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kvm: plumb accessor for KVM_GET_MSR_INDEX_LIST

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Plumb in KVM_GET_MSR_INDEX_LIST to allow clients to figure out what MSRs
are supported.

BUG=b:111083877
TEST=cargo test -p kvm

Change-Id: I69deba32a21fb9360f8cd53001d717338523fb71
Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1152228
Reviewed-by: Zach Reizner <zachr@chromium.org>
This commit is contained in:
Dmitry Torokhov 2018-07-26 13:48:56 -07:00 committed by chrome-bot
parent 0ed91abecd
commit c017a764d7
1 changed files with 47 additions and 0 deletions
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47
kvm/src/lib.rs
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@ -160,6 +160,45 @@ impl Kvm {
pub fn get_emulated_cpuid(&self) -> Result<CpuId> {
self.get_cpuid(KVM_GET_EMULATED_CPUID())
}
/// X86 specific call to get list of supported MSRS
///
/// See the documentation for KVM_GET_MSR_INDEX_LIST.
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
pub fn get_msr_index_list(&self) -> Result<Vec<u32>> {
const MAX_KVM_MSR_ENTRIES: usize = 256;
let vec_size_bytes = size_of::<kvm_msr_list>() +
MAX_KVM_MSR_ENTRIES * size_of::<u32>();
let bytes: Vec<u8> = vec![0; vec_size_bytes];
let msr_list: &mut kvm_msr_list = unsafe {
// We have ensured in new that there is enough space for the structure so this
// conversion is safe.
&mut *(bytes.as_ptr() as *mut kvm_msr_list)
};
msr_list.nmsrs = MAX_KVM_MSR_ENTRIES as u32;
let ret = unsafe {
// ioctl is unsafe. The kernel is trusted not to write beyond the bounds of the memory
// allocated for the struct. The limit is read from nmsrs, which is set to the allocated
// size (MAX_KVM_MSR_ENTRIES) above.
ioctl_with_mut_ref(self, KVM_GET_MSR_INDEX_LIST(), msr_list)
};
if ret < 0 {
return errno_result();
}
// Mapping the unsized array to a slice is unsafe because the length isn't known. Using
// the length we originally allocated with eliminates the possibility of overflow.
let indices: &[u32] = unsafe {
if msr_list.nmsrs > MAX_KVM_MSR_ENTRIES as u32 {
msr_list.nmsrs = MAX_KVM_MSR_ENTRIES as u32;
}
msr_list.indices.as_slice(msr_list.nmsrs as usize)
};
Ok(indices.to_vec())
}
}
impl AsRawFd for Kvm {
@ -1391,6 +1430,14 @@ mod tests {
kvm.get_emulated_cpuid().unwrap();
}
#[test]
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
fn get_msr_index_list() {
let kvm = Kvm::new().unwrap();
let msr_list = kvm.get_msr_index_list().unwrap();
assert!(msr_list.len() >= 2);
}
#[test]
fn add_memory() {
let kvm = Kvm::new().unwrap();