updated 02-KVM.md

course/02-KVM.md

@@ -856,16 +856,6 @@ if (!run->mmio.is_write) {  // See struct kvm_run
 [//]: # ----------------------------------------------------------------
 # Device emulation
 
-[//]: # ----------------------------------------------------------------
-## Reminder: MMIO registers
-
-When the VM is created:
-
-- The VMM constructs the VM address space by:
-  - mapping the RAM into the VM address space
-  - if the VM exposes some device programmed through MMIO registers, it must ensure there is no memory mapping (RAM) where device registers are located:
-    - ensure `VMexits` (`KVM_EXIT_MMIO`) will be triggered when OS driver code read/write to these addresses (registers)
-
 [//]: # ----------------------------------------------------------------
 ## Reminder: VMexits
 
@@ -914,8 +904,8 @@ outb(0x3C5, 0x0F);
 \footnotesize
 - The code above would typically be part of the VGA driver in the guest OS
 - How can the VMM emulate the behavior of a real PC running this code?
-  - \footnotesize by analyzing the code ran by the guest OS
-  - if the VMM detects the exact code above, it then emulates the behavior on the host
+  - \footnotesize by analyzing the sequence of VMExits triggered by the guest OS
+  - if the VMM detects the exact sequence of I/O registers reads/writes above, it then emulates the behavior on the host
   - for instance by opening a 400x300 pixels window in which pixels will be rendered
 
 [//]: # ----------------------------------------------------------------
@@ -947,10 +937,10 @@ outb(0x3C5, 0x0F);
 [//]: # ----------------------------------------------------------------
 ## Generic state machine representation (1/2)
 
-Represent each state by a structure that defines:
+**\textcolor{myblue}{Idea}**: to represent each state by a structure that defines:
 
 - the operation to perform
-- the written/read address
+- the address written to/read from
 - the expected written value or value to inject
 - the size of the operation (8, 16, or 32 bits)
 - possibly a custom user function that would be executed at the beginning or end of the state