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authorAvi Kivity <avi@redhat.com>2009-09-01 12:03:25 +0300
committerAvi Kivity <avi@redhat.com>2009-09-10 18:11:10 +0300
commit0a79b009525b160081d75cef5dbf45817956acf2 (patch)
tree86dc2671cbd3326e92c8845ce699bdb651d785b5
parent4da748960a6bd7b1e123e01bfa8f2dbcb6be209e (diff)
KVM: VMX: Check cpl before emulating debug register access
Debug registers may only be accessed from cpl 0. Unfortunately, vmx will code to emulate the instruction even though it was issued from guest userspace, possibly leading to an unexpected trap later. Cc: stable@kernel.org Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
-rw-r--r--arch/x86/include/asm/kvm_host.h1
-rw-r--r--arch/x86/kvm/vmx.c2
-rw-r--r--arch/x86/kvm/x86.c13
3 files changed, 16 insertions, 0 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e8f166a..3be0004 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -620,6 +620,7 @@ void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr);
void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
void kvm_inject_page_fault(struct kvm_vcpu *vcpu, unsigned long cr2,
u32 error_code);
+bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl);
int kvm_pic_set_irq(void *opaque, int irq, int level);
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index cc6e00a..f381201 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2934,6 +2934,8 @@ static int handle_dr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
unsigned long val;
int dr, reg;
+ if (!kvm_require_cpl(vcpu, 0))
+ return 1;
dr = vmcs_readl(GUEST_DR7);
if (dr & DR7_GD) {
/*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7627ff6..4137cc5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -223,6 +223,19 @@ void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code)
EXPORT_SYMBOL_GPL(kvm_queue_exception_e);
/*
+ * Checks if cpl <= required_cpl; if true, return true. Otherwise queue
+ * a #GP and return false.
+ */
+bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl)
+{
+ if (kvm_x86_ops->get_cpl(vcpu) <= required_cpl)
+ return true;
+ kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
+ return false;
+}
+EXPORT_SYMBOL_GPL(kvm_require_cpl);
+
+/*
* Load the pae pdptrs. Return true is they are all valid.
*/
int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)