diff options
| -rw-r--r-- | README.md | 14 | ||||
| -rw-r--r-- | examples/long_mode.rs | 177 | ||||
| -rw-r--r-- | guest/Makefile | 13 | ||||
| -rw-r--r-- | guest/guest64.S | 17 |
4 files changed, 219 insertions, 2 deletions
@@ -15,6 +15,8 @@ The sources are structured as follows: ## Real Mode (16bit) example +Runs the [real mode VM](./examples/real_mode.rs) with the [guest program](./guest/guest16.S). + ```bash # Once: Build the guest binary image. make -C guest @@ -23,5 +25,17 @@ make -C guest cargo run --example real_mode ``` +## Long Mode (64bit) example + +Runs the [long mode VM](./examples/long_mode.rs) with the [guest program](./guest/guest64.S). + +```bash +# Once: Build the guest binary image. +make -C guest + +# Run the Long Mode example. +cargo run --example long_mode +``` + ## License This project is licensed under the [MIT](LICENSE) license. diff --git a/examples/long_mode.rs b/examples/long_mode.rs new file mode 100644 index 0000000..c926e79 --- /dev/null +++ b/examples/long_mode.rs @@ -0,0 +1,177 @@ +use kvm_rs::kvm::Kvm; +use kvm_rs::kvm_sys; +use kvm_rs::vcpu::KvmExit; +use kvm_rs::x86_64::*; +use kvm_rs::{PhysAddr, UserMem}; + +fn setup_long_mode_segments(sregs: &mut kvm_sys::kvm_sregs) { + let code_seg = |seg: &mut kvm_sys::kvm_segment| { + seg.base = 0x0; + // Limit (unused in 64bit). + seg.limit = 0x0; + // Segment selector -> Index=1, Table=GDT, RPL=0. + seg.selector = 0x8; + // Code read + execute. + seg.type_ = 10; + // Segment present. + seg.present = 1; + // Descriptor privilege level. + seg.dpl = 0; + // Operand/Pointer size (unused in 64bit, but must be 0 in 64bit mode). + seg.db = 0; + // Code/data segment. + seg.s = 1; + // Native 64 bit code segment. + seg.l = 1; + // Granularity (unused in 64bit). + seg.g = 0; + }; + + let data_seg = |seg: &mut kvm_sys::kvm_segment| { + seg.base = 0x0; + // Limit (unused in 64bit). + seg.limit = 0x0; + // Segment selector -> Index=2, Table=GDT, RPL=0. + seg.selector = 0x10; + // Data read + write. + seg.type_ = 2; + // Segment present. + seg.present = 1; + // Descriptor privilege level. + seg.dpl = 0; + // Operand/Pointer size (unused in 64bit, but must be 0 in 64bit mode). + seg.db = 0; + // Code/data segment. + seg.s = 1; + // Native 64 bit code segment. + seg.l = 0; + // Granularity (unused in 64bit). + seg.g = 0; + }; + + code_seg(&mut sregs.cs); + data_seg(&mut sregs.ds); + data_seg(&mut sregs.ss); + data_seg(&mut sregs.fs); + data_seg(&mut sregs.gs); + data_seg(&mut sregs.es); +} + +fn setup_long_mode_4level_paging(mem: &mut UserMem) -> PhysAddr { + assert_eq!(0x8000, mem.as_ref().len()); + + // As a small exercise we create the following 4-level virtual address mapping using 4K pages: + // VirtAddr [0x0000:0x3fff] -> PhysAddr [0x4000:0x7fff] + // + // The required paging structures we'll place at physical address [0x0000:0x3ffff]. + // + // PhysAddr + // +-------+ + // 0x0000 | PML4 | + // 0x1000 | PDP | + // 0x2000 | PD | + // 0x3000 | PT | VirtAddr + // 0x4000 +-------+ <----- +-------+ 0x0000 + // | Guest | | Guest | + // | (16K) | | (16K) | + // 0x8000 +-------+ <----- +-------+ 0x4000 + // + // PML4 : Pamge Map Level 4 + // PDP : Page Directory Pointer + // PD : Page Directory + // PT : Page Table + // + // PML4, PDP, PD will contain a single entry at index 0. + // PT will contain 4 page table entries (PTE) at index {0,1,2,3} -> 4 * 4K = 16K. + + let mut w = |addr: PhysAddr, val: u64| { + let addr = addr.0 as usize; + mem.as_mut()[addr..addr + 8].copy_from_slice(&val.to_le_bytes()); + }; + + // PML4E[0] refers to PDPE[0:4095]. + w(PhysAddr(0x0000), PAGE_ENTRY_PRESENT | PAGE_RENTRY_RW | 0x1000); + // PDPE[0] refers to PDE[0:4095]. + w(PhysAddr(0x1000), PAGE_ENTRY_PRESENT | PAGE_RENTRY_RW | 0x2000); + // PDE[0] refers to PTE[0:4095]. + w(PhysAddr(0x2000), PAGE_ENTRY_PRESENT | PAGE_RENTRY_RW | 0x3000); + + // PTE[0] maps Virt [0x0000:0x0fff] -> Phys [0x4000:0x4fff]. + w(PhysAddr(0x3000), PAGE_ENTRY_PRESENT | PAGE_RENTRY_RW | 0x4000); + // PTE[1] maps Virt [0x1000:0x1fff] -> Phys [0x5000:0x5fff]. + w(PhysAddr(0x3008), PAGE_ENTRY_PRESENT | PAGE_RENTRY_RW | 0x5000); + // PTE[2] maps Virt [0x2000:0x2fff] -> Phys [0x6000:0x6fff]. + w(PhysAddr(0x3010), PAGE_ENTRY_PRESENT | PAGE_RENTRY_RW | 0x6000); + // PTE[3] maps Virt [0x3000:0x3fff] -> Phys [0x7000:0x7fff]. + w(PhysAddr(0x3018), PAGE_ENTRY_PRESENT | PAGE_RENTRY_RW | 0x7000); + + // Return address of PML4. + PhysAddr(0x0000) +} + +fn setup_long_mode(sregs: &mut kvm_sys::kvm_sregs, mem: &mut UserMem) { + // Setup segment descriptors for long mode. + setup_long_mode_segments(sregs); + + // Setup paging structures. + let pml4_base = setup_long_mode_4level_paging(mem); + // Setup physical address of first paging structure (PML4). + sregs.cr3 = pml4_base.0; + + // Enable paging (PG) and protection (PE). + sregs.cr0 = CR0_PG | CR0_PE; + // Enable physical address extension (PAE). + sregs.cr4 = CR4_PAE; + // Set long mode active (LMA) and long mode enabled (LME). + sregs.efer = EFER_LMA | EFER_LME; +} + +fn main() -> std::io::Result<()> { + // Create VM & VCPU. + let vm = Kvm::new()?.create_vm()?; + let vcpu = vm.create_vpcu(0)?; + + // Map memory for guest VM. + let mut mem = UserMem::new(0x8000)?; + unsafe { + vm.set_user_memory_region(PhysAddr(0x0), &mem)?; + } + + // Load guest image at physical address starting from 0x4000. + mem.load(PhysAddr(0x4000), include_bytes!("../guest/guest64")); + + // Initialize VPCU registers. + let mut regs = vcpu.get_regs()?; + // Set `rip` to 0 as we want to start executing from virtual address 0. + regs.rip = 0; + regs.rflags = 0x2; + vcpu.set_regs(regs)?; + + // Initialize VPCU special registers. + let mut sregs = vcpu.get_sregs()?; + // Setup long mode and paging to map: + // VirtAddr [0x0000:0x3fff] -> PhysAddr [0x4000:0x7fff] + setup_long_mode(&mut sregs, &mut mem); + vcpu.set_sregs(sregs)?; + + // Run VCPU until `hlt` instruction. + while let Ok(exit) = vcpu.run() { + match exit { + KvmExit::Halt => break, + KvmExit::IoOut(_port, data) => { + let s = std::str::from_utf8(data).unwrap(); + print!("{}", s); + } + KvmExit::MmioWrite(addr, data) => { + println!( + "MMIO_WRITE: addr={:#x} len={} data={:#x?}", + addr, + data.len(), + data + ); + } + }; + } + + Ok(()) +} diff --git a/guest/Makefile b/guest/Makefile index e3f1e1b..a2eea1b 100644 --- a/guest/Makefile +++ b/guest/Makefile @@ -1,8 +1,17 @@ +guest: guest16 guest64 +disasm: disasm16 disasm64 + guest16: guest.ld guest16.S $(CC) $(CFLAGS) -m16 -o $@ -nostdlib -ffreestanding -Wpedantic -Wall -Wextra -Werror -T guest.ld guest16.S -disasm: guest16 +guest64: guest.ld guest64.S + $(CC) $(CFLAGS) -m64 -o $@ -nostdlib -fPIC -ffreestanding -Wpedantic -Wall -Wextra -Werror -T guest.ld guest64.S + +disasm16: guest16 objdump -D -b binary -m i8086 -M intel $^ +disasm64: guest64 + objdump -D -b binary -m i386:x86-64 -M intel $^ + clean: - $(RM) guest16 + $(RM) guest16 guest64 diff --git a/guest/guest64.S b/guest/guest64.S new file mode 100644 index 0000000..1862749 --- /dev/null +++ b/guest/guest64.S @@ -0,0 +1,17 @@ +.intel_syntax noprefix + +.section .boot, "ax", @progbits + // Trigger `KVM_EXIT_IO:KVM_EXIT_IO_OUT` by writing string to output port. + mov rdx, 0x1000 // Output port. + lea rsi, [rip + msg] // Address of string. + mov rcx, [rip + msg_len] // Len of string. + rep outsb // Write ds:rsi to output port rdx. + + // Trigger `KVM_EXIT_HLT`. + hlt + +.section .rodata, "a", @progbits +msg: + .asciz "Hello from Long Mode!\n" +msg_len: + .byte .-msg |