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Subject[PATCH 47/48] KVM: Break dependency between vcpu index in vcpus array and vcpu_id.
Date
From: Gleb Natapov <gleb@redhat.com>

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>
---
arch/ia64/include/asm/kvm_host.h | 1 -
arch/ia64/kvm/Kconfig | 1 +
arch/ia64/kvm/kvm-ia64.c | 8 +---
arch/ia64/kvm/vcpu.c | 2 +-
arch/x86/kvm/Kconfig | 1 +
include/linux/kvm.h | 2 +
include/linux/kvm_host.h | 6 +++
virt/kvm/Kconfig | 3 ++
virt/kvm/kvm_main.c | 64 +++++++++++++++++++++++---------------
9 files changed, 55 insertions(+), 33 deletions(-)

diff --git a/arch/ia64/include/asm/kvm_host.h b/arch/ia64/include/asm/kvm_host.h
index 5f43697..9cf1c4b 100644
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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:
--
1.6.3.3


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