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Fix various bugs #20

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Merged
tylerfanelli merged 2 commits into from
Nov 24, 2025
Merged

Fix various bugs #20

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41672c2
tdvf: use `#[repr(C)]` on packed structs
jakecorrenti Nov 21, 2025
5e8d3e6
launch: support dynamically determining nr_cpuid
jakecorrenti Nov 21, 2025
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2 changes: 0 additions & 2 deletions src/launch/linux.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,6 @@

use std::marker::PhantomData;

pub const NR_CPUID_CONFIGS: usize = 24;

/// Trust Domain eXtensions sub-ioctl() commands
#[repr(u32)]
pub enum CmdId {
Expand Down
66 changes: 41 additions & 25 deletions src/launch/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ mod bindings;
mod linux;

use bindings::{kvm_tdx_capabilities, kvm_tdx_init_mem_region, kvm_tdx_init_vm};
use linux::{Cmd, CmdId, NR_CPUID_CONFIGS};
use linux::{Cmd, CmdId};

use bitflags::bitflags;
use iocuddle::*;
Expand Down Expand Up @@ -128,31 +128,47 @@ impl Launcher {
/// in the system.
pub fn get_capabilities(&mut self) -> Result<TdxCapabilities> {
let mut caps = kvm_tdx_capabilities::default();

let mut defaults = Vec::with_capacity(NR_CPUID_CONFIGS);
(0..NR_CPUID_CONFIGS)
.for_each(|_| defaults.push(kvm_bindings::kvm_cpuid_entry2::default()));
let mut cpuid_entries = vec_with_array_field::<
kvm_tdx_capabilities,
kvm_bindings::kvm_cpuid_entry2,
>(NR_CPUID_CONFIGS);
cpuid_entries[0].cpuid.nent = NR_CPUID_CONFIGS as u32;
cpuid_entries[0].cpuid.padding = 0;
unsafe {
let cpuid_entries_slice: &mut [kvm_bindings::kvm_cpuid_entry2] = cpuid_entries[0]
.cpuid
.entries
.as_mut_slice(NR_CPUID_CONFIGS);
cpuid_entries_slice.copy_from_slice(defaults.as_slice());
let mut defaults: Vec<kvm_bindings::kvm_cpuid_entry2>;
let mut cpuid_entries: Vec<kvm_tdx_capabilities>;

let mut nr_cpuid_configs = 6;

loop {
// configure the vec of the defaults with a nr_cpuid_configs capacity
defaults = Vec::with_capacity(nr_cpuid_configs);
(0..nr_cpuid_configs)
.for_each(|_| defaults.push(kvm_bindings::kvm_cpuid_entry2::default()));

// allocate the memory for the dynamic number of entries to be eventually copied into
cpuid_entries = vec_with_array_field::<
kvm_tdx_capabilities,
kvm_bindings::kvm_cpuid_entry2,
>(nr_cpuid_configs);
cpuid_entries[0].cpuid.nent = nr_cpuid_configs as u32;
cpuid_entries[0].cpuid.padding = 0;
unsafe {
let cpuid_entries_slice: &mut [kvm_bindings::kvm_cpuid_entry2] = cpuid_entries[0]
.cpuid
.entries
.as_mut_slice(nr_cpuid_configs);
cpuid_entries_slice.copy_from_slice(defaults.as_slice());
}
caps.cpuid.nent = nr_cpuid_configs as u32;
caps.cpuid.padding = 0;
let mut cmd: Cmd<kvm_tdx_capabilities> =
Cmd::from(CmdId::GetCapabilities, &cpuid_entries[0]);

match GET_CAPABILITIES.ioctl(&mut self.vm_fd, &mut cmd) {
Err(e) if e.raw_os_error().is_some_and(|x| x == 7) => {
drop(defaults);
drop(cpuid_entries);
nr_cpuid_configs *= 2;
continue;
}
Err(e) => return Err(Error::GetCapabilities(e)),
Ok(_) => break,
};
}
caps.cpuid.nent = NR_CPUID_CONFIGS as u32;
caps.cpuid.padding = 0;
let mut cmd: Cmd<kvm_tdx_capabilities> =
Cmd::from(CmdId::GetCapabilities, &cpuid_entries[0]);

GET_CAPABILITIES
.ioctl(&mut self.vm_fd, &mut cmd)
.map_err(Error::GetCapabilities)?;

Ok(TdxCapabilities {
attributes: AttributesFlags::from_bits_truncate(cpuid_entries[0].supported_attrs),
Expand Down
4 changes: 2 additions & 2 deletions src/tdvf/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ use uuid::Uuid;
const EXPECTED_TABLE_FOOTER_GUID: &str = "96b582de-1fb2-45f7-baea-a366c55a082d";
const EXPECTED_METADATA_GUID: &str = "e47a6535-984a-4798-865e-4685a7bf8ec2";

#[repr(packed)]
#[repr(C, packed)]
#[derive(Default, Debug)]
struct TdvfDescriptor {
/// Signature should equal "TDVF" in bytes
Expand All @@ -24,7 +24,7 @@ struct TdvfDescriptor {
number_of_section_entry: u32,
}

#[repr(packed)]
#[repr(C, packed)]
#[derive(Clone, Copy, Default, Debug)]
pub struct TdvfSection {
/// The offset to the raw section in the binary image
Expand Down