Description of interrupts module in x86_64 #14

anirudhakulkarni · 2022-09-12T10:24:43Z

vmm-reference-interrupts.md

its-sachin · 2022-09-12T17:29:25Z

vmm-reference-interrupts.md

@@ -0,0 +1,116 @@
+# Interrupts (x86_64 architecture)
+* source file: vmm-reference/src/vm-vcpu/src/x86_64/interrupts.rs 
+* Note: This document only covers the x86_64 architecture. For aarch64, the interrupt controller is called GIC (Generic Interrupt Controller). Refer to vmm-reference/src/vm-vcpu/src/aarch64/interrupts.rs


vmm-reference-interrupts.md

anirudhakulkarni · 2022-09-17T12:04:04Z

@arch1902 @Intact01 updated. Kindly review

SatyamModi

Looks good to me.

codenet

Decent PR. Well done!

codenet · 2022-09-20T08:09:03Z

vmm-reference-interrupts.md

+* source file: vmm-reference/src/vm-vcpu-ref/src/x86_64/interrupts.rs 
+* Note: This document only covers the x86_64 architecture. For aarch64, the interrupt controller is called GIC (Generic Interrupt Controller). Refer to vmm-reference/src/vm-vcpu-ref/src/aarch64/interrupts.rs
+## Local Advanced Programmable Interrupt Controller (LAPIC)
+LAPIC is a memory-mapped device that is used to send interrupts to the VCPUs. It is used to send interrupts to the VCPUs and to receive interrupts from the VCPUs. It is also used to send inter-processor interrupts (IPIs) to the VCPUs.


Redundant first two sentences. You can change to :

LAPIC is a memory-mapped device that is used to send/receive interrupts to/from the VCPUs.

codenet · 2022-09-20T08:10:00Z

vmm-reference-interrupts.md

+## Local Advanced Programmable Interrupt Controller (LAPIC)
+LAPIC is a memory-mapped device that is used to send interrupts to the VCPUs. It is used to send interrupts to the VCPUs and to receive interrupts from the VCPUs. It is also used to send inter-processor interrupts (IPIs) to the VCPUs.
+
+There are five delivery modes for interrupts:


It will be good to know the source of this information. Example "According to the Section xyz from Intel Manual volume abc".

codenet · 2022-09-20T08:12:59Z

vmm-reference-interrupts.md

+
+## Usage in code
+
+While creating a new ```kvmVcpu```, LAPICs for the vcpu is created and initialized with ```configure_lapic``` function. The function ```configure_lapic``` initializes the LAPICs with the following values: 


which file exactly is this in?

codenet · 2022-09-20T08:14:09Z

vmm-reference-interrupts.md

+```rust
+    fn configure_lapic(&self) -> Result<()> {
+        let mut klapic: kvm_lapic_state = self.vcpu_fd.get_lapic().map_err(Error::KvmIoctl)?;
+        set_klapic_delivery_mode(&mut klapic, APIC_LVT0_REG_OFFSET, DeliveryMode::ExtINT).unwrap();
+        set_klapic_delivery_mode(&mut klapic, APIC_LVT1_REG_OFFSET, DeliveryMode::NMI).unwrap();
+        self.vcpu_fd.set_lapic(&klapic).map_err(Error::KvmIoctl)
+    }
+```


This could be moved to the markdown file that explains the parent rust file that holds configure_lapic. configure_lapic explanation in the other file can keep a pointer to this file to know more about LAPICs.

codenet · 2022-09-20T08:15:12Z

vmm-reference-interrupts.md

+        self.vcpu_fd.set_lapic(&klapic).map_err(Error::KvmIoctl)
+    }
+```
+Here `APIC_LVT0_REG_OFFSET` is the register offset corresponding to the APIC Local Vector Table for LINT0 and set to `0x350` and `APIC_LVT1_REG_OFFSET` is the register offset corresponding to the APIC Local Vector Table for LINT1 and set to `0x360`.


What is the significance of 0x350 and 0x360?

Create vmm-reference-interrupts.md

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anirudhakulkarni mentioned this pull request Sep 12, 2022

Description of the interrupts module codenet/vmm-reference#3

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anirudhakulkarni changed the title ~~Create vmm-reference-interrupts.md~~ Description of interrupts module in x86_64 Sep 12, 2022

arch1902 reviewed Sep 12, 2022

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