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Commit 5e044315 authored by Eugene (jno) Dvurechenski's avatar Eugene (jno) Dvurechenski Committed by Christian Borntraeger
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KVM: s390: Introduce switching code 



This patch adds code that performs transparent switch to Extended
SCA on addition of 65th VCPU in a VM. Disposal of ESCA is added too.
The entier ESCA functionality, however, is still not enabled.
The enablement will be provided in a separate patch.

This patch also uses read/write lock protection of SCA and its subfields for
possible disposal at the BSCA-to-ESCA transition. While only Basic SCA needs such
a protection (for the swap), any SCA access is now guarded.

Signed-off-by: default avatarEugene (jno) Dvurechenski <jno@linux.vnet.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent 7d43bafc

arch/s390/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -622,6 +622,7 @@ struct kvm_s390_crypto_cb { 
struct kvm_arch{

	void *sca;

	int use_esca;

	rwlock_t sca_lock;

	debug_info_t *dbf;

	struct kvm_s390_float_interrupt float_int;

	struct kvm_device *flic;

arch/s390/kvm/gaccess.c

+23 −7
Original line number Diff line number Diff line
@@ -259,10 +259,14 @@ struct aste { 


int ipte_lock_held(struct kvm_vcpu *vcpu)

{

	union ipte_control *ic = kvm_s390_get_ipte_control(vcpu->kvm);

	if (vcpu->arch.sie_block->eca & 1) {

		int rc;



	if (vcpu->arch.sie_block->eca & 1)

		return ic->kh != 0;

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

		rc = kvm_s390_get_ipte_control(vcpu->kvm)->kh != 0;

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

		return rc;

	}

	return vcpu->kvm->arch.ipte_lock_count != 0;

}
@@ -274,16 +278,20 @@ static void ipte_lock_simple(struct kvm_vcpu *vcpu) 
	vcpu->kvm->arch.ipte_lock_count++;

	if (vcpu->kvm->arch.ipte_lock_count > 1)

		goto out;

retry:

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

	ic = kvm_s390_get_ipte_control(vcpu->kvm);

	do {

		old = READ_ONCE(*ic);

		while (old.k) {

		if (old.k) {

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

			cond_resched();

			old = READ_ONCE(*ic);

			goto retry;

		}

		new = old;

		new.k = 1;

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

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

out:

	mutex_unlock(&vcpu->kvm->arch.ipte_mutex);

}
@@ -296,12 +304,14 @@ static void ipte_unlock_simple(struct kvm_vcpu *vcpu) 
	vcpu->kvm->arch.ipte_lock_count--;

	if (vcpu->kvm->arch.ipte_lock_count)

		goto out;

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

	ic = kvm_s390_get_ipte_control(vcpu->kvm);

	do {

		old = READ_ONCE(*ic);

		new = old;

		new.k = 0;

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

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

	wake_up(&vcpu->kvm->arch.ipte_wq);

out:

	mutex_unlock(&vcpu->kvm->arch.ipte_mutex);
@@ -311,23 +321,28 @@ static void ipte_lock_siif(struct kvm_vcpu *vcpu) 
{

	union ipte_control old, new, *ic;



retry:

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

	ic = kvm_s390_get_ipte_control(vcpu->kvm);

	do {

		old = READ_ONCE(*ic);

		while (old.kg) {

		if (old.kg) {

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

			cond_resched();

			old = READ_ONCE(*ic);

			goto retry;

		}

		new = old;

		new.k = 1;

		new.kh++;

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

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

}



static void ipte_unlock_siif(struct kvm_vcpu *vcpu)

{

	union ipte_control old, new, *ic;



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

	ic = kvm_s390_get_ipte_control(vcpu->kvm);

	do {

		old = READ_ONCE(*ic);
@@ -336,6 +351,7 @@ static void ipte_unlock_siif(struct kvm_vcpu *vcpu) 
		if (!new.kh)

			new.k = 0;

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

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

	if (!new.kh)

		wake_up(&vcpu->kvm->arch.ipte_wq);

}

arch/s390/kvm/interrupt.c

+6 −0
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id) 
{

	int c, scn;



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

	if (vcpu->kvm->arch.use_esca) {

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

		union esca_sigp_ctrl sigp_ctrl =
@@ -54,6 +55,7 @@ static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id) 
		c = sigp_ctrl.c;

		scn = sigp_ctrl.scn;

	}

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



	if (src_id)

		*src_id = scn;
@@ -66,6 +68,7 @@ static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id) 
{

	int expect, rc;



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

	if (vcpu->kvm->arch.use_esca) {

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

		union esca_sigp_ctrl *sigp_ctrl =
@@ -91,6 +94,7 @@ static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id) 
		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 */
@@ -106,6 +110,7 @@ static void sca_clear_ext_call(struct kvm_vcpu *vcpu) 
	int rc, expect;



	atomic_andnot(CPUSTAT_ECALL_PEND, li->cpuflags);

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

	if (vcpu->kvm->arch.use_esca) {

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

		union esca_sigp_ctrl *sigp_ctrl =
@@ -123,6 +128,7 @@ static void sca_clear_ext_call(struct kvm_vcpu *vcpu) 
		expect = old.value;

		rc = cmpxchg(&sigp_ctrl->value, old.value, 0);

	}

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

	WARN_ON(rc != expect); /* cannot clear? */

}

arch/s390/kvm/kvm-s390.c

+73 −2
Original line number Diff line number Diff line
@@ -1080,7 +1080,7 @@ static int kvm_s390_crypto_init(struct kvm *kvm) 
static void sca_dispose(struct kvm *kvm)

{

	if (kvm->arch.use_esca)

		BUG(); /* not implemented yet */

		free_pages_exact(kvm->arch.sca, sizeof(struct esca_block));

	else

		free_page((unsigned long)(kvm->arch.sca));

	kvm->arch.sca = NULL;
@@ -1110,6 +1110,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) 
	rc = -ENOMEM;



	kvm->arch.use_esca = 0; /* start with basic SCA */

	rwlock_init(&kvm->arch.sca_lock);

	kvm->arch.sca = (struct bsca_block *) get_zeroed_page(GFP_KERNEL);

	if (!kvm->arch.sca)

		goto out_err;
@@ -1259,6 +1260,7 @@ static int __kvm_ucontrol_vcpu_init(struct kvm_vcpu *vcpu) 


static void sca_del_vcpu(struct kvm_vcpu *vcpu)

{

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

	if (vcpu->kvm->arch.use_esca) {

		struct esca_block *sca = vcpu->kvm->arch.sca;
@@ -1272,11 +1274,13 @@ static void sca_del_vcpu(struct kvm_vcpu *vcpu) 
		if (sca->cpu[vcpu->vcpu_id].sda == (__u64) vcpu->arch.sie_block)

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

	}

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

}



static void sca_add_vcpu(struct kvm_vcpu *vcpu, struct kvm *kvm,

			unsigned int id)

{

	read_lock(&kvm->arch.sca_lock);

	if (kvm->arch.use_esca) {

		struct esca_block *sca = kvm->arch.sca;
@@ -1294,11 +1298,78 @@ static void sca_add_vcpu(struct kvm_vcpu *vcpu, struct kvm *kvm, 
		vcpu->arch.sie_block->scaol = (__u32)(__u64)sca;

		set_bit_inv(id, (unsigned long *) &sca->mcn);

	}

	read_unlock(&kvm->arch.sca_lock);

}



/* Basic SCA to Extended SCA data copy routines */

static inline void sca_copy_entry(struct esca_entry *d, struct bsca_entry *s)

{

	d->sda = s->sda;

	d->sigp_ctrl.c = s->sigp_ctrl.c;

	d->sigp_ctrl.scn = s->sigp_ctrl.scn;

}



static void sca_copy_b_to_e(struct esca_block *d, struct bsca_block *s)

{

	int i;



	d->ipte_control = s->ipte_control;

	d->mcn[0] = s->mcn;

	for (i = 0; i < KVM_S390_BSCA_CPU_SLOTS; i++)

		sca_copy_entry(&d->cpu[i], &s->cpu[i]);

}



static int sca_switch_to_extended(struct kvm *kvm)

{

	struct bsca_block *old_sca = kvm->arch.sca;

	struct esca_block *new_sca;

	struct kvm_vcpu *vcpu;

	unsigned int vcpu_idx;

	u32 scaol, scaoh;



	new_sca = alloc_pages_exact(sizeof(*new_sca), GFP_KERNEL|__GFP_ZERO);

	if (!new_sca)

		return -ENOMEM;



	scaoh = (u32)((u64)(new_sca) >> 32);

	scaol = (u32)(u64)(new_sca) & ~0x3fU;



	kvm_s390_vcpu_block_all(kvm);

	write_lock(&kvm->arch.sca_lock);



	sca_copy_b_to_e(new_sca, old_sca);



	kvm_for_each_vcpu(vcpu_idx, vcpu, kvm) {

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

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

		vcpu->arch.sie_block->ecb2 |= 0x04U;

	}

	kvm->arch.sca = new_sca;

	kvm->arch.use_esca = 1;



	write_unlock(&kvm->arch.sca_lock);

	kvm_s390_vcpu_unblock_all(kvm);



	free_page((unsigned long)old_sca);



	VM_EVENT(kvm, 2, "Switched to ESCA (%p -> %p)", old_sca, kvm->arch.sca);

	return 0;

}



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

{

	return id < KVM_MAX_VCPUS;

	int rc;



	if (id < KVM_S390_BSCA_CPU_SLOTS)

		return true;

	if (!sclp.has_esca)

		return false;



	mutex_lock(&kvm->lock);

	rc = kvm->arch.use_esca ? 0 : sca_switch_to_extended(kvm);

	mutex_unlock(&kvm->lock);



	return rc == 0 && id < KVM_S390_ESCA_CPU_SLOTS;

}



int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)