Commit 14542a0a authored by Christoph Schlameuss's avatar Christoph Schlameuss Committed by Janosch Frank
Browse files

KVM: S390: Remove sca_lock 



Since we are no longer switching from a BSCA to a ESCA we can completely
get rid of the sca_lock. The write lock was only taken for that
conversion.

After removal of the lock some local code cleanups are possible.

Signed-off-by: default avatarChristoph Schlameuss <schlameuss@linux.ibm.com>
Suggested-by: default avatarJanosch Frank <frankja@linux.ibm.com>
[frankja@linux.ibm.com: Added suggested-by tag as discussed on list]
Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
parent e72753ed

arch/s390/include/asm/kvm_host.h

+0 −1
Original line number Diff line number Diff line
@@ -633,7 +633,6 @@ struct kvm_s390_pv { 


struct kvm_arch {

	struct esca_block *sca;

	rwlock_t sca_lock;

	debug_info_t *dbf;

	struct kvm_s390_float_interrupt float_int;

	struct kvm_device *flic;

arch/s390/kvm/gaccess.c

+2 −17
Original line number Diff line number Diff line
@@ -109,14 +109,9 @@ struct aste { 


int ipte_lock_held(struct kvm *kvm)

{

	if (sclp.has_siif) {

		int rc;

	if (sclp.has_siif)

		return kvm->arch.sca->ipte_control.kh != 0;



		read_lock(&kvm->arch.sca_lock);

		rc = kvm->arch.sca->ipte_control.kh != 0;

		read_unlock(&kvm->arch.sca_lock);

		return rc;

	}

	return kvm->arch.ipte_lock_count != 0;

}
@@ -129,19 +124,16 @@ static void ipte_lock_simple(struct kvm *kvm) 
	if (kvm->arch.ipte_lock_count > 1)

		goto out;

retry:

	read_lock(&kvm->arch.sca_lock);

	ic = &kvm->arch.sca->ipte_control;

	old = READ_ONCE(*ic);

	do {

		if (old.k) {

			read_unlock(&kvm->arch.sca_lock);

			cond_resched();

			goto retry;

		}

		new = old;

		new.k = 1;

	} while (!try_cmpxchg(&ic->val, &old.val, new.val));

	read_unlock(&kvm->arch.sca_lock);

out:

	mutex_unlock(&kvm->arch.ipte_mutex);

}
@@ -154,14 +146,12 @@ static void ipte_unlock_simple(struct kvm *kvm) 
	kvm->arch.ipte_lock_count--;

	if (kvm->arch.ipte_lock_count)

		goto out;

	read_lock(&kvm->arch.sca_lock);

	ic = &kvm->arch.sca->ipte_control;

	old = READ_ONCE(*ic);

	do {

		new = old;

		new.k = 0;

	} while (!try_cmpxchg(&ic->val, &old.val, new.val));

	read_unlock(&kvm->arch.sca_lock);

	wake_up(&kvm->arch.ipte_wq);

out:

	mutex_unlock(&kvm->arch.ipte_mutex);
@@ -172,12 +162,10 @@ static void ipte_lock_siif(struct kvm *kvm) 
	union ipte_control old, new, *ic;



retry:

	read_lock(&kvm->arch.sca_lock);

	ic = &kvm->arch.sca->ipte_control;

	old = READ_ONCE(*ic);

	do {

		if (old.kg) {

			read_unlock(&kvm->arch.sca_lock);

			cond_resched();

			goto retry;

		}
@@ -185,14 +173,12 @@ static void ipte_lock_siif(struct kvm *kvm) 
		new.k = 1;

		new.kh++;

	} while (!try_cmpxchg(&ic->val, &old.val, new.val));

	read_unlock(&kvm->arch.sca_lock);

}



static void ipte_unlock_siif(struct kvm *kvm)

{

	union ipte_control old, new, *ic;



	read_lock(&kvm->arch.sca_lock);

	ic = &kvm->arch.sca->ipte_control;

	old = READ_ONCE(*ic);

	do {
@@ -201,7 +187,6 @@ static void ipte_unlock_siif(struct kvm *kvm) 
		if (!new.kh)

			new.k = 0;

	} while (!try_cmpxchg(&ic->val, &old.val, new.val));

	read_unlock(&kvm->arch.sca_lock);

	if (!new.kh)

		wake_up(&kvm->arch.ipte_wq);

}

arch/s390/kvm/interrupt.c

+9 −27
Original line number Diff line number Diff line
@@ -45,48 +45,34 @@ static struct kvm_s390_gib *gib; 
/* handle external calls via sigp interpretation facility */

static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id)

{

	union esca_sigp_ctrl sigp_ctrl;

	struct esca_block *sca;

	int c, scn;

	struct esca_block *sca = vcpu->kvm->arch.sca;

	union esca_sigp_ctrl sigp_ctrl = sca->cpu[vcpu->vcpu_id].sigp_ctrl;



	if (!kvm_s390_test_cpuflags(vcpu, CPUSTAT_ECALL_PEND))

		return 0;



	BUG_ON(!kvm_s390_use_sca_entries());

	read_lock(&vcpu->kvm->arch.sca_lock);

	sca = vcpu->kvm->arch.sca;

	sigp_ctrl = sca->cpu[vcpu->vcpu_id].sigp_ctrl;



	c = sigp_ctrl.c;

	scn = sigp_ctrl.scn;

	read_unlock(&vcpu->kvm->arch.sca_lock);



	if (src_id)

		*src_id = scn;

		*src_id = sigp_ctrl.scn;



	return c;

	return sigp_ctrl.c;

}



static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id)

{

	union esca_sigp_ctrl old_val, new_val = {0};

	union esca_sigp_ctrl *sigp_ctrl;

	struct esca_block *sca;

	struct esca_block *sca = vcpu->kvm->arch.sca;

	union esca_sigp_ctrl *sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl;

	union esca_sigp_ctrl old_val, new_val = {.scn = src_id, .c = 1};

	int expect, rc;



	BUG_ON(!kvm_s390_use_sca_entries());

	read_lock(&vcpu->kvm->arch.sca_lock);

	sca = vcpu->kvm->arch.sca;

	sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl;



	old_val = READ_ONCE(*sigp_ctrl);

	new_val.scn = src_id;

	new_val.c = 1;

	old_val.c = 0;



	expect = old_val.value;

	rc = cmpxchg(&sigp_ctrl->value, old_val.value, new_val.value);

	read_unlock(&vcpu->kvm->arch.sca_lock);



	if (rc != expect) {

		/* another external call is pending */
@@ -98,18 +84,14 @@ static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id) 


static void sca_clear_ext_call(struct kvm_vcpu *vcpu)

{

	union esca_sigp_ctrl *sigp_ctrl;

	struct esca_block *sca;

	struct esca_block *sca = vcpu->kvm->arch.sca;

	union esca_sigp_ctrl *sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl;



	if (!kvm_s390_use_sca_entries())

		return;

	kvm_s390_clear_cpuflags(vcpu, CPUSTAT_ECALL_PEND);

	read_lock(&vcpu->kvm->arch.sca_lock);

	sca = vcpu->kvm->arch.sca;

	sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl;



	WRITE_ONCE(sigp_ctrl->value, 0);

	read_unlock(&vcpu->kvm->arch.sca_lock);

}



int psw_extint_disabled(struct kvm_vcpu *vcpu)

arch/s390/kvm/kvm-s390.c

+9 −25
Original line number Diff line number Diff line
@@ -1938,14 +1938,12 @@ static void kvm_s390_update_topology_change_report(struct kvm *kvm, bool val) 
	union sca_utility new, old;

	struct esca_block *sca;



	read_lock(&kvm->arch.sca_lock);

	sca = kvm->arch.sca;

	old = READ_ONCE(sca->utility);

	do {

		new = old;

		new.mtcr = val;

	} while (!try_cmpxchg(&sca->utility.val, &old.val, new.val));

	read_unlock(&kvm->arch.sca_lock);

}



static int kvm_s390_set_topo_change_indication(struct kvm *kvm,
@@ -1966,9 +1964,7 @@ static int kvm_s390_get_topo_change_indication(struct kvm *kvm, 
	if (!test_kvm_facility(kvm, 11))

		return -ENXIO;



	read_lock(&kvm->arch.sca_lock);

	topo = kvm->arch.sca->utility.mtcr;

	read_unlock(&kvm->arch.sca_lock);



	return put_user(topo, (u8 __user *)attr->addr);

}
@@ -3345,7 +3341,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) 


	if (!sclp.has_64bscao)

		alloc_flags |= GFP_DMA;

	rwlock_init(&kvm->arch.sca_lock);

	mutex_lock(&kvm_lock);



	kvm->arch.sca = alloc_pages_exact(sizeof(*kvm->arch.sca), alloc_flags);
@@ -3530,41 +3525,30 @@ static int __kvm_ucontrol_vcpu_init(struct kvm_vcpu *vcpu) 


static void sca_del_vcpu(struct kvm_vcpu *vcpu)

{

	struct esca_block *sca;

	struct esca_block *sca = vcpu->kvm->arch.sca;



	if (!kvm_s390_use_sca_entries())

		return;

	read_lock(&vcpu->kvm->arch.sca_lock);

	sca = vcpu->kvm->arch.sca;



	clear_bit_inv(vcpu->vcpu_id, (unsigned long *)sca->mcn);

	sca->cpu[vcpu->vcpu_id].sda = 0;

	read_unlock(&vcpu->kvm->arch.sca_lock);

}



static void sca_add_vcpu(struct kvm_vcpu *vcpu)

{

	struct esca_block *sca;

	phys_addr_t sca_phys;

	struct esca_block *sca = vcpu->kvm->arch.sca;

	phys_addr_t sca_phys = virt_to_phys(sca);



	if (!kvm_s390_use_sca_entries()) {

		sca_phys = virt_to_phys(vcpu->kvm->arch.sca);



		/* we still need the basic sca for the ipte control */

		vcpu->arch.sie_block->scaoh = sca_phys >> 32;

		vcpu->arch.sie_block->scaol = sca_phys;

		return;

	}

	read_lock(&vcpu->kvm->arch.sca_lock);

	sca = vcpu->kvm->arch.sca;

	sca_phys = virt_to_phys(sca);



	sca->cpu[vcpu->vcpu_id].sda = virt_to_phys(vcpu->arch.sie_block);

	/* we still need the sca header for the ipte control */

	vcpu->arch.sie_block->scaoh = sca_phys >> 32;

	vcpu->arch.sie_block->scaol = sca_phys & ESCA_SCAOL_MASK;

	vcpu->arch.sie_block->ecb2 |= ECB2_ESCA;



	if (!kvm_s390_use_sca_entries())

		return;



	set_bit_inv(vcpu->vcpu_id, (unsigned long *)sca->mcn);

	read_unlock(&vcpu->kvm->arch.sca_lock);

	sca->cpu[vcpu->vcpu_id].sda = virt_to_phys(vcpu->arch.sie_block);

}



static int sca_can_add_vcpu(struct kvm *kvm, unsigned int id)