Am 06.05.24 um 12:17 schrieb Yi Wang:
From: Yi Wang <foxywang@xxxxxxxxxxx>
Add a new function to setup empty irq routing in kvm path, which
can be invoded in non-architecture-specific functions. The difference
compared to the kvm_setup_empty_irq_routing() is this function just
alloc the empty irq routing and does not need synchronize srcu, as
we will call it in kvm_create_vm().
Using the new adding function, we can setup empty irq routing when
kvm_create_vm(), so that x86 and s390 no longer need to set
empty/dummy irq routing when creating an IRQCHIP 'cause it avoid
an synchronize_srcu.
Signed-off-by: Yi Wang <foxywang@xxxxxxxxxxx>
Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
---
include/linux/kvm_host.h | 2 ++
virt/kvm/irqchip.c | 23 +++++++++++++++++++++++
virt/kvm/kvm_main.c | 9 ++++++++-
3 files changed, 33 insertions(+), 1 deletion(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 48f31dcd318a..a5f12b667ca5 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2100,6 +2100,7 @@ int kvm_set_irq_routing(struct kvm *kvm,
const struct kvm_irq_routing_entry *entries,
unsigned nr,
unsigned flags);
+int kvm_init_irq_routing(struct kvm *kvm);
int kvm_set_routing_entry(struct kvm *kvm,
struct kvm_kernel_irq_routing_entry *e,
const struct kvm_irq_routing_entry *ue);
@@ -2108,6 +2109,7 @@ void kvm_free_irq_routing(struct kvm *kvm);
#else
static inline void kvm_free_irq_routing(struct kvm *kvm) {}
+int kvm_init_irq_routing(struct kvm *kvm) {}
#endif
diff --git a/virt/kvm/irqchip.c b/virt/kvm/irqchip.c
index 1e567d1f6d3d..ec1fda7fffea 100644
--- a/virt/kvm/irqchip.c
+++ b/virt/kvm/irqchip.c
@@ -237,3 +237,26 @@ int kvm_set_irq_routing(struct kvm *kvm,
return r;
}
+
+/*
+ * Alloc empty irq routing.
+ * Called only during vm creation, because we don't synchronize_srcu here.
+ */
+int kvm_init_irq_routing(struct kvm *kvm)
+{
+ struct kvm_irq_routing_table *new;
+ int chip_size;
+
+ new = kzalloc(struct_size(new, map, 1), GFP_KERNEL_ACCOUNT);
+ if (!new)
+ return -ENOMEM;
+
+ new->nr_rt_entries = 1;
+
+ chip_size = sizeof(int) * KVM_NR_IRQCHIPS * KVM_IRQCHIP_NUM_PINS;
+ memset(new->chip, -1, chip_size);
+
+ RCU_INIT_POINTER(kvm->irq_routing, new);
+
+ return 0;
+}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ff0a20565f90..4100ebdd14fe 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1233,6 +1233,11 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
goto out_err_no_irq_srcu;
refcount_set(&kvm->users_count, 1);
+
+ r = kvm_init_irq_routing(kvm);
+ if (r)
+ goto out_err_no_irq_routing;
+
for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) {
for (j = 0; j < 2; j++) {
slots = &kvm->__memslots[i][j];
@@ -1308,9 +1313,11 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
out_err_no_disable:
kvm_arch_destroy_vm(kvm);
out_err_no_arch_destroy_vm:
- WARN_ON_ONCE(!refcount_dec_and_test(&kvm->users_count));
for (i = 0; i < KVM_NR_BUSES; i++)
kfree(kvm_get_bus(kvm, i));
+ kvm_free_irq_routing(kvm);
+out_err_no_irq_routing:
+ WARN_ON_ONCE(!refcount_dec_and_test(&kvm->users_count));
cleanup_srcu_struct(&kvm->irq_srcu);
out_err_no_irq_srcu:
cleanup_srcu_struct(&kvm->srcu);
