KVM: Break dependency between vcpu index in vcpus array and vcpu_id.

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@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/ia64/include/asm/kvm_host.h b/arch/ia64/include/asm/kvm_host.h
index 5f43697..9cf1c4b 100644 (file)
--- a/arch/ia64/include/asm/kvm_host.h
+++ b/arch/ia64/include/asm/kvm_host.h
@@ -465,7 +465,6 @@ struct kvm_arch {
        unsigned long   metaphysical_rr4;
        unsigned long   vmm_init_rr;
 
-       int             online_vcpus;
        int             is_sn2;
 
        struct kvm_ioapic *vioapic;

diff --git a/arch/ia64/kvm/Kconfig b/arch/ia64/kvm/Kconfig
index f922bbb..cbadd8a 100644 (file)
--- a/arch/ia64/kvm/Kconfig
+++ b/arch/ia64/kvm/Kconfig
@@ -25,6 +25,7 @@ config KVM
        select PREEMPT_NOTIFIERS
        select ANON_INODES
        select HAVE_KVM_IRQCHIP
+       select KVM_APIC_ARCHITECTURE
        ---help---
          Support hosting fully virtualized guest machines using hardware
          virtualization extensions.  You will need a fairly recent

diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 4082665..d1f7bcd 100644 (file)
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -338,7 +338,7 @@ static struct kvm_vcpu *lid_to_vcpu(struct kvm *kvm, unsigned long id,
        union ia64_lid lid;
        int i;
 
-       for (i = 0; i < kvm->arch.online_vcpus; i++) {
+       for (i = 0; i < atomic_read(&kvm->online_vcpus); i++) {
                if (kvm->vcpus[i]) {
                        lid.val = VCPU_LID(kvm->vcpus[i]);
                        if (lid.id == id && lid.eid == eid)
@@ -412,7 +412,7 @@ static int handle_global_purge(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 
        call_data.ptc_g_data = p->u.ptc_g_data;
 
-       for (i = 0; i < kvm->arch.online_vcpus; i++) {
+       for (i = 0; i < atomic_read(&kvm->online_vcpus); i++) {
                if (!kvm->vcpus[i] || kvm->vcpus[i]->arch.mp_state ==
                                                KVM_MP_STATE_UNINITIALIZED ||
                                        vcpu == kvm->vcpus[i])
@@ -852,8 +852,6 @@ struct  kvm *kvm_arch_create_vm(void)
 
        kvm_init_vm(kvm);
 
-       kvm->arch.online_vcpus = 0;
-
        return kvm;
 
 }
@@ -1356,8 +1354,6 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
                goto fail;
        }
 
-       kvm->arch.online_vcpus++;
-
        return vcpu;
 fail:
        return ERR_PTR(r);

diff --git a/arch/ia64/kvm/vcpu.c b/arch/ia64/kvm/vcpu.c
index 61a3320..dce75b7 100644 (file)
--- a/arch/ia64/kvm/vcpu.c
+++ b/arch/ia64/kvm/vcpu.c
@@ -831,7 +831,7 @@ static void vcpu_set_itc(struct kvm_vcpu *vcpu, u64 val)
        kvm = (struct kvm *)KVM_VM_BASE;
 
        if (kvm_vcpu_is_bsp(vcpu)) {
-               for (i = 0; i < kvm->arch.online_vcpus; i++) {
+               for (i = 0; i < atomic_read(&kvm->online_vcpus); i++) {
                        v = (struct kvm_vcpu *)((char *)vcpu +
                                        sizeof(struct kvm_vcpu_data) * i);
                        VMX(v, itc_offset) = itc_offset;

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 8cd2a4e..7fbedfd 100644 (file)
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -27,6 +27,7 @@ config KVM
        select ANON_INODES
        select HAVE_KVM_IRQCHIP
        select HAVE_KVM_EVENTFD
+       select KVM_APIC_ARCHITECTURE
        ---help---
          Support hosting fully virtualized guest machines using hardware
          virtualization extensions.  You will need a fairly recent

diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index f1dada0..5037e17 100644 (file)
--- 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 a5bd429..d3fdf1a 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -131,8 +131,12 @@ struct kvm {
        int nmemslots;
        struct kvm_memory_slot memslots[KVM_MEMORY_SLOTS +
                                        KVM_PRIVATE_MEM_SLOTS];
+#ifdef CONFIG_KVM_APIC_ARCHITECTURE
+       u32 bsp_vcpu_id;
        struct kvm_vcpu *bsp_vcpu;
+#endif
        struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
+       atomic_t online_vcpus;
        struct list_head vm_list;
        struct mutex lock;
        struct kvm_io_bus mmio_bus;
@@ -550,8 +554,10 @@ static inline void kvm_irqfd_release(struct kvm *kvm) {}
 
 #endif /* CONFIG_HAVE_KVM_EVENTFD */
 
+#ifdef CONFIG_KVM_APIC_ARCHITECTURE
 static inline bool kvm_vcpu_is_bsp(struct kvm_vcpu *vcpu)
 {
        return vcpu->kvm->bsp_vcpu == vcpu;
 }
 #endif
+#endif

diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index 56c6848..daece36 100644 (file)
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -9,3 +9,6 @@ config HAVE_KVM_IRQCHIP
 config HAVE_KVM_EVENTFD
        bool
        select EVENTFD
+
+config KVM_APIC_ARCHITECTURE
+       bool

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0d54ede..25e1f9c 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -689,11 +689,6 @@ 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)) {
@@ -1714,24 +1709,18 @@ static struct file_operations kvm_vcpu_fops = {
  */
 static int create_vcpu_fd(struct kvm_vcpu *vcpu)
 {
-       int fd = anon_inode_getfd("kvm-vcpu", &kvm_vcpu_fops, vcpu, 0);
-       if (fd < 0)
-               kvm_put_kvm(vcpu->kvm);
-       return fd;
+       return anon_inode_getfd("kvm-vcpu", &kvm_vcpu_fops, vcpu, 0);
 }
 
 /*
  * 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);
 
@@ -1742,25 +1731,38 @@ 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);
+
+#ifdef CONFIG_KVM_APIC_ARCHITECTURE
+       if (kvm->bsp_vcpu_id == id)
+               kvm->bsp_vcpu = vcpu;
+#endif
+       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);
@@ -2233,6 +2235,15 @@ static long kvm_vm_ioctl(struct file *filp,
                r = kvm_irqfd(kvm, data.fd, data.gsi, data.flags);
                break;
        }
+#ifdef CONFIG_KVM_APIC_ARCHITECTURE
+       case KVM_SET_BOOT_CPU_ID:
+               r = 0;
+               if (atomic_read(&kvm->online_vcpus) != 0)
+                       r = -EBUSY;
+               else
+                       kvm->bsp_vcpu_id = arg;
+               break;
+#endif
        default:
                r = kvm_arch_vm_ioctl(filp, ioctl, arg);
        }
@@ -2299,6 +2310,9 @@ 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:
+#ifdef CONFIG_KVM_APIC_ARCHITECTURE
+       case KVM_CAP_SET_BOOT_CPU_ID:
+#endif
                return 1;
 #ifdef CONFIG_HAVE_KVM_IRQCHIP
        case KVM_CAP_IRQ_ROUTING: