From c3235e2dd6956448a562d6b1112205eeebc8ab43 Mon Sep 17 00:00:00 2001 From: Nico Boehr Date: Mon, 9 Oct 2023 11:32:52 +0200 Subject: KVM: s390: add stat counter for shadow gmap events The shadow gmap tracks memory of nested guests (guest-3). In certain scenarios, the shadow gmap needs to be rebuilt, which is a costly operation since it involves a SIE exit into guest-1 for every entry in the respective shadow level. Add kvm stat counters when new shadow structures are created at various levels. Also add a counter gmap_shadow_create when a completely fresh shadow gmap is created as well as a counter gmap_shadow_reuse when an existing gmap is being reused. Note that when several levels are shadowed at once, counters on all affected levels will be increased. Also note that not all page table levels need to be present and a ASCE can directly point to e.g. a segment table. In this case, a new segment table will always be equivalent to a new shadow gmap and hence will be counted as gmap_shadow_create and not as gmap_shadow_segment. Signed-off-by: Nico Boehr Reviewed-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Reviewed-by: Janosch Frank Signed-off-by: Janosch Frank Link: https://lore.kernel.org/r/20231009093304.2555344-2-nrb@linux.ibm.com Message-Id: <20231009093304.2555344-2-nrb@linux.ibm.com> --- arch/s390/include/asm/kvm_host.h | 7 +++++++ arch/s390/kvm/gaccess.c | 7 +++++++ arch/s390/kvm/kvm-s390.c | 9 ++++++++- arch/s390/kvm/vsie.c | 5 ++++- 4 files changed, 26 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h index 427f9528a7b6..67a298b6cf6e 100644 --- a/arch/s390/include/asm/kvm_host.h +++ b/arch/s390/include/asm/kvm_host.h @@ -777,6 +777,13 @@ struct kvm_vm_stat { u64 inject_service_signal; u64 inject_virtio; u64 aen_forward; + u64 gmap_shadow_create; + u64 gmap_shadow_reuse; + u64 gmap_shadow_r1_entry; + u64 gmap_shadow_r2_entry; + u64 gmap_shadow_r3_entry; + u64 gmap_shadow_sg_entry; + u64 gmap_shadow_pg_entry; }; struct kvm_arch_memory_slot { diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c index 6d6bc19b37dc..ff8349d17b33 100644 --- a/arch/s390/kvm/gaccess.c +++ b/arch/s390/kvm/gaccess.c @@ -1382,6 +1382,7 @@ static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr, unsigned long *pgt, int *dat_protection, int *fake) { + struct kvm *kvm; struct gmap *parent; union asce asce; union vaddress vaddr; @@ -1390,6 +1391,7 @@ static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr, *fake = 0; *dat_protection = 0; + kvm = sg->private; parent = sg->parent; vaddr.addr = saddr; asce.val = sg->orig_asce; @@ -1450,6 +1452,7 @@ shadow_r2t: rc = gmap_shadow_r2t(sg, saddr, rfte.val, *fake); if (rc) return rc; + kvm->stat.gmap_shadow_r1_entry++; } fallthrough; case ASCE_TYPE_REGION2: { @@ -1478,6 +1481,7 @@ shadow_r3t: rc = gmap_shadow_r3t(sg, saddr, rste.val, *fake); if (rc) return rc; + kvm->stat.gmap_shadow_r2_entry++; } fallthrough; case ASCE_TYPE_REGION3: { @@ -1515,6 +1519,7 @@ shadow_sgt: rc = gmap_shadow_sgt(sg, saddr, rtte.val, *fake); if (rc) return rc; + kvm->stat.gmap_shadow_r3_entry++; } fallthrough; case ASCE_TYPE_SEGMENT: { @@ -1548,6 +1553,7 @@ shadow_pgt: rc = gmap_shadow_pgt(sg, saddr, ste.val, *fake); if (rc) return rc; + kvm->stat.gmap_shadow_sg_entry++; } } /* Return the parent address of the page table */ @@ -1618,6 +1624,7 @@ shadow_page: pte.p |= dat_protection; if (!rc) rc = gmap_shadow_page(sg, saddr, __pte(pte.val)); + vcpu->kvm->stat.gmap_shadow_pg_entry++; ipte_unlock(vcpu->kvm); mmap_read_unlock(sg->mm); return rc; diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index b3f17e014cab..b42493110d76 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -66,7 +66,14 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = { STATS_DESC_COUNTER(VM, inject_pfault_done), STATS_DESC_COUNTER(VM, inject_service_signal), STATS_DESC_COUNTER(VM, inject_virtio), - STATS_DESC_COUNTER(VM, aen_forward) + STATS_DESC_COUNTER(VM, aen_forward), + STATS_DESC_COUNTER(VM, gmap_shadow_reuse), + STATS_DESC_COUNTER(VM, gmap_shadow_create), + STATS_DESC_COUNTER(VM, gmap_shadow_r1_entry), + STATS_DESC_COUNTER(VM, gmap_shadow_r2_entry), + STATS_DESC_COUNTER(VM, gmap_shadow_r3_entry), + STATS_DESC_COUNTER(VM, gmap_shadow_sg_entry), + STATS_DESC_COUNTER(VM, gmap_shadow_pg_entry), }; const struct kvm_stats_header kvm_vm_stats_header = { diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c index 61499293c2ac..02dcbe82a8e5 100644 --- a/arch/s390/kvm/vsie.c +++ b/arch/s390/kvm/vsie.c @@ -1214,8 +1214,10 @@ static int acquire_gmap_shadow(struct kvm_vcpu *vcpu, * we're holding has been unshadowed. If the gmap is still valid, * we can safely reuse it. */ - if (vsie_page->gmap && gmap_shadow_valid(vsie_page->gmap, asce, edat)) + if (vsie_page->gmap && gmap_shadow_valid(vsie_page->gmap, asce, edat)) { + vcpu->kvm->stat.gmap_shadow_reuse++; return 0; + } /* release the old shadow - if any, and mark the prefix as unmapped */ release_gmap_shadow(vsie_page); @@ -1223,6 +1225,7 @@ static int acquire_gmap_shadow(struct kvm_vcpu *vcpu, if (IS_ERR(gmap)) return PTR_ERR(gmap); gmap->private = vcpu->kvm; + vcpu->kvm->stat.gmap_shadow_create++; WRITE_ONCE(vsie_page->gmap, gmap); return 0; } -- cgit From 70fea30195168fd84e7076720c984f0ac1af5b09 Mon Sep 17 00:00:00 2001 From: Nico Boehr Date: Mon, 9 Oct 2023 11:32:53 +0200 Subject: KVM: s390: add tracepoint in gmap notifier The gmap notifier is called for changes in table entries with the notifier bit set. To diagnose performance issues, it can be useful to see what causes certain changes in the gmap. Hence, add a tracepoint in the gmap notifier. Signed-off-by: Nico Boehr Acked-by: David Hildenbrand Reviewed-by: Claudio Imbrenda Acked-by: Janosch Frank Signed-off-by: Janosch Frank Link: https://lore.kernel.org/r/20231009093304.2555344-3-nrb@linux.ibm.com Message-Id: <20231009093304.2555344-3-nrb@linux.ibm.com> --- arch/s390/kvm/kvm-s390.c | 2 ++ arch/s390/kvm/trace-s390.h | 23 +++++++++++++++++++++++ 2 files changed, 25 insertions(+) (limited to 'arch') diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index b42493110d76..11676b81e6bf 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -4060,6 +4060,8 @@ static void kvm_gmap_notifier(struct gmap *gmap, unsigned long start, unsigned long prefix; unsigned long i; + trace_kvm_s390_gmap_notifier(start, end, gmap_is_shadow(gmap)); + if (gmap_is_shadow(gmap)) return; if (start >= 1UL << 31) diff --git a/arch/s390/kvm/trace-s390.h b/arch/s390/kvm/trace-s390.h index 6f0209d45164..9ac92dbf680d 100644 --- a/arch/s390/kvm/trace-s390.h +++ b/arch/s390/kvm/trace-s390.h @@ -333,6 +333,29 @@ TRACE_EVENT(kvm_s390_airq_suppressed, __entry->id, __entry->isc) ); +/* + * Trace point for gmap notifier calls. + */ +TRACE_EVENT(kvm_s390_gmap_notifier, + TP_PROTO(unsigned long start, unsigned long end, unsigned int shadow), + TP_ARGS(start, end, shadow), + + TP_STRUCT__entry( + __field(unsigned long, start) + __field(unsigned long, end) + __field(unsigned int, shadow) + ), + + TP_fast_assign( + __entry->start = start; + __entry->end = end; + __entry->shadow = shadow; + ), + + TP_printk("gmap notified (start:0x%lx end:0x%lx shadow:%d)", + __entry->start, __entry->end, __entry->shadow) + ); + #endif /* _TRACE_KVMS390_H */ -- cgit