[patch 2/3] KVM: task switch: check task busy state

[Marcelo Tosatti]

Checks that the new task is available (call, jump, exception, or interrupt) or 
busy (IRET return). Generate GP# or TS# otherwise.

Signed-off-by: Marcelo Tosatti <[EMAIL PROTECTED]>

Index: kvm-vmx-checks/arch/x86/kvm/x86.c
===================================================================
--- kvm-vmx-checks.orig/arch/x86/kvm/x86.c
+++ kvm-vmx-checks/arch/x86/kvm/x86.c
@@ -3519,6 +3519,11 @@ int kvm_task_switch(struct kvm_vcpu *vcp
        if (load_guest_segment_descriptor(vcpu, old_tss_sel, &cseg_desc))
                goto out;
 
+       if (!nseg_desc.p || (nseg_desc.limit0 | nseg_desc.limit << 16) < 0x67) {
+               kvm_queue_exception_e(vcpu, TS_VECTOR, tss_selector & 0xfffc);
+               return 1;
+       }
+
        if (reason != TASK_SWITCH_IRET) {
                int cpl;
 
@@ -3527,12 +3532,19 @@ int kvm_task_switch(struct kvm_vcpu *vcp
                        kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
                        return 1;
                }
+               if (nseg_desc.type & (1 << 1)) {
+                       kvm_queue_exception_e(vcpu, GP_VECTOR,
+                                             old_tss_sel & 0xfffc);
+                       return 1;
+               }
+       } else {
+               if (!(cseg_desc.type & (1 << 1))) {
+                       kvm_queue_exception_e(vcpu, TS_VECTOR,
+                                             tss_selector & 0xfffc);
+                       return 1;
+               }
        }
 
-       if (!nseg_desc.p || (nseg_desc.limit0 | nseg_desc.limit << 16) < 0x67) {
-               kvm_queue_exception_e(vcpu, TS_VECTOR, tss_selector & 0xfffc);
-               return 1;
-       }
 
        if (reason == TASK_SWITCH_IRET || reason == TASK_SWITCH_JMP) {
                cseg_desc.type &= ~(1 << 1); //clear the B flag

-- 

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