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From 5b40572ed5f0344b9dbee486a17c589ce1abe1a3 Mon Sep 17 00:00:00 2001
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From: Avi Kivity <avi@redhat.com>
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Date: Mon, 5 Mar 2012 14:23:29 +0200
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Subject: [PATCH] KVM: Ensure all vcpus are consistent with in-kernel irqchip
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settings
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If some vcpus are created before KVM_CREATE_IRQCHIP, then
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irqchip_in_kernel() and vcpu->arch.apic will be inconsistent, leading
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to potential NULL pointer dereferences.
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Fix by:
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- ensuring that no vcpus are installed when KVM_CREATE_IRQCHIP is called
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- ensuring that a vcpu has an apic if it is installed after KVM_CREATE_IRQCHIP
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This is somewhat long winded because vcpu->arch.apic is created without
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kvm->lock held.
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Based on earlier patch by Michael Ellerman.
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Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
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Signed-off-by: Avi Kivity <avi@redhat.com>
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---
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arch/ia64/kvm/kvm-ia64.c | 5 +++++
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arch/x86/kvm/x86.c | 8 ++++++++
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include/linux/kvm_host.h | 7 +++++++
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virt/kvm/kvm_main.c | 4 ++++
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4 files changed, 24 insertions(+), 0 deletions(-)
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diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
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index d8ddbba..f5104b7 100644
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--- a/arch/ia64/kvm/kvm-ia64.c
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+++ b/arch/ia64/kvm/kvm-ia64.c
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@@ -1172,6 +1172,11 @@ out:
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#define PALE_RESET_ENTRY 0x80000000ffffffb0UL
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+bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu)
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+{
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+ return irqchip_in_kernel(vcpu->kcm) == (vcpu->arch.apic != NULL);
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+}
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+
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int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
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{
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struct kvm_vcpu *v;
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diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
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index 3ee008f..be9594a 100644
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--- a/arch/x86/kvm/x86.c
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+++ b/arch/x86/kvm/x86.c
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@@ -3199,6 +3199,9 @@ long kvm_arch_vm_ioctl(struct file *filp,
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r = -EEXIST;
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if (kvm->arch.vpic)
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goto create_irqchip_unlock;
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+ r = -EINVAL;
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+ if (atomic_read(&kvm->online_vcpus))
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+ goto create_irqchip_unlock;
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r = -ENOMEM;
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vpic = kvm_create_pic(kvm);
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if (vpic) {
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@@ -6107,6 +6110,11 @@ void kvm_arch_check_processor_compat(void *rtn)
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kvm_x86_ops->check_processor_compatibility(rtn);
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}
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+bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu)
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+{
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+ return irqchip_in_kernel(vcpu->kvm) == (vcpu->arch.apic != NULL);
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+}
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+
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int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
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{
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struct page *page;
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diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
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index 355e445..759fa26 100644
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--- a/include/linux/kvm_host.h
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+++ b/include/linux/kvm_host.h
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@@ -805,6 +805,13 @@ static inline bool kvm_vcpu_is_bsp(struct kvm_vcpu *vcpu)
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{
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return vcpu->kvm->bsp_vcpu_id == vcpu->vcpu_id;
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}
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+
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+bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu);
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+
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+#else
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+
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+static bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu) { return true; }
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+
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#endif
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#ifdef __KVM_HAVE_DEVICE_ASSIGNMENT
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diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
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index e4431ad..94e148e 100644
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--- a/virt/kvm/kvm_main.c
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+++ b/virt/kvm/kvm_main.c
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@@ -1651,6 +1651,10 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
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goto vcpu_destroy;
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mutex_lock(&kvm->lock);
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+ if (!kvm_vcpu_compatible(vcpu)) {
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+ r = -EINVAL;
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+ goto unlock_vcpu_destroy;
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+ }
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if (atomic_read(&kvm->online_vcpus) == KVM_MAX_VCPUS) {
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r = -EINVAL;
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goto unlock_vcpu_destroy;
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--
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1.7.7.6
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