[PATCH v1 0/3] KVM: s390: A few misc gmap fixes.

[PATCH v1 0/3] KVM: s390: A few misc gmap fixes.

[Claudio Imbrenda]

A few more minor gmap fixes.

Claudio Imbrenda (3):
  KVM: s390: Silence potential warnings in _gmap_crstep_xchg_atomic()
  KVM: s390: Fix unlikely race in try_get_locked_pte()
  KVM: s390: vsie: Use mmu cache to allocate rmap

 arch/s390/kvm/gaccess.c     | 16 ++++++++--------
 arch/s390/kvm/gmap.c        |  7 ++++---
 arch/s390/kvm/gmap.h        |  9 +++++++--
 arch/s390/mm/gmap_helpers.c |  6 +++---
 4 files changed, 22 insertions(+), 16 deletions(-)

-- 
2.54.0

[PATCH v1 1/3] KVM: s390: Silence potential warnings in _gmap_crstep_xchg_atomic()

[Claudio Imbrenda]

While dat_crstep_xchg_atomic() is marked as __must_check, in this
particular case the return value should be ignored.

Add an explicit (void) cast to silence potential compiler warnings, and
a comment to explain why it is ok to do so.

Fixes: d1adc098ce08 ("KVM: s390: Fix _gmap_crstep_xchg_atomic()")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
CC: stable@vger.kernel.org # 7.1
---
 arch/s390/kvm/gmap.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kvm/gmap.h b/arch/s390/kvm/gmap.h
index 5374f21aaf8d..4e6979783e16 100644
--- a/arch/s390/kvm/gmap.h
+++ b/arch/s390/kvm/gmap.h
@@ -279,7 +279,11 @@ static inline bool __must_check _gmap_crstep_xchg_atomic(struct gmap *gmap, unio
 			gmap_handle_vsie_unshadow_event(gmap, gfn);
 		else
 			_gmap_handle_vsie_unshadow_event(gmap, gfn);
-		dat_crstep_xchg_atomic(crstep, oldcrste, newcrste, gfn, gmap->asce);
+		/*
+		 * Ignore the result, it's just a best effort clearing of the
+		 * vsie_notif bit. The caller will have to try again regardless.
+		 */
+		(void)dat_crstep_xchg_atomic(crstep, oldcrste, newcrste, gfn, gmap->asce);
 		return false;
 	}
 	if (!oldcrste.s.fc1.d && newcrste.s.fc1.d && !newcrste.s.fc1.s)
-- 
2.54.0

[PATCH v1 2/3] KVM: s390: Fix unlikely race in try_get_locked_pte()

[Claudio Imbrenda]

Fix an unlikely race in try_get_locked_pte(), which could have happened
if puds or pmds get unmapped between the p?dp_get() and p?d_offset()
functions.

Fixes: 89fa757931dc ("KVM: s390: Avoid potentially sleeping while atomic when zapping pages")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
CC: stable@vger.kernel.org # 7.1
---
 arch/s390/mm/gmap_helpers.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/s390/mm/gmap_helpers.c b/arch/s390/mm/gmap_helpers.c
index 1cfe4724fbe2..ee3f37af8aee 100644
--- a/arch/s390/mm/gmap_helpers.c
+++ b/arch/s390/mm/gmap_helpers.c
@@ -51,15 +51,15 @@ pte_t *try_get_locked_pte(struct mm_struct *mm, unsigned long vmaddr, spinlock_t
 	pgd = pgdp_get(pgdp);
 	if (pgd_none(pgd) || !pgd_present(pgd))
 		return NULL;
-	p4dp = p4d_offset(pgdp, vmaddr);
+	p4dp = p4d_offset_lockless(pgdp, pgd, vmaddr);
 	p4d = p4dp_get(p4dp);
 	if (p4d_none(p4d) || !p4d_present(p4d))
 		return NULL;
-	pudp = pud_offset(p4dp, vmaddr);
+	pudp = pud_offset_lockless(p4dp, p4d, vmaddr);
 	pud = pudp_get(pudp);
 	if (pud_none(pud) || pud_leaf(pud) || !pud_present(pud))
 		return NULL;
-	pmdp = pmd_offset(pudp, vmaddr);
+	pmdp = pmd_offset_lockless(pudp, pud, vmaddr);
 	pmd = pmdp_get_lockless(pmdp);
 	if (pmd_none(pmd) || pmd_leaf(pmd) || !pmd_present(pmd))
 		return NULL;
-- 
2.54.0

[PATCH v1 3/3] KVM: s390: vsie: Use mmu cache to allocate rmap

[Claudio Imbrenda]

Use kvm_s390_mmu_cache_alloc_rmap() to allocate the rmap in
gmap_insert_rmap(), instead of a normal kzalloc_obj() with GFP_ATOMIC.

This guarantees forward progress.

Fixes: a2c17f9270cc ("KVM: s390: New gmap code")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
CC: stable@vger.kernel.org # 7.1
---
 arch/s390/kvm/gaccess.c | 16 ++++++++--------
 arch/s390/kvm/gmap.c    |  7 ++++---
 arch/s390/kvm/gmap.h    |  3 ++-
 3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index 20e28b183c1a..022ea7736521 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -1419,8 +1419,8 @@ static int walk_guest_tables(struct gmap *sg, unsigned long saddr, struct pgtwal
 	return kvm_s390_get_guest_page(kvm, entries + LEVEL_MEM, table.pte.pfra, wr);
 }
 
-static int _do_shadow_pte(struct gmap *sg, gpa_t raddr, union pte *ptep_h, union pte *ptep,
-			  struct guest_fault *f, bool p)
+static int _do_shadow_pte(struct kvm_s390_mmu_cache *mc, struct gmap *sg, gpa_t raddr,
+			  union pte *ptep_h, union pte *ptep, struct guest_fault *f, bool p)
 {
 	union pgste pgste;
 	union pte newpte;
@@ -1430,7 +1430,7 @@ static int _do_shadow_pte(struct gmap *sg, gpa_t raddr, union pte *ptep_h, union
 	lockdep_assert_held(&sg->parent->children_lock);
 
 	scoped_guard(spinlock, &sg->host_to_rmap_lock)
-		rc = gmap_insert_rmap(sg, f->gfn, gpa_to_gfn(raddr), TABLE_TYPE_PAGE_TABLE);
+		rc = gmap_insert_rmap(mc, sg, f->gfn, gpa_to_gfn(raddr), TABLE_TYPE_PAGE_TABLE);
 	if (rc)
 		return rc;
 
@@ -1462,8 +1462,8 @@ static int _do_shadow_pte(struct gmap *sg, gpa_t raddr, union pte *ptep_h, union
 	return 0;
 }
 
-static int _do_shadow_crste(struct gmap *sg, gpa_t raddr, union crste *host, union crste *table,
-			    struct guest_fault *f, bool p)
+static int _do_shadow_crste(struct kvm_s390_mmu_cache *mc, struct gmap *sg, gpa_t raddr,
+			    union crste *host, union crste *table, struct guest_fault *f, bool p)
 {
 	union crste newcrste, oldcrste;
 	unsigned long mask;
@@ -1476,7 +1476,7 @@ static int _do_shadow_crste(struct gmap *sg, gpa_t raddr, union crste *host, uni
 	mask = is_pmd(*table) ? _SEGMENT_FR_MASK : _REGION3_FR_MASK;
 	r_gfn = gpa_to_gfn(raddr) & mask;
 	scoped_guard(spinlock, &sg->host_to_rmap_lock)
-		rc = gmap_insert_rmap(sg, f->gfn & mask, r_gfn, host->h.tt);
+		rc = gmap_insert_rmap(mc, sg, f->gfn & mask, r_gfn, host->h.tt);
 	if (rc)
 		return rc;
 
@@ -1578,8 +1578,8 @@ static int _gaccess_do_shadow(struct kvm_s390_mmu_cache *mc, struct gmap *sg,
 	if (KVM_BUG_ON(l > TABLE_TYPE_REGION3, sg->kvm))
 		return -EFAULT;
 	if (l == TABLE_TYPE_PAGE_TABLE)
-		return _do_shadow_pte(sg, saddr, ptep_h, ptep, entries + LEVEL_MEM, w->p);
-	return _do_shadow_crste(sg, saddr, host, table, entries + LEVEL_MEM, w->p);
+		return _do_shadow_pte(mc, sg, saddr, ptep_h, ptep, entries + LEVEL_MEM, w->p);
+	return _do_shadow_crste(mc, sg, saddr, host, table, entries + LEVEL_MEM, w->p);
 }
 
 static inline int _gaccess_shadow_fault(struct kvm_vcpu *vcpu, struct gmap *sg, gpa_t saddr,
diff --git a/arch/s390/kvm/gmap.c b/arch/s390/kvm/gmap.c
index 52d55ddea8d4..1d289f8fa3b2 100644
--- a/arch/s390/kvm/gmap.c
+++ b/arch/s390/kvm/gmap.c
@@ -1000,7 +1000,8 @@ int gmap_pv_destroy_range(struct gmap *gmap, gfn_t start, gfn_t end, bool interr
 	return 0;
 }
 
-int gmap_insert_rmap(struct gmap *sg, gfn_t p_gfn, gfn_t r_gfn, int level)
+int gmap_insert_rmap(struct kvm_s390_mmu_cache *mc, struct gmap *sg, gfn_t p_gfn,
+		     gfn_t r_gfn, int level)
 {
 	struct vsie_rmap *rmap __free(kvfree) = NULL;
 	struct vsie_rmap *temp;
@@ -1010,7 +1011,7 @@ int gmap_insert_rmap(struct gmap *sg, gfn_t p_gfn, gfn_t r_gfn, int level)
 	KVM_BUG_ON(!is_shadow(sg), sg->kvm);
 	lockdep_assert_held(&sg->host_to_rmap_lock);
 
-	rmap = kzalloc_obj(*rmap, GFP_ATOMIC);
+	rmap = kvm_s390_mmu_cache_alloc_rmap(mc);
 	if (!rmap)
 		return -ENOMEM;
 
@@ -1057,7 +1058,7 @@ int gmap_protect_rmap(struct kvm_s390_mmu_cache *mc, struct gmap *sg, gfn_t p_gf
 	if (level <= TABLE_TYPE_REGION1) {
 		bitmask = -1UL << (8 + 11 * level);
 		scoped_guard(spinlock, &sg->host_to_rmap_lock)
-			rc = gmap_insert_rmap(sg, p_gfn, r_gfn & bitmask, level);
+			rc = gmap_insert_rmap(mc, sg, p_gfn, r_gfn & bitmask, level);
 	}
 	if (rc)
 		return rc;
diff --git a/arch/s390/kvm/gmap.h b/arch/s390/kvm/gmap.h
index 4e6979783e16..75df5d39bd78 100644
--- a/arch/s390/kvm/gmap.h
+++ b/arch/s390/kvm/gmap.h
@@ -100,7 +100,8 @@ int gmap_ucas_map(struct gmap *gmap, gfn_t p_gfn, gfn_t c_gfn, unsigned long cou
 void gmap_ucas_unmap(struct gmap *gmap, gfn_t c_gfn, unsigned long count);
 int gmap_enable_skeys(struct gmap *gmap);
 int gmap_pv_destroy_range(struct gmap *gmap, gfn_t start, gfn_t end, bool interruptible);
-int gmap_insert_rmap(struct gmap *sg, gfn_t p_gfn, gfn_t r_gfn, int level);
+int gmap_insert_rmap(struct kvm_s390_mmu_cache *mc, struct gmap *sg, gfn_t p_gfn,
+		     gfn_t r_gfn, int level);
 int gmap_protect_rmap(struct kvm_s390_mmu_cache *mc, struct gmap *sg, gfn_t p_gfn, gfn_t r_gfn,
 		      kvm_pfn_t pfn, int level, bool wr);
 void gmap_set_cmma_all_dirty(struct gmap *gmap);
-- 
2.54.0