diff --git a/kvm/src/lib.rs b/kvm/src/lib.rs index 5f321f2487..2fdac4354d 100644 --- a/kvm/src/lib.rs +++ b/kvm/src/lib.rs @@ -1007,6 +1007,32 @@ impl Vcpu { Ok(()) } + /// Gets the VCPU extended control registers + #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] + pub fn get_xcrs(&self) -> Result { + // Safe because we know that our file is a VCPU fd, we know the kernel will only write the + // correct amount of memory to our pointer, and we verify the return result. + let mut regs = unsafe { std::mem::zeroed() }; + let ret = unsafe { ioctl_with_mut_ref(self, KVM_GET_XCRS(), &mut regs) }; + if ret != 0 { + return errno_result(); + } + Ok(regs) + } + + /// Sets the VCPU extended control registers + #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] + pub fn set_xcrs(&self, xcrs: &kvm_xcrs) -> Result<()> { + let ret = unsafe { + // Here we trust the kernel not to read past the end of the kvm_xcrs struct. + ioctl_with_ref(self, KVM_SET_XCRS(), xcrs) + }; + if ret < 0 { + return errno_result(); + } + Ok(()) + } + /// X86 specific call to get the MSRS /// /// See the documentation for KVM_SET_MSRS. @@ -1557,6 +1583,27 @@ mod tests { assert_eq!(dregs.dr7, dregs2.dr7); } + #[test] + #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] + fn xcrs() { + let kvm = Kvm::new().unwrap(); + if kvm.check_extension(Cap::Xcrs) { + return; + } + + let gm = GuestMemory::new(&vec![(GuestAddress(0), 0x10000)]).unwrap(); + let vm = Vm::new(&kvm, gm).unwrap(); + let vcpu = Vcpu::new(0, &kvm, &vm).unwrap(); + let mut xcrs = vcpu.get_xcrs().unwrap(); + xcrs.nr_xcrs = 1; + xcrs.flags = 0; + // We assume anything we run on has SSE (bit 1). FP bit (bit 0) must always be set. + xcrs.xcrs[0].value |= 3; + vcpu.set_xcrs(&xcrs).unwrap(); + let xcrs2 = vcpu.get_xcrs().unwrap(); + assert_eq!(xcrs.xcrs[0].value, xcrs2.xcrs[0].value); + } + #[test] #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] fn get_msrs() {