Archs are free to use vcpu_id as they see fit. For x86 it is used as
vcpu's apic id. New ioctl is added to configure boot vcpu id that was
assumed to be 0 till now.
Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
---
include/linux/kvm.h | 2 +
include/linux/kvm_host.h | 2 +
virt/kvm/kvm_main.c | 50 ++++++++++++++++++++++++++-------------------
3 files changed, 33 insertions(+), 21 deletions(-)
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 632a856..d10ab5d 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -430,6 +430,7 @@ struct kvm_trace_rec {
#ifdef __KVM_HAVE_PIT
#define KVM_CAP_PIT2 33
#endif
+#define KVM_CAP_SET_BOOT_CPU_ID 34
#ifdef KVM_CAP_IRQ_ROUTING
@@ -537,6 +538,7 @@ struct kvm_irqfd {
#define KVM_DEASSIGN_DEV_IRQ _IOW(KVMIO, 0x75, struct kvm_assigned_irq)
#define KVM_IRQFD _IOW(KVMIO, 0x76, struct kvm_irqfd)
#define KVM_CREATE_PIT2 _IOW(KVMIO, 0x77, struct kvm_pit_config)
+#define KVM_SET_BOOT_CPU_ID _IO(KVMIO, 0x78)
/*
* ioctls for vcpu fds
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index e9e0cd8..e368a14 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -130,8 +130,10 @@ struct kvm {
int nmemslots;
struct kvm_memory_slot memslots[KVM_MEMORY_SLOTS +
KVM_PRIVATE_MEM_SLOTS];
+ u32 bsp_vcpu_id;
struct kvm_vcpu *bsp_vcpu;
struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
+ atomic_t online_vcpus;
struct list_head vm_list;
struct kvm_io_bus mmio_bus;
struct kvm_io_bus pio_bus;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5a55fe0..d65c637 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -693,11 +693,6 @@ out:
}
#endif
-static inline int valid_vcpu(int n)
-{
- return likely(n >= 0 && n < KVM_MAX_VCPUS);
-}
-
inline int kvm_is_mmio_pfn(pfn_t pfn)
{
if (pfn_valid(pfn)) {
@@ -1713,15 +1708,12 @@ static int create_vcpu_fd(struct kvm_vcpu *vcpu)
/*
* Creates some virtual cpus. Good luck creating more than one.
*/
-static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
+static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
{
int r;
struct kvm_vcpu *vcpu;
- if (!valid_vcpu(n))
- return -EINVAL;
-
- vcpu = kvm_arch_vcpu_create(kvm, n);
+ vcpu = kvm_arch_vcpu_create(kvm, id);
if (IS_ERR(vcpu))
return PTR_ERR(vcpu);
@@ -1732,25 +1724,36 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
return r;
mutex_lock(&kvm->lock);
- if (kvm->vcpus[n]) {
- r = -EEXIST;
+ if (atomic_read(&kvm->online_vcpus) == KVM_MAX_VCPUS) {
+ r = -EINVAL;
goto vcpu_destroy;
}
- kvm->vcpus[n] = vcpu;
- if (n == 0)
- kvm->bsp_vcpu = vcpu;
- mutex_unlock(&kvm->lock);
+
+ for (r = 0; r < atomic_read(&kvm->online_vcpus); r++)
+ if (kvm->vcpus[r]->vcpu_id == id) {
+ r = -EEXIST;
+ goto vcpu_destroy;
+ }
+
+ BUG_ON(kvm->vcpus[atomic_read(&kvm->online_vcpus)]);
/* Now it's all set up, let userspace reach it */
kvm_get_kvm(kvm);
r = create_vcpu_fd(vcpu);
- if (r < 0)
- goto unlink;
+ if (r < 0) {
+ kvm_put_kvm(kvm);
+ goto vcpu_destroy;
+ }
+
+ kvm->vcpus[atomic_read(&kvm->online_vcpus)] = vcpu;
+ smp_wmb();
+ atomic_inc(&kvm->online_vcpus);
+
+ if (kvm->bsp_vcpu_id == id)
+ kvm->bsp_vcpu = vcpu;
+ mutex_unlock(&kvm->lock);
return r;
-unlink:
- mutex_lock(&kvm->lock);
- kvm->vcpus[n] = NULL;
vcpu_destroy:
mutex_unlock(&kvm->lock);
kvm_arch_vcpu_destroy(vcpu);
@@ -2223,6 +2226,10 @@ static long kvm_vm_ioctl(struct file *filp,
r = kvm_irqfd(kvm, data.fd, data.gsi, data.flags);
break;
}
+ case KVM_SET_BOOT_CPU_ID:
+ kvm->bsp_vcpu_id = arg;
+ r = 0;
+ break;
default:
r = kvm_arch_vm_ioctl(filp, ioctl, arg);
}
@@ -2289,6 +2296,7 @@ static long kvm_dev_ioctl_check_extension_generic(long arg)
case KVM_CAP_USER_MEMORY:
case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
case KVM_CAP_JOIN_MEMORY_REGIONS_WORKS:
+ case KVM_CAP_SET_BOOT_CPU_ID:
return 1;
#ifdef CONFIG_HAVE_KVM_IRQCHIP
case KVM_CAP_IRQ_ROUTING:
--
1.6.2.1
--
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