69 lines
2.3 KiB
Rust
69 lines
2.3 KiB
Rust
// Inline asm wrappers.
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//
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// Userspace-callable: rdtsc, cpuid, svm_supported
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// Ring-0 stubs: read_cr3, write_cr3, vmload, vmsave, vmrun, rdmsr, wrmsr
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// these are here for when this code runs in a kernel context
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// Calling them from userspace will #GP or #UD
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/// Read the hardware timestamp counter (TSC)
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/// Used for timing guest memory access patterns (cache-timing side channels)
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#[inline(always)]
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pub fn rdtsc() -> u64 {
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let lo: u32;
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let hi: u32;
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unsafe {
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core::arch::asm!(
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"rdtsc",
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out("eax") lo,
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out("edx") hi,
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options(nomem, nostack, preserves_flags),
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);
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}
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((hi as u64) << 32) | lo as u64
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}
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/// CPUID — leaf + subleaf, returns (eax, ebx, ecx, edx).
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/// rbx is LLVM-reserved so we save/restore it around the instruction.
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pub fn cpuid(leaf: u32, subleaf: u32) -> (u32, u32, u32, u32) {
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let (eax, ebx, ecx, edx): (u32, u32, u32, u32);
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unsafe {
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core::arch::asm!(
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"push rbx",
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"cpuid",
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"mov {ebx_out:e}, ebx",
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"pop rbx",
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inout("eax") leaf => eax,
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inout("ecx") subleaf => ecx,
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ebx_out = out(reg) ebx,
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out("edx") edx,
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options(nomem, nostack, preserves_flags),
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);
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}
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(eax, ebx, ecx, edx)
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}
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/// Possible delete only used to check for AMD SVM
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/// Check whether the host CPU supports AMD SVM (CPUID 0x80000001 ECX bit 2).
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pub fn svm_supported() -> bool {
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let (_, _, ecx, _) = cpuid(0x8000_0001, 0);
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ecx & (1 << 2) != 0
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}
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// All of these should fault at CPL > 0 (#GP or #UD).
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unsafe extern "C" {
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/// Read host CR3. Returns the physical address of the host PML4.
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pub fn read_cr3() -> u64;
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/// Write host CR3 — flushes all non-global TLB entries.
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pub fn write_cr3(cr3: u64);
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/// VMLOAD — loads guest state from the VMCB at the given physical address. AMD SVM.
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pub fn vmload(vmcb_pa: u64);
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/// VMSAVE — saves guest state back to the VMCB at the given physical address. AMD SVM.
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pub fn vmsave(vmcb_pa: u64);
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/// VMRUN — enters the guest. Does not return until a #VMEXIT occurs. AMD SVM.
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pub fn vmrun(vmcb_pa: u64);
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/// RDMSR — read model-specific register.
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pub fn rdmsr(msr: u32) -> u64;
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/// WRMSR — write model-specific register.
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pub fn wrmsr(msr: u32, val: u64);
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}
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