[PATCH v1 06/11] KVM: s390: Introduce extended topup for struct kvm_s390_mmu_cache

In most cases the mmu caches should not blow up in size unnecessarily,
since there is one for each vCPU, as it can add up to a quite big
amount of memory. In some cases, though, it is necessary to have a
particularly large mmu cache, to guarantee that specific operations can
complete without needing to refill the cache.

This patch refactors the existing kvm_s390_mmu_cache_topup() function
to allow for an extended top-up. Two wrappers are also provided, one
with the old name and old behaviour, and one that performs the extended
top-up.

Signed-off-by: Claudio Imbrenda <[email protected]>
---
 arch/s390/kvm/dat.c | 11 +++++++----
 arch/s390/kvm/dat.h | 25 +++++++++++++++++++++----
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/arch/s390/kvm/dat.c b/arch/s390/kvm/dat.c
index f4dd6f783417..47ff8af1b22f 100644
--- a/arch/s390/kvm/dat.c
+++ b/arch/s390/kvm/dat.c
@@ -28,23 +28,26 @@
 #include <asm/tlb.h>
 #include "dat.h"
 
-int kvm_s390_mmu_cache_topup(struct kvm_s390_mmu_cache *mc)
+int _kvm_s390_mmu_cache_topup(struct kvm_s390_mmu_cache *mc, bool extended)
 {
+	size_t n_crsts = extended ? KVM_S390_MMU_CACHE_N_CRSTS_MAX : KVM_S390_MMU_CACHE_N_CRSTS;
+	size_t n_pts = extended ? KVM_S390_MMU_CACHE_N_PTS_MAX : KVM_S390_MMU_CACHE_N_PTS;
+	size_t n_rmaps = extended ? KVM_S390_MMU_CACHE_N_RMAPS_MAX : KVM_S390_MMU_CACHE_N_RMAPS;
 	void *o;
 
-	for ( ; mc->n_crsts < KVM_S390_MMU_CACHE_N_CRSTS; mc->n_crsts++) {
+	for ( ; mc->n_crsts < n_crsts; mc->n_crsts++) {
 		o = (void *)__get_free_pages(GFP_KERNEL_ACCOUNT | __GFP_COMP, CRST_ALLOC_ORDER);
 		if (!o)
 			return -ENOMEM;
 		mc->crsts[mc->n_crsts] = o;
 	}
-	for ( ; mc->n_pts < KVM_S390_MMU_CACHE_N_PTS; mc->n_pts++) {
+	for ( ; mc->n_pts < n_pts; mc->n_pts++) {
 		o = (void *)__get_free_page(GFP_KERNEL_ACCOUNT);
 		if (!o)
 			return -ENOMEM;
 		mc->pts[mc->n_pts] = o;
 	}
-	for ( ; mc->n_rmaps < KVM_S390_MMU_CACHE_N_RMAPS; mc->n_rmaps++) {
+	for ( ; mc->n_rmaps < n_rmaps; mc->n_rmaps++) {
 		o = kzalloc_obj(struct vsie_rmap, GFP_KERNEL_ACCOUNT);
 		if (!o)
 			return -ENOMEM;
diff --git a/arch/s390/kvm/dat.h b/arch/s390/kvm/dat.h
index 141ee7b9f019..461302f05e50 100644
--- a/arch/s390/kvm/dat.h
+++ b/arch/s390/kvm/dat.h
@@ -479,13 +479,20 @@ struct vsie_rmap {
 
 static_assert(sizeof(struct vsie_rmap) == 2 * sizeof(long));
 
+/* Used when performing normal top-ups */
 #define KVM_S390_MMU_CACHE_N_CRSTS	6
 #define KVM_S390_MMU_CACHE_N_PTS	2
 #define KVM_S390_MMU_CACHE_N_RMAPS	16
+
+/* Used to perform special extended top-ups */
+#define KVM_S390_MMU_CACHE_N_CRSTS_MAX	32
+#define KVM_S390_MMU_CACHE_N_PTS_MAX	8
+#define KVM_S390_MMU_CACHE_N_RMAPS_MAX	16
+
 struct kvm_s390_mmu_cache {
-	void *crsts[KVM_S390_MMU_CACHE_N_CRSTS];
-	void *pts[KVM_S390_MMU_CACHE_N_PTS];
-	void *rmaps[KVM_S390_MMU_CACHE_N_RMAPS];
+	void *crsts[KVM_S390_MMU_CACHE_N_CRSTS_MAX];
+	void *pts[KVM_S390_MMU_CACHE_N_PTS_MAX];
+	void *rmaps[KVM_S390_MMU_CACHE_N_RMAPS_MAX];
 	short int n_crsts;
 	short int n_pts;
 	short int n_rmaps;
@@ -555,7 +562,17 @@ int dat_get_cmma(union asce asce, gfn_t *start, unsigned int *count, u8 *values,
 int dat_set_cmma_bits(struct kvm_s390_mmu_cache *mc, union asce asce, gfn_t gfn,
 		      unsigned long count, unsigned long mask, const uint8_t *bits);
 
-int kvm_s390_mmu_cache_topup(struct kvm_s390_mmu_cache *mc);
+int _kvm_s390_mmu_cache_topup(struct kvm_s390_mmu_cache *mc, bool extended);
+
+static inline int kvm_s390_mmu_cache_topup(struct kvm_s390_mmu_cache *mc)
+{
+	return _kvm_s390_mmu_cache_topup(mc, false);
+}
+
+static inline int kvm_s390_mmu_cache_extended_topup(struct kvm_s390_mmu_cache *mc)
+{
+	return _kvm_s390_mmu_cache_topup(mc, true);
+}
 
 #define GFP_KVM_S390_MMU_CACHE (GFP_ATOMIC | __GFP_ACCOUNT | __GFP_NOWARN)
 
-- 
2.55.0