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| author | Avi Kivity <avi@redhat.com> | 2009-09-01 12:03:25 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-04-01 15:52:24 -0700 |
| commit | 0a32cd3d6adbe5cbfdfb411e1b1fccceec75e36a (patch) | |
| tree | bde11ebee14af04c388cc6b3e06612e46eb504d3 | |
| parent | a3edfd184017a67b30080c1e0d46b91d7306b3d9 (diff) | |
| download | lwn-0a32cd3d6adbe5cbfdfb411e1b1fccceec75e36a.tar.gz lwn-0a32cd3d6adbe5cbfdfb411e1b1fccceec75e36a.zip | |
KVM: VMX: Check cpl before emulating debug register access
commit 0a79b009525b160081d75cef5dbf45817956acf2 upstream.
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.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | arch/x86/kvm/vmx.c | 3 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 13 | ||||
| -rw-r--r-- | include/asm-x86/kvm_host.h | 1 |
3 files changed, 17 insertions, 0 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 4cee61a464e4..7981dbe4eecb 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2464,6 +2464,9 @@ 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; + /* * FIXME: this code assumes the host is debugging the guest. * need to deal with guest debugging itself too. diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index bf872f272890..994722494215 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -198,6 +198,19 @@ static void __queue_exception(struct kvm_vcpu *vcpu) } /* + * 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) diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h index cf7c887165c4..69d4de9b2bbc 100644 --- a/include/asm-x86/kvm_host.h +++ b/include/asm-x86/kvm_host.h @@ -537,6 +537,7 @@ 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); void kvm_inject_nmi(struct kvm_vcpu *vcpu); |