[Xen-devel] how to set VM into debug mode ? what are xmx_entry_helper for?

[yandong han <toyandong@xxxxxxxxx>]

hi,all

I have three problems,anyone can solve them or one of them or give me some clue? thank you

(1)  first, I want to know what job  xmx_entry_helper   does?

(2) second , whether every VMENTRY will call xmx_entry_helper   ?if not, which function  will VMENTRY call  everytime?

(3)my target is setting VM into debug mode  by set Trag_flag,  the code below  called vmx_properly_set_trap_flag, 

and I add it at the end of vmx_vmexit_handler(). but it does not work.

 inline void vmx_properly_set_trap_flag(struct vcpu *v)

1301 {

1302     /* we are currently stepping, so we need to set the trap flag

1303     * on the next instruction

1304     */

1305     unsigned long int_state = __vmread(GUEST_INTERRUPTIBILITY_INFO);

1306     unsigned long activity_state = __vmread(GUEST_ACTIVITY_STATE);

1307

1308     unsigned long intercepts = __vmread(EXCEPTION_BITMAP);

1309     unsigned long mask = (1UL << TRAP_debug );

1310

1311     unsigned long flags = __vmread(GUEST_RFLAGS);

1312     unsigned long flags_mask = (X86_EFLAGS_TF);

1313

1314     /* make sure the exception bitmap says to vmexit on

1315      * debug exceptions

1316      */

1317     intercepts |= mask;

1318     __vmwrite(EXCEPTION_BITMAP, intercepts);

1319

1320     /* Default to setting trap flag to on */

1321     flags |= flags_mask;

1322

1323     if((activity_state == 1))

1324     {

1325

1326         /* this means we're in HLT mode. Disabling is OK since

1327         ** we will get an NMI to get out of HLT.

1328         ** The NMI will cause a VMExit which will reset TF

1329         ** execution

1330         **/

1331         printk("Turning off SS due to HLT\n");

1332         //flags &= ~(flags_mask);

1333     }

1334

1335     if((int_state & 3) )

1336     {

1337         int_state &= ~(3);

1338         printk("init_state is 3\n");

1339         //__vmwrite(GUEST_INTERRUPTIBILITY_INFO, int_state);

1340     }

1342     /* setting TF due to stepping enabled;*/

1343     __vmwrite(GUEST_RFLAGS, flags);

1344

1345 }

thank you , hope for your help 

--

----------------------------------------------------------
regards,

yandong

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