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Date: Tue, 02 Oct 2012 00:52:42 +0200
From: Willy Tarreau <w@....eu>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Michael Ellerman <michael@...erman.id.au>,
Avi Kivity <avi@...hat.com>, Willy Tarreau <w@....eu>
Subject: [ 045/180] KVM: Ensure all vcpus are consistent with in-kernel irqchip settings
2.6.32-longterm review patch. If anyone has any objections, please let me know.
------------------
From: Avi Kivity <avi@...hat.com>
commit 3e515705a1f46beb1c942bb8043c16f8ac7b1e9e upstream
If some vcpus are created before KVM_CREATE_IRQCHIP, then
irqchip_in_kernel() and vcpu->arch.apic will be inconsistent, leading
to potential NULL pointer dereferences.
Fix by:
- ensuring that no vcpus are installed when KVM_CREATE_IRQCHIP is called
- ensuring that a vcpu has an apic if it is installed after KVM_CREATE_IRQCHIP
This is somewhat long winded because vcpu->arch.apic is created without
kvm->lock held.
Based on earlier patch by Michael Ellerman.
Signed-off-by: Michael Ellerman <michael@...erman.id.au>
Signed-off-by: Avi Kivity <avi@...hat.com>
[dannf: backported to Debian's 2.6.32]
Signed-off-by: Willy Tarreau <w@....eu>
---
arch/ia64/kvm/kvm-ia64.c | 5 +++++
arch/x86/kvm/x86.c | 8 ++++++++
include/linux/kvm_host.h | 7 +++++++
virt/kvm/kvm_main.c | 4 ++++
4 files changed, 24 insertions(+), 0 deletions(-)
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 2eb6365..416122b 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1185,6 +1185,11 @@ out:
#define PALE_RESET_ENTRY 0x80000000ffffffb0UL
+bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu)
+{
+ return irqchip_in_kernel(vcpu->kcm) == (vcpu->arch.apic != NULL);
+}
+
int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu *v;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5908461..271fddf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2280,6 +2280,9 @@ long kvm_arch_vm_ioctl(struct file *filp,
r = -EEXIST;
if (kvm->arch.vpic)
goto create_irqchip_unlock;
+ r = -EINVAL;
+ if (atomic_read(&kvm->online_vcpus))
+ goto create_irqchip_unlock;
r = -ENOMEM;
vpic = kvm_create_pic(kvm);
if (vpic) {
@@ -5027,6 +5030,11 @@ void kvm_arch_check_processor_compat(void *rtn)
kvm_x86_ops->check_processor_compatibility(rtn);
}
+bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu)
+{
+ return irqchip_in_kernel(vcpu->kvm) == (vcpu->arch.apic != NULL);
+}
+
int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
{
struct page *page;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c728a50..8bfed57 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -556,5 +556,12 @@ static inline bool kvm_vcpu_is_bsp(struct kvm_vcpu *vcpu)
{
return vcpu->kvm->bsp_vcpu_id == vcpu->vcpu_id;
}
+
+bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu);
+
+#else
+
+static inline bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu) { return true; }
+
#endif
#endif
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 311ec18..82b6fdc 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1857,6 +1857,10 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
return r;
mutex_lock(&kvm->lock);
+ if (!kvm_vcpu_compatible(vcpu)) {
+ r = -EINVAL;
+ goto vcpu_destroy;
+ }
if (atomic_read(&kvm->online_vcpus) == KVM_MAX_VCPUS) {
r = -EINVAL;
goto vcpu_destroy;
--
1.7.2.1.45.g54fbc
--
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