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KVM: S390: Remove sca_lock

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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: Christoph Schlameuss <schlameuss@linux.ibm.com>
Suggested-by: Janosch Frank <frankja@linux.ibm.com>
[frankja@linux.ibm.com: Added suggested-by tag as discussed on list]
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
This commit is contained in:
Christoph Schlameuss 2025-06-05 18:14:05 +02:00 committed by Janosch Frank
parent e72753ed12
commit 14542a0a54
4 changed files with 20 additions and 70 deletions
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1
arch/s390/include/asm/kvm_host.h
View File

@ -633,7 +633,6 @@ struct kvm_s390_pv {
struct kvm_arch { struct kvm_arch {
struct esca_block *sca; struct esca_block *sca;
rwlock_t sca_lock;
debug_info_t *dbf; debug_info_t *dbf;
struct kvm_s390_float_interrupt float_int; struct kvm_s390_float_interrupt float_int;
struct kvm_device *flic; struct kvm_device *flic;

19
arch/s390/kvm/gaccess.c
View File

@ -109,14 +109,9 @@ struct aste {
int ipte_lock_held(struct kvm *kvm) int ipte_lock_held(struct kvm *kvm)
{ {
if (sclp.has_siif) { if (sclp.has_siif)
int rc; 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; 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) if (kvm->arch.ipte_lock_count > 1)
goto out; goto out;
retry: retry:
read_lock(&kvm->arch.sca_lock);
ic = &kvm->arch.sca->ipte_control; ic = &kvm->arch.sca->ipte_control;
old = READ_ONCE(*ic); old = READ_ONCE(*ic);
do { do {
if (old.k) { if (old.k) {
read_unlock(&kvm->arch.sca_lock);
cond_resched(); cond_resched();
goto retry; goto retry;
} }
new = old; new = old;
new.k = 1; new.k = 1;
} while (!try_cmpxchg(&ic->val, &old.val, new.val)); } while (!try_cmpxchg(&ic->val, &old.val, new.val));
read_unlock(&kvm->arch.sca_lock);
out: out:
mutex_unlock(&kvm->arch.ipte_mutex); mutex_unlock(&kvm->arch.ipte_mutex);
} }
@ -154,14 +146,12 @@ static void ipte_unlock_simple(struct kvm *kvm)
kvm->arch.ipte_lock_count--; kvm->arch.ipte_lock_count--;
if (kvm->arch.ipte_lock_count) if (kvm->arch.ipte_lock_count)
goto out; goto out;
read_lock(&kvm->arch.sca_lock);
ic = &kvm->arch.sca->ipte_control; ic = &kvm->arch.sca->ipte_control;
old = READ_ONCE(*ic); old = READ_ONCE(*ic);
do { do {
new = old; new = old;
new.k = 0; new.k = 0;
} while (!try_cmpxchg(&ic->val, &old.val, new.val)); } while (!try_cmpxchg(&ic->val, &old.val, new.val));
read_unlock(&kvm->arch.sca_lock);
wake_up(&kvm->arch.ipte_wq); wake_up(&kvm->arch.ipte_wq);
out: out:
mutex_unlock(&kvm->arch.ipte_mutex); mutex_unlock(&kvm->arch.ipte_mutex);
@ -172,12 +162,10 @@ static void ipte_lock_siif(struct kvm *kvm)
union ipte_control old, new, *ic; union ipte_control old, new, *ic;
retry: retry:
read_lock(&kvm->arch.sca_lock);
ic = &kvm->arch.sca->ipte_control; ic = &kvm->arch.sca->ipte_control;
old = READ_ONCE(*ic); old = READ_ONCE(*ic);
do { do {
if (old.kg) { if (old.kg) {
read_unlock(&kvm->arch.sca_lock);
cond_resched(); cond_resched();
goto retry; goto retry;
} }
@ -185,14 +173,12 @@ static void ipte_lock_siif(struct kvm *kvm)
new.k = 1; new.k = 1;
new.kh++; new.kh++;
} while (!try_cmpxchg(&ic->val, &old.val, new.val)); } while (!try_cmpxchg(&ic->val, &old.val, new.val));
read_unlock(&kvm->arch.sca_lock);
} }
static void ipte_unlock_siif(struct kvm *kvm) static void ipte_unlock_siif(struct kvm *kvm)
{ {
union ipte_control old, new, *ic; union ipte_control old, new, *ic;
read_lock(&kvm->arch.sca_lock);
ic = &kvm->arch.sca->ipte_control; ic = &kvm->arch.sca->ipte_control;
old = READ_ONCE(*ic); old = READ_ONCE(*ic);
do { do {
@ -201,7 +187,6 @@ static void ipte_unlock_siif(struct kvm *kvm)
if (!new.kh) if (!new.kh)
new.k = 0; new.k = 0;
} while (!try_cmpxchg(&ic->val, &old.val, new.val)); } while (!try_cmpxchg(&ic->val, &old.val, new.val));
read_unlock(&kvm->arch.sca_lock);
if (!new.kh) if (!new.kh)
wake_up(&kvm->arch.ipte_wq); wake_up(&kvm->arch.ipte_wq);
} }

36
arch/s390/kvm/interrupt.c
View File

@ -45,48 +45,34 @@ static struct kvm_s390_gib *gib;
/* handle external calls via sigp interpretation facility */ /* handle external calls via sigp interpretation facility */
static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id) static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id)
{ {
union esca_sigp_ctrl sigp_ctrl; struct esca_block *sca = vcpu->kvm->arch.sca;
struct esca_block *sca; union esca_sigp_ctrl sigp_ctrl = sca->cpu[vcpu->vcpu_id].sigp_ctrl;
int c, scn;
if (!kvm_s390_test_cpuflags(vcpu, CPUSTAT_ECALL_PEND)) if (!kvm_s390_test_cpuflags(vcpu, CPUSTAT_ECALL_PEND))
return 0; return 0;
BUG_ON(!kvm_s390_use_sca_entries()); 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) 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) static int sca_inject_ext_call(struct kvm_vcpu *vcpu, int src_id)
{ {
union esca_sigp_ctrl old_val, new_val = {0}; struct esca_block *sca = vcpu->kvm->arch.sca;
union esca_sigp_ctrl *sigp_ctrl; union esca_sigp_ctrl *sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl;
struct esca_block *sca; union esca_sigp_ctrl old_val, new_val = {.scn = src_id, .c = 1};
int expect, rc; int expect, rc;
BUG_ON(!kvm_s390_use_sca_entries()); 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); old_val = READ_ONCE(*sigp_ctrl);
new_val.scn = src_id;
new_val.c = 1;
old_val.c = 0; old_val.c = 0;
expect = old_val.value; expect = old_val.value;
rc = cmpxchg(&sigp_ctrl->value, old_val.value, new_val.value); rc = cmpxchg(&sigp_ctrl->value, old_val.value, new_val.value);
read_unlock(&vcpu->kvm->arch.sca_lock);
if (rc != expect) { if (rc != expect) {
/* another external call is pending */ /* 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) static void sca_clear_ext_call(struct kvm_vcpu *vcpu)
{ {
union esca_sigp_ctrl *sigp_ctrl; struct esca_block *sca = vcpu->kvm->arch.sca;
struct esca_block *sca; union esca_sigp_ctrl *sigp_ctrl = &sca->cpu[vcpu->vcpu_id].sigp_ctrl;
if (!kvm_s390_use_sca_entries()) if (!kvm_s390_use_sca_entries())
return; return;
kvm_s390_clear_cpuflags(vcpu, CPUSTAT_ECALL_PEND); 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); WRITE_ONCE(sigp_ctrl->value, 0);
read_unlock(&vcpu->kvm->arch.sca_lock);
} }
int psw_extint_disabled(struct kvm_vcpu *vcpu) int psw_extint_disabled(struct kvm_vcpu *vcpu)

34
arch/s390/kvm/kvm-s390.c
View File

@ -1938,14 +1938,12 @@ static void kvm_s390_update_topology_change_report(struct kvm *kvm, bool val)
union sca_utility new, old; union sca_utility new, old;
struct esca_block *sca; struct esca_block *sca;
read_lock(&kvm->arch.sca_lock);
sca = kvm->arch.sca; sca = kvm->arch.sca;
old = READ_ONCE(sca->utility); old = READ_ONCE(sca->utility);
do { do {
new = old; new = old;
new.mtcr = val; new.mtcr = val;
} while (!try_cmpxchg(&sca->utility.val, &old.val, new.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, 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)) if (!test_kvm_facility(kvm, 11))
return -ENXIO; return -ENXIO;
read_lock(&kvm->arch.sca_lock);
topo = kvm->arch.sca->utility.mtcr; topo = kvm->arch.sca->utility.mtcr;
read_unlock(&kvm->arch.sca_lock);
return put_user(topo, (u8 __user *)attr->addr); 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) if (!sclp.has_64bscao)
alloc_flags |= GFP_DMA; alloc_flags |= GFP_DMA;
rwlock_init(&kvm->arch.sca_lock);
mutex_lock(&kvm_lock); mutex_lock(&kvm_lock);
kvm->arch.sca = alloc_pages_exact(sizeof(*kvm->arch.sca), alloc_flags); 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) 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()) if (!kvm_s390_use_sca_entries())
return; return;
read_lock(&vcpu->kvm->arch.sca_lock);
sca = vcpu->kvm->arch.sca;
clear_bit_inv(vcpu->vcpu_id, (unsigned long *)sca->mcn); clear_bit_inv(vcpu->vcpu_id, (unsigned long *)sca->mcn);
sca->cpu[vcpu->vcpu_id].sda = 0; sca->cpu[vcpu->vcpu_id].sda = 0;
read_unlock(&vcpu->kvm->arch.sca_lock);
} }
static void sca_add_vcpu(struct kvm_vcpu *vcpu) static void sca_add_vcpu(struct kvm_vcpu *vcpu)
{ {
struct esca_block *sca; struct esca_block *sca = vcpu->kvm->arch.sca;
phys_addr_t sca_phys; phys_addr_t sca_phys = virt_to_phys(sca);
if (!kvm_s390_use_sca_entries()) { /* we still need the sca header for the ipte control */
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);
vcpu->arch.sie_block->scaoh = sca_phys >> 32; vcpu->arch.sie_block->scaoh = sca_phys >> 32;
vcpu->arch.sie_block->scaol = sca_phys & ESCA_SCAOL_MASK; vcpu->arch.sie_block->scaol = sca_phys & ESCA_SCAOL_MASK;
vcpu->arch.sie_block->ecb2 |= ECB2_ESCA; vcpu->arch.sie_block->ecb2 |= ECB2_ESCA;
if (!kvm_s390_use_sca_entries())
return;
set_bit_inv(vcpu->vcpu_id, (unsigned long *)sca->mcn); 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) static int sca_can_add_vcpu(struct kvm *kvm, unsigned int id)