diff --git a/libs/hyp/src/error.rs b/libs/hyp/src/error.rs
new file mode 100644
index 0000000..20a0cff
--- /dev/null
+++ b/libs/hyp/src/error.rs
@@ -0,0 +1,45 @@
+// Copyright 2023, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Error and Result types for hypervisor.
+
+use core::{fmt, result};
+
+/// Result type with hypervisor error.
+pub type Result<T> = result::Result<T, Error>;
+
+/// Hypervisor error.
+#[derive(Debug, Clone)]
+pub enum Error {
+    /// MMIO guard is not supported.
+    MmioGuardNotsupported,
+    /// Failed to invoke a certain HVC function.
+    HvcError(smccc::Error, u32),
+    /// The MMIO_GUARD granule used by the hypervisor is not supported.
+    UnsupportedMmioGuardGranule(usize),
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Self::MmioGuardNotsupported => write!(f, "MMIO guard is not supported"),
+            Self::HvcError(e, function_id) => {
+                write!(f, "Failed to invoke the HVC function with function ID {function_id}: {e}")
+            }
+            Self::UnsupportedMmioGuardGranule(g) => {
+                write!(f, "Unsupported MMIO guard granule: {g}")
+            }
+        }
+    }
+}
diff --git a/libs/hyp/src/hypervisor/common.rs b/libs/hyp/src/hypervisor/common.rs
index d1439db..550fb2e 100644
--- a/libs/hyp/src/hypervisor/common.rs
+++ b/libs/hyp/src/hypervisor/common.rs
@@ -14,23 +14,20 @@
 
 //! This module regroups some common traits shared by all the hypervisors.
 
-use smccc::Result;
+use crate::error::Result;
 
 /// Trait for the hypervisor.
 pub trait Hypervisor {
-    /// Returns MMIO guard granule size in bytes.
-    fn mmio_guard_granule(&self) -> Result<usize>;
-
-    /// Registers to use MMIO guard APIs.
+    /// Initializes the hypervisor by enrolling a MMIO guard and checking the memory granule size.
     /// By enrolling, all MMIO will be blocked unless allow-listed with `mmio_guard_map`.
     /// Protected VMs are auto-enrolled.
-    fn mmio_guard_enroll(&self) -> Result<()>;
+    fn mmio_guard_init(&self) -> Result<()>;
 
     /// Maps a memory address to the hypervisor MMIO guard.
-    fn mmio_guard_map(&self, ipa: u64) -> Result<()>;
+    fn mmio_guard_map(&self, addr: usize) -> Result<()>;
 
     /// Unmaps a memory address from the hypervisor MMIO guard.
-    fn mmio_guard_unmap(&self, ipa: u64) -> Result<()>;
+    fn mmio_guard_unmap(&self, addr: usize) -> Result<()>;
 
     /// Shares a region of memory with host, granting it read, write and execute permissions.
     /// The size of the region is equal to the memory protection granule returned by
diff --git a/libs/hyp/src/hypervisor/kvm.rs b/libs/hyp/src/hypervisor/kvm.rs
index cac9ba2..615c75a 100644
--- a/libs/hyp/src/hypervisor/kvm.rs
+++ b/libs/hyp/src/hypervisor/kvm.rs
@@ -15,7 +15,8 @@
 //! Wrappers around calls to the KVM hypervisor.
 
 use super::common::Hypervisor;
-use smccc::{checked_hvc64, checked_hvc64_expect_zero, Error, Result};
+use crate::error::{Error, Result};
+use crate::util::{page_address, SIZE_4KB};
 
 const ARM_SMCCC_KVM_FUNC_HYP_MEMINFO: u32 = 0xc6000002;
 const ARM_SMCCC_KVM_FUNC_MEM_SHARE: u32 = 0xc6000003;
@@ -29,46 +30,43 @@
 pub(super) struct KvmHypervisor;
 
 impl Hypervisor for KvmHypervisor {
-    fn mmio_guard_granule(&self) -> Result<usize> {
-        let args = [0u64; 17];
-
-        let granule = checked_hvc64(VENDOR_HYP_KVM_MMIO_GUARD_INFO_FUNC_ID, args)?;
-        Ok(granule.try_into().unwrap())
+    fn mmio_guard_init(&self) -> Result<()> {
+        mmio_guard_enroll()?;
+        let mmio_granule = mmio_guard_granule()?;
+        if mmio_granule != SIZE_4KB {
+            return Err(Error::UnsupportedMmioGuardGranule(mmio_granule));
+        }
+        Ok(())
     }
 
-    fn mmio_guard_enroll(&self) -> Result<()> {
-        let args = [0u64; 17];
-
-        checked_hvc64_expect_zero(VENDOR_HYP_KVM_MMIO_GUARD_ENROLL_FUNC_ID, args)
-    }
-
-    fn mmio_guard_map(&self, ipa: u64) -> Result<()> {
+    fn mmio_guard_map(&self, addr: usize) -> Result<()> {
         let mut args = [0u64; 17];
-        args[0] = ipa;
+        args[0] = page_address(addr);
 
         // TODO(b/277859415): pKVM returns a i32 instead of a i64 in T.
         // Drop this hack once T reaches EoL.
         let is_i32_error_code = |n| u32::try_from(n).ok().filter(|v| (*v as i32) < 0).is_some();
-        match checked_hvc64_expect_zero(VENDOR_HYP_KVM_MMIO_GUARD_MAP_FUNC_ID, args) {
-            Err(Error::Unexpected(e)) if is_i32_error_code(e) => match e as u32 as i32 {
-                -1 => Err(Error::NotSupported),
-                -2 => Err(Error::NotRequired),
-                -3 => Err(Error::InvalidParameter),
-                ret => Err(Error::Unknown(ret as i64)),
+        match smccc::checked_hvc64_expect_zero(VENDOR_HYP_KVM_MMIO_GUARD_MAP_FUNC_ID, args) {
+            Err(smccc::Error::Unexpected(e)) if is_i32_error_code(e) => match e as u32 as i32 {
+                -1 => Err(smccc::Error::NotSupported),
+                -2 => Err(smccc::Error::NotRequired),
+                -3 => Err(smccc::Error::InvalidParameter),
+                ret => Err(smccc::Error::Unknown(ret as i64)),
             },
             res => res,
         }
+        .map_err(|e| Error::HvcError(e, VENDOR_HYP_KVM_MMIO_GUARD_MAP_FUNC_ID))
     }
 
-    fn mmio_guard_unmap(&self, ipa: u64) -> Result<()> {
+    fn mmio_guard_unmap(&self, addr: usize) -> Result<()> {
         let mut args = [0u64; 17];
-        args[0] = ipa;
+        args[0] = page_address(addr);
 
         // TODO(b/277860860): pKVM returns NOT_SUPPORTED for SUCCESS in T.
         // Drop this hack once T reaches EoL.
-        match checked_hvc64_expect_zero(VENDOR_HYP_KVM_MMIO_GUARD_UNMAP_FUNC_ID, args) {
-            Err(Error::NotSupported) | Ok(_) => Ok(()),
-            x => x,
+        match smccc::checked_hvc64_expect_zero(VENDOR_HYP_KVM_MMIO_GUARD_UNMAP_FUNC_ID, args) {
+            Err(smccc::Error::NotSupported) | Ok(_) => Ok(()),
+            Err(e) => Err(Error::HvcError(e, VENDOR_HYP_KVM_MMIO_GUARD_UNMAP_FUNC_ID)),
         }
     }
 
@@ -92,3 +90,27 @@
         Ok(granule.try_into().unwrap())
     }
 }
+
+fn mmio_guard_granule() -> Result<usize> {
+    let args = [0u64; 17];
+
+    let granule = checked_hvc64(VENDOR_HYP_KVM_MMIO_GUARD_INFO_FUNC_ID, args)?;
+    Ok(granule.try_into().unwrap())
+}
+
+fn mmio_guard_enroll() -> Result<()> {
+    let args = [0u64; 17];
+    match smccc::checked_hvc64_expect_zero(VENDOR_HYP_KVM_MMIO_GUARD_ENROLL_FUNC_ID, args) {
+        Ok(_) => Ok(()),
+        Err(smccc::Error::NotSupported) => Err(Error::MmioGuardNotsupported),
+        Err(e) => Err(Error::HvcError(e, VENDOR_HYP_KVM_MMIO_GUARD_ENROLL_FUNC_ID)),
+    }
+}
+
+fn checked_hvc64_expect_zero(function: u32, args: [u64; 17]) -> Result<()> {
+    smccc::checked_hvc64_expect_zero(function, args).map_err(|e| Error::HvcError(e, function))
+}
+
+fn checked_hvc64(function: u32, args: [u64; 17]) -> Result<u64> {
+    smccc::checked_hvc64(function, args).map_err(|e| Error::HvcError(e, function))
+}
diff --git a/libs/hyp/src/lib.rs b/libs/hyp/src/lib.rs
index 676af1d..66c78f4 100644
--- a/libs/hyp/src/lib.rs
+++ b/libs/hyp/src/lib.rs
@@ -16,8 +16,9 @@
 
 #![no_std]
 
+mod error;
 mod hypervisor;
 mod util;
 
+pub use error::{Error, Result};
 pub use hypervisor::{get_hypervisor, Hypervisor};
-pub mod mmio_guard;
diff --git a/libs/hyp/src/mmio_guard.rs b/libs/hyp/src/mmio_guard.rs
deleted file mode 100644
index 84dac64..0000000
--- a/libs/hyp/src/mmio_guard.rs
+++ /dev/null
@@ -1,70 +0,0 @@
-// Copyright 2022, The Android Open Source Project
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-//! Safe MMIO_GUARD support.
-
-use crate::hypervisor::get_hypervisor;
-use crate::util::{page_address, SIZE_4KB};
-use core::{fmt, result};
-
-/// MMIO guard error.
-#[derive(Debug, Clone)]
-pub enum Error {
-    /// Failed the necessary MMIO_GUARD_ENROLL call.
-    EnrollFailed(smccc::Error),
-    /// Failed to obtain the MMIO_GUARD granule size.
-    GranuleQueryFailed(smccc::Error),
-    /// Failed to MMIO_GUARD_MAP a page.
-    MapFailed(smccc::Error),
-    /// Failed to MMIO_GUARD_UNMAP a page.
-    UnmapFailed(smccc::Error),
-    /// The MMIO_GUARD granule used by the hypervisor is not supported.
-    UnsupportedGranule(usize),
-}
-
-impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
-            Self::EnrollFailed(e) => write!(f, "Failed to enroll into MMIO_GUARD: {e}"),
-            Self::GranuleQueryFailed(e) => write!(f, "Failed to get the MMIO_GUARD granule: {e}"),
-            Self::MapFailed(e) => write!(f, "Failed to MMIO_GUARD map: {e}"),
-            Self::UnmapFailed(e) => write!(f, "Failed to MMIO_GUARD unmap: {e}"),
-            Self::UnsupportedGranule(g) => write!(f, "Unsupported MMIO_GUARD granule: {g}"),
-        }
-    }
-}
-
-/// Result type with mmio_guard::Error.
-pub type Result<T> = result::Result<T, Error>;
-
-/// Initializes the hypervisor by enrolling a MMIO guard and checking the memory granule size.
-pub fn init() -> Result<()> {
-    let hyp = get_hypervisor();
-    hyp.mmio_guard_enroll().map_err(Error::EnrollFailed)?;
-    let mmio_granule = hyp.mmio_guard_granule().map_err(Error::GranuleQueryFailed)?;
-    if mmio_granule != SIZE_4KB {
-        return Err(Error::UnsupportedGranule(mmio_granule));
-    }
-    Ok(())
-}
-
-/// Maps a memory address to the hypervisor MMIO guard.
-pub fn map(addr: usize) -> Result<()> {
-    get_hypervisor().mmio_guard_map(page_address(addr)).map_err(Error::MapFailed)
-}
-
-/// Unmaps a memory address from the hypervisor MMIO guard.
-pub fn unmap(addr: usize) -> Result<()> {
-    get_hypervisor().mmio_guard_unmap(page_address(addr)).map_err(Error::UnmapFailed)
-}
diff --git a/pvmfw/src/entry.rs b/pvmfw/src/entry.rs
index e0af856..1309d73 100644
--- a/pvmfw/src/entry.rs
+++ b/pvmfw/src/entry.rs
@@ -25,7 +25,7 @@
 use core::arch::asm;
 use core::num::NonZeroUsize;
 use core::slice;
-use hyp::mmio_guard;
+use hyp::get_hypervisor;
 use log::debug;
 use log::error;
 use log::info;
@@ -172,12 +172,12 @@
     // Use debug!() to avoid printing to the UART if we failed to configure it as only local
     // builds that have tweaked the logger::init() call will actually attempt to log the message.
 
-    mmio_guard::init().map_err(|e| {
+    get_hypervisor().mmio_guard_init().map_err(|e| {
         debug!("{e}");
         RebootReason::InternalError
     })?;
 
-    mmio_guard::map(console::BASE_ADDRESS).map_err(|e| {
+    get_hypervisor().mmio_guard_map(console::BASE_ADDRESS).map_err(|e| {
         debug!("Failed to configure the UART: {e}");
         RebootReason::InternalError
     })?;
@@ -236,7 +236,7 @@
         error!("Failed to unshare MMIO ranges: {e}");
         RebootReason::InternalError
     })?;
-    mmio_guard::unmap(console::BASE_ADDRESS).map_err(|e| {
+    get_hypervisor().mmio_guard_unmap(console::BASE_ADDRESS).map_err(|e| {
         error!("Failed to unshare the UART: {e}");
         RebootReason::InternalError
     })?;
diff --git a/pvmfw/src/memory.rs b/pvmfw/src/memory.rs
index 3f44f8a..2d5eb5c 100644
--- a/pvmfw/src/memory.rs
+++ b/pvmfw/src/memory.rs
@@ -29,7 +29,7 @@
 use core::ops::Range;
 use core::ptr::NonNull;
 use core::result;
-use hyp::{get_hypervisor, mmio_guard};
+use hyp::get_hypervisor;
 use log::error;
 use tinyvec::ArrayVec;
 
@@ -102,8 +102,8 @@
     Overlaps,
     /// Region couldn't be mapped.
     FailedToMap,
-    /// Error from an MMIO guard call.
-    MmioGuard(mmio_guard::Error),
+    /// Error from the interaction with the hypervisor.
+    Hypervisor(hyp::Error),
 }
 
 impl fmt::Display for MemoryTrackerError {
@@ -116,14 +116,14 @@
             Self::OutOfRange => write!(f, "Region is out of the tracked memory address space"),
             Self::Overlaps => write!(f, "New region overlaps with tracked regions"),
             Self::FailedToMap => write!(f, "Failed to map the new region"),
-            Self::MmioGuard(e) => e.fmt(f),
+            Self::Hypervisor(e) => e.fmt(f),
         }
     }
 }
 
-impl From<mmio_guard::Error> for MemoryTrackerError {
-    fn from(e: mmio_guard::Error) -> Self {
-        Self::MmioGuard(e)
+impl From<hyp::Error> for MemoryTrackerError {
+    fn from(e: hyp::Error) -> Self {
+        Self::Hypervisor(e)
     }
 }
 
@@ -213,7 +213,7 @@
         })?;
 
         for page_base in page_iterator(&range) {
-            mmio_guard::map(page_base)?;
+            get_hypervisor().mmio_guard_map(page_base)?;
         }
 
         if self.mmio_regions.try_push(range).is_some() {
@@ -253,7 +253,7 @@
     pub fn mmio_unmap_all(&self) -> Result<()> {
         for region in &self.mmio_regions {
             for page_base in page_iterator(region) {
-                mmio_guard::unmap(page_base)?;
+                get_hypervisor().mmio_guard_unmap(page_base)?;
             }
         }
 
@@ -278,7 +278,7 @@
 /// Gives the KVM host read, write and execute permissions on the given memory range. If the range
 /// is not aligned with the memory protection granule then it will be extended on either end to
 /// align.
-fn share_range(range: &MemoryRange, granule: usize) -> smccc::Result<()> {
+fn share_range(range: &MemoryRange, granule: usize) -> hyp::Result<()> {
     for base in (align_down(range.start, granule)
         .expect("Memory protection granule was not a power of two")..range.end)
         .step_by(granule)
@@ -291,7 +291,7 @@
 /// Removes permission from the KVM host to access the given memory range which was previously
 /// shared. If the range is not aligned with the memory protection granule then it will be extended
 /// on either end to align.
-fn unshare_range(range: &MemoryRange, granule: usize) -> smccc::Result<()> {
+fn unshare_range(range: &MemoryRange, granule: usize) -> hyp::Result<()> {
     for base in (align_down(range.start, granule)
         .expect("Memory protection granule was not a power of two")..range.end)
         .step_by(granule)
@@ -305,7 +305,7 @@
 /// with the host. Returns a pointer to the buffer.
 ///
 /// It will be aligned to the memory sharing granule size supported by the hypervisor.
-pub fn alloc_shared(size: usize) -> smccc::Result<NonNull<u8>> {
+pub fn alloc_shared(size: usize) -> hyp::Result<NonNull<u8>> {
     let layout = shared_buffer_layout(size)?;
     let granule = layout.align();
 
@@ -333,7 +333,7 @@
 ///
 /// The memory must have been allocated by `alloc_shared` with the same size, and not yet
 /// deallocated.
-pub unsafe fn dealloc_shared(vaddr: NonNull<u8>, size: usize) -> smccc::Result<()> {
+pub unsafe fn dealloc_shared(vaddr: NonNull<u8>, size: usize) -> hyp::Result<()> {
     let layout = shared_buffer_layout(size)?;
     let granule = layout.align();
 
@@ -352,7 +352,7 @@
 /// It will be aligned to the memory sharing granule size supported by the hypervisor.
 ///
 /// Panics if `size` is 0.
-fn shared_buffer_layout(size: usize) -> smccc::Result<Layout> {
+fn shared_buffer_layout(size: usize) -> hyp::Result<Layout> {
     assert_ne!(size, 0);
     let granule = get_hypervisor().memory_protection_granule()?;
     let allocated_size =
diff --git a/rialto/Android.bp b/rialto/Android.bp
index 5034bf4..cf81563 100644
--- a/rialto/Android.bp
+++ b/rialto/Android.bp
@@ -13,7 +13,6 @@
         "libbuddy_system_allocator",
         "libhyp",
         "liblog_rust_nostd",
-        "libsmccc",
         "libvmbase",
     ],
     apex_available: ["com.android.virt"],
diff --git a/rialto/src/error.rs b/rialto/src/error.rs
index 8f34676..754e554 100644
--- a/rialto/src/error.rs
+++ b/rialto/src/error.rs
@@ -16,14 +16,14 @@
 
 use aarch64_paging::MapError;
 use core::{fmt, result};
-use hyp::mmio_guard::Error as MmioError;
+use hyp::Error as HypervisorError;
 
 pub type Result<T> = result::Result<T, Error>;
 
 #[derive(Clone, Debug)]
 pub enum Error {
-    /// MMIO guard failed.
-    MmioGuard(MmioError),
+    /// Hypervisor error.
+    Hypervisor(HypervisorError),
     /// Failed when attempting to map some range in the page table.
     PageTableMapping(MapError),
     /// Failed to initialize the logger.
@@ -33,7 +33,7 @@
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            Self::MmioGuard(e) => write!(f, "MMIO guard failed: {e}."),
+            Self::Hypervisor(e) => write!(f, "MMIO guard failed: {e}."),
             Self::PageTableMapping(e) => {
                 write!(f, "Failed when attempting to map some range in the page table: {e}.")
             }
@@ -42,9 +42,9 @@
     }
 }
 
-impl From<MmioError> for Error {
-    fn from(e: MmioError) -> Self {
-        Self::MmioGuard(e)
+impl From<HypervisorError> for Error {
+    fn from(e: HypervisorError) -> Self {
+        Self::Hypervisor(e)
     }
 }
 
diff --git a/rialto/src/main.rs b/rialto/src/main.rs
index 76f5495..99e07b6 100644
--- a/rialto/src/main.rs
+++ b/rialto/src/main.rs
@@ -28,7 +28,7 @@
     paging::{Attributes, MemoryRegion},
 };
 use buddy_system_allocator::LockedHeap;
-use hyp::mmio_guard;
+use hyp::get_hypervisor;
 use log::{debug, error, info};
 use vmbase::{main, power::reboot};
 
@@ -109,11 +109,11 @@
 }
 
 fn try_init_logger() -> Result<()> {
-    match mmio_guard::init() {
+    match get_hypervisor().mmio_guard_init() {
         // pKVM blocks MMIO by default, we need to enable MMIO guard to support logging.
-        Ok(()) => mmio_guard::map(vmbase::console::BASE_ADDRESS)?,
+        Ok(()) => get_hypervisor().mmio_guard_map(vmbase::console::BASE_ADDRESS)?,
         // MMIO guard enroll is not supported in unprotected VM.
-        Err(mmio_guard::Error::EnrollFailed(smccc::Error::NotSupported)) => {}
+        Err(hyp::Error::MmioGuardNotsupported) => {}
         Err(e) => return Err(e.into()),
     };
     vmbase::logger::init(log::LevelFilter::Debug).map_err(|_| Error::LoggerInit)