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Subject[PATCH 02/40] KVM: x86: raise TSS exception for NULL CS and SS segments
Date
From: Marcelo Tosatti <mtosatti@redhat.com>

Windows 2003 uses task switch to triple fault and reboot (the other
exception being reserved pdptrs bits).

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
arch/x86/kvm/x86.c | 11 +++++++++++
1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b503614..47fab87 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4411,6 +4411,15 @@ static int is_vm86_segment(struct kvm_vcpu *vcpu, int seg)
(kvm_get_rflags(vcpu) & X86_EFLAGS_VM);
}

+static void kvm_check_segment_descriptor(struct kvm_vcpu *vcpu, int seg,
+ u16 selector)
+{
+ /* NULL selector is not valid for CS and SS */
+ if (seg == VCPU_SREG_CS || seg == VCPU_SREG_SS)
+ if (!selector)
+ kvm_queue_exception_e(vcpu, TS_VECTOR, selector >> 3);
+}
+
int kvm_load_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
int type_bits, int seg)
{
@@ -4420,6 +4429,8 @@ int kvm_load_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
return kvm_load_realmode_segment(vcpu, selector, seg);
if (load_segment_descriptor_to_kvm_desct(vcpu, selector, &kvm_seg))
return 1;
+
+ kvm_check_segment_descriptor(vcpu, seg, selector);
kvm_seg.type |= type_bits;

if (seg != VCPU_SREG_SS && seg != VCPU_SREG_CS &&
--
1.6.5.3


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