linux-kernel - [PATCH v2 13/13] KVM: x86: bump KVM_MAX_VCPU

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Date:	Thu,  7 Jul 2016 19:15:50 +0200
From:	Radim Krčmář <rkrcmar@...hat.com>
To:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:	Paolo Bonzini <pbonzini@...hat.com>,
	"Lan, Tianyu" <tianyu.lan@...el.com>,
	Igor Mammedov <imammedo@...hat.com>,
	Jan Kiszka <jan.kiszka@....de>, Peter Xu <peterx@...hat.com>
Subject: [PATCH v2 13/13] KVM: x86: bump KVM_MAX_VCPU_ID to 1023

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@...hat.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