bit */
187
188
unsigned long r : 1; /* Readable soft-bit */
188
189
unsigned long d : 1; /* Dirty */
189
190
unsigned long y : 1; /* Young */
190
-
unsigned long prefix_notif : 1; /* Guest prefix invalidation notification */
191
191
unsigned long : 3; /* HW */
192
+
unsigned long prefix_notif : 1; /* Guest prefix invalidation notification */
192
193
unsigned long vsie_notif : 1; /* Referenced in a shadow table */
193
-
unsigned long : 1; /* Unused */
194
194
unsigned long : 4; /* HW */
195
195
unsigned long sd : 1; /* Soft-Dirty */
196
196
unsigned long pr : 1; /* Present */
···
254
254
struct {
255
255
unsigned long :47;
256
256
unsigned long : 1; /* HW (should be 0) */
257
+
unsigned long s : 1; /* Special */
257
258
unsigned long w : 1; /* Writable */
258
259
unsigned long r : 1; /* Readable */
259
260
unsigned long d : 1; /* Dirty */
260
261
unsigned long y : 1; /* Young */
261
-
unsigned long prefix_notif : 1; /* Guest prefix invalidation notification */
262
262
unsigned long : 3; /* HW */
263
+
unsigned long prefix_notif : 1; /* Guest prefix invalidation notification */
263
264
unsigned long vsie_notif : 1; /* Referenced in a shadow table */
264
-
unsigned long : 1;
265
265
unsigned long : 4; /* HW */
266
266
unsigned long sd : 1; /* Soft-Dirty */
267
267
unsigned long pr : 1; /* Present */
+4
-7
arch/s390/kvm/gmap.c
+4
-7
arch/s390/kvm/gmap.c
···
519
519
_dat_walk_gfn_range(start, end, gmap->asce, &walk_ops, 0, gmap);
520
520
}
521
521
522
-
static int gmap_handle_minor_crste_fault(union asce asce, struct guest_fault *f)
522
+
static int gmap_handle_minor_crste_fault(struct gmap *gmap, struct guest_fault *f)
523
523
{
524
524
union crste newcrste, oldcrste = READ_ONCE(*f->crstep);
525
525
···
544
544
newcrste.s.fc1.d = 1;
545
545
newcrste.s.fc1.sd = 1;
546
546
}
547
-
if (!oldcrste.s.fc1.d && newcrste.s.fc1.d)
548
-
SetPageDirty(phys_to_page(crste_origin_large(newcrste)));
549
547
/* In case of races, let the slow path deal with it. */
550
-
return !dat_crstep_xchg_atomic(f->crstep, oldcrste, newcrste, f->gfn, asce);
548
+
return !gmap_crstep_xchg_atomic(gmap, f->crstep, oldcrste, newcrste, f->gfn);
551
549
}
552
550
/* Trying to write on a read-only page, let the slow path deal with it. */
553
551
return 1;
···
574
576
newpte.s.d = 1;
575
577
newpte.s.sd = 1;
576
578
}
577
-
if (!oldpte.s.d && newpte.s.d)
578
-
SetPageDirty(pfn_to_page(newpte.h.pfra));
579
579
*pgste = gmap_ptep_xchg(gmap, f->ptep, newpte, *pgste, f->gfn);
580
580
581
581
return 0;
···
610
614
fault->callback(fault);
611
615
pgste_set_unlock(fault->ptep, pgste);
612
616
} else {
613
-
rc = gmap_handle_minor_crste_fault(gmap->asce, fault);
617
+
rc = gmap_handle_minor_crste_fault(gmap, fault);
614
618
if (!rc && fault->callback)
615
619
fault->callback(fault);
616
620
}
···
665
669
oldval = READ_ONCE(*f->crstep);
666
670
newval = _crste_fc1(f->pfn, oldval.h.tt, f->writable,
667
671
f->write_attempt | oldval.s.fc1.d);
672
+
newval.s.fc1.s = !f->page;
668
673
newval.s.fc1.sd = oldval.s.fc1.sd;
669
674
if (oldval.val != _CRSTE_EMPTY(oldval.h.tt).val &&
670
675
crste_origin_large(oldval) != crste_origin_large(newval))
+4
arch/s390/kvm/gmap.h
+4
arch/s390/kvm/gmap.h
···
185
185
else
186
186
_gmap_handle_vsie_unshadow_event(gmap, gfn);
187
187
}
188
+
if (!ptep->s.d && newpte.s.d && !newpte.s.s)
189
+
SetPageDirty(pfn_to_page(newpte.h.pfra));
188
190
return __dat_ptep_xchg(ptep, pgste, newpte, gfn, gmap->asce, uses_skeys(gmap));
189
191
}
190
192
···
222
220
else
223
221
_gmap_handle_vsie_unshadow_event(gmap, gfn);
224
222
}
223
+
if (!oldcrste.s.fc1.d && newcrste.s.fc1.d && !newcrste.s.fc1.s)
224
+
SetPageDirty(phys_to_page(crste_origin_large(newcrste)));
225
225
return dat_crstep_xchg_atomic(crstep, oldcrste, newcrste, gfn, gmap->asce);
226
226
}
227
227