ioctls/vcpu: Introduce hvcall_ version of set/get vp registers

Signed-off-by: Nuno Das Neves <nudasnev@microsoft.com>

mshv-ioctls/src/ioctls/vcpu.rs

@@ -80,12 +80,45 @@ impl VcpuFd {
         }
         Ok(())
     }
-    /// Sets a vCPU register to input value.
-    ///
-    /// # Arguments
-    ///
-    /// * `reg_name` - general purpose register name.
-    /// * `reg_value` - register value.
+    /// Generic hvcall version of get_reg
+    pub fn hvcall_get_reg(&self, reg_assocs: &mut [hv_register_assoc]) -> Result<()> {
+        if reg_assocs.is_empty() {
+            return Err(libc::EINVAL.into());
+        }
+        let reg_names: Vec<hv_register_name> = reg_assocs.iter().map(|assoc| assoc.name).collect();
+        let input = make_rep_input!(
+            hv_input_get_vp_registers {
+                vp_index: self.index,
+                ..Default::default()
+            },
+            names,
+            reg_names.as_slice()
+        );
+        let mut output: Vec<hv_register_value> = reg_names
+            .iter()
+            .map(|_| hv_register_value {
+                reg128: hv_u128 {
+                    ..Default::default()
+                },
+            })
+            .collect();
+        let output_slice = output.as_mut_slice();
+
+        let mut args = make_rep_args!(HVCALL_GET_VP_REGISTERS, input, output_slice);
+        self.hvcall(&mut args)?;
+
+        if args.reps as usize != reg_assocs.len() {
+            // TODO better handling? partial success?
+            return Err(libc::EINTR.into());
+        }
+
+        for (assoc, value) in reg_assocs.iter_mut().zip(output.iter()) {
+            assoc.value = *value;
+        }
+
+        Ok(())
+    }
+    /// Set vcpu register values by providing an array of register assocs
     #[cfg(not(target_arch = "aarch64"))]
     pub fn set_reg(&self, regs: &[hv_register_assoc]) -> Result<()> {
         let hv_vp_register_args = mshv_vp_registers {
@@ -97,6 +130,27 @@ impl VcpuFd {
         if ret != 0 {
             return Err(MshvError::from_last_errno());
         }
+
+        Ok(())
+    }
+    /// Generic hypercall version of set_reg
+    pub fn hvcall_set_reg(&self, reg_assocs: &[hv_register_assoc]) -> Result<()> {
+        let input = make_rep_input!(
+            hv_input_set_vp_registers {
+                vp_index: self.index,
+                ..Default::default()
+            },
+            elements,
+            reg_assocs
+        );
+        let mut args = make_rep_args!(HVCALL_SET_VP_REGISTERS, input);
+        self.hvcall(&mut args)?;
+
+        if args.reps as usize != reg_assocs.len() {
+            // TODO better handling? partial success?
+            return Err(libc::EINTR.into());
+        }
+
         Ok(())
     }
     /// Sets the vCPU general purpose registers