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KVM: s390: Introduce switching code

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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: Eugene (jno) Dvurechenski <jno@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Eugene (jno) Dvurechenski 2015-04-22 18:08:39 +02:00 committed by Christian Borntraeger
parent 7d43bafcff
commit 5e04431523
4 changed files with 103 additions and 9 deletions
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1
arch/s390/include/asm/kvm_host.h
View File

@ -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;

30
arch/s390/kvm/gaccess.c
View File

@ -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);
}

6
arch/s390/kvm/interrupt.c
View File

@ -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? */
}

75
arch/s390/kvm/kvm-s390.c
View File

@ -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)