KVM: x86 emulator: Fix task switch privilege checks

Currently, all task switches check privileges against the DPL of the
TSS. This is only correct for jmp/call to a TSS. If a task gate is used,
the DPL of this take gate is used for the check instead. Exceptions,
external interrupts and iret shouldn't perform any check.

[avi: kill kvm-kmod remnants]

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 0b7690ee20b..95cdeaf9c71 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2799,7 +2799,10 @@ static int task_switch_interception(struct vcpu_svm *svm)
              (int_vec == OF_VECTOR || int_vec == BP_VECTOR)))
                 skip_emulated_instruction(&svm->vcpu);
 
-        if (kvm_task_switch(&svm->vcpu, tss_selector, reason,
+        if (int_type != SVM_EXITINTINFO_TYPE_SOFT)
+                int_vec = -1;
+
+        if (kvm_task_switch(&svm->vcpu, tss_selector, int_vec, reason,
                                 has_error_code, error_code) == EMULATE_FAIL) {
                 svm->vcpu.run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
                 svm->vcpu.run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;