Commit 19c21d2d authored by Nico Boehr's avatar Nico Boehr Committed by Ma Wupeng
Browse files

KVM: s390: add stat counter for shadow gmap events 

stable inclusion
from stable-v6.6.22
commit 99b86c9b07a31ca14e19fcb3bba93dedf7bdfff0
bugzilla: https://gitee.com/openeuler/kernel/issues/I99TJK

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=99b86c9b07a31ca14e19fcb3bba93dedf7bdfff0



--------------------------------

[ Upstream commit c3235e2dd6956448a562d6b1112205eeebc8ab43 ]

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: default avatarNico Boehr <nrb@linux.ibm.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20231009093304.2555344-2-nrb@linux.ibm.com


Message-Id: <20231009093304.2555344-2-nrb@linux.ibm.com>
Stable-dep-of: fe752331d4b3 ("KVM: s390: vsie: fix race during shadow creation")
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarZhangPeng <zhangpeng362@huawei.com>
parent 09a17c4b

arch/s390/include/asm/kvm_host.h

+7 −0
Original line number Diff line number Diff line
@@ -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 {

arch/s390/kvm/gaccess.c

+7 −0
Original line number Diff line number Diff line
@@ -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 @@ static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr, 
		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 @@ static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr, 
		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 @@ static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr, 
		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 @@ static int kvm_s390_shadow_tables(struct gmap *sg, unsigned long saddr, 
		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 @@ int kvm_s390_shadow_fault(struct kvm_vcpu *vcpu, struct gmap *sg, 
	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;

arch/s390/kvm/kvm-s390.c

+8 −1
Original line number Diff line number Diff line
@@ -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 = {

arch/s390/kvm/vsie.c

+4 −1
Original line number Diff line number Diff line
@@ -1210,8 +1210,10 @@ 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);
@@ -1219,6 +1221,7 @@ 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;

}