Update README.md

merge-requests/1/head
_xeroxz 4 years ago
parent 76debbfcb5
commit 7e6fdcc86b

@ -120,4 +120,22 @@ vcpu->tss.interrupt_stack_table[idt::ist_idx::de] =
PAGE_SIZE * HOST_STACK_PAGES)) + (PAGE_SIZE * HOST_STACK_PAGES);
```
#### IDT - Interrupt Descriptor Table
#### IDT - Interrupt Descriptor Table
The host IDT is 1:1 to the guest IDT except for three interrupt handlers, #PF, #DE, and #GP. These three different interrupt handlers all route to the same SEH handler function
which just changes RIP to the catch block of whatever try/except the exception happened in. This allows for page faults, general protection faults and division errors to not be handled
by guest controlled interrupt handlers.
```cpp
// setup IDT for host....
segment_descriptor_register_64 idt_value;
__sidt(&idt_value);
// copy the guest IDT entries...
memcpy(idt::table, (void*)idt_value.base_address, idt_value.limit);
// change gp, pf, and de to vmxroot handlers...
idt::table[general_protection] = idt::create_entry(hv::idt_addr_t{ __gp_handler }, idt::ist_idx::gp);
idt::table[page_fault] = idt::create_entry(hv::idt_addr_t{ __pf_handler }, idt::ist_idx::pf);
idt::table[divide_error] = idt::create_entry(hv::idt_addr_t{ __de_handler }, idt::ist_idx::de);
```

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