[PATCH v2 13/13] KVM: x86: bump KVM_MAX_VCPU_ID to 1023

Radim Krčmář
2016-07-07T17:15:50Z

kzalloc was replaced with kvm_kvzalloc to allow non-contiguous areas and
rcu had to be modified to cope with it.

The practical limit for KVM_MAX_VCPU_ID right now is INT_MAX, but lower
value was chosen in case there were bugs. 1023 is sufficient maximum
APIC ID for 288 VCPUs.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
v2: new [Paolo]

arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/lapic.c | 13 ++++++++++---
arch/x86/kvm/x86.c | 2 +-
3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e362de872139..b771667e8e99 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -36,6 +36,7 @@

#define KVM_MAX_VCPUS 288
#define KVM_SOFT_MAX_VCPUS 240
+#define KVM_MAX_VCPU_ID 1023
#define KVM_USER_MEM_SLOTS 509
/* memory slots that are not exposed to userspace */
#define KVM_PRIVATE_MEM_SLOTS 3
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index b47a82bfc8c4..3fcc590aa155 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -147,6 +147,13 @@ static inline bool kvm_apic_map_get_logical_dest(struct kvm_apic_map *map,
}
}

+static void kvm_apic_map_free(struct rcu_head *rcu)
+{
+ struct kvm_apic_map *map = container_of(rcu, struct kvm_apic_map, rcu);
+
+ kvfree(map);
+}
+
static void recalculate_apic_map(struct kvm *kvm)
{
struct kvm_apic_map *new, *old = NULL;
@@ -160,8 +167,8 @@ static void recalculate_apic_map(struct kvm *kvm)
if (kvm_apic_present(vcpu))
max_id = max(max_id, kvm_apic_id(vcpu->arch.apic));

- new = kzalloc(sizeof(struct kvm_apic_map) +
- sizeof(struct kvm_lapic *) * (max_id + 1), GFP_KERNEL);
+ new = kvm_kvzalloc(sizeof(struct kvm_apic_map) +
+ sizeof(struct kvm_lapic *) * ((u64)max_id + 1));

if (!new)
goto out;
@@ -206,7 +213,7 @@ out:
mutex_unlock(&kvm->arch.apic_map_lock);

if (old)
- kfree_rcu(old, rcu);
+ call_rcu(&old->rcu, kvm_apic_map_free);

kvm_make_scan_ioapic_request(kvm);
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5d4089dcb3eb..411f786950ab 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7914,7 +7914,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
kfree(kvm->arch.vpic);
kfree(kvm->arch.vioapic);
kvm_free_vcpus(kvm);
- kfree(rcu_dereference_check(kvm->arch.apic_map, 1));
+ kvfree(rcu_dereference_check(kvm->arch.apic_map, 1));
kvm_mmu_uninit_vm(kvm);
}

--
2.9.0