[pvmfw] Extract a library to support various hypervisor backends
This cl extracts a library libhyp from pvmfw to support
various hypervisor backends including kvm.
Bug: 272226230
Test: m pvmfw_img
Change-Id: I5307cb5d6cccc7a01af6bc9c46ae7111c0d51e93
diff --git a/libs/hyp/Android.bp b/libs/hyp/Android.bp
new file mode 100644
index 0000000..bc66190
--- /dev/null
+++ b/libs/hyp/Android.bp
@@ -0,0 +1,18 @@
+package {
+ default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+rust_library_rlib {
+ name: "libhyp",
+ crate_name: "hyp",
+ srcs: ["src/lib.rs"],
+ prefer_rlib: true,
+ rustlibs: [
+ "libsmccc",
+ ],
+ no_stdlibs: true,
+ stdlibs: [
+ "libcore.rust_sysroot",
+ ],
+ apex_available: ["com.android.virt"],
+}
diff --git a/libs/hyp/src/hypervisor/kvm.rs b/libs/hyp/src/hypervisor/kvm.rs
new file mode 100644
index 0000000..a34acc8
--- /dev/null
+++ b/libs/hyp/src/hypervisor/kvm.rs
@@ -0,0 +1,95 @@
+// 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.
+
+//! Wrappers around calls to the KVM hypervisor.
+
+use smccc::{checked_hvc64, checked_hvc64_expect_zero, Error, Result};
+
+const ARM_SMCCC_KVM_FUNC_HYP_MEMINFO: u32 = 0xc6000002;
+const ARM_SMCCC_KVM_FUNC_MEM_SHARE: u32 = 0xc6000003;
+const ARM_SMCCC_KVM_FUNC_MEM_UNSHARE: u32 = 0xc6000004;
+
+const VENDOR_HYP_KVM_MMIO_GUARD_INFO_FUNC_ID: u32 = 0xc6000005;
+const VENDOR_HYP_KVM_MMIO_GUARD_ENROLL_FUNC_ID: u32 = 0xc6000006;
+const VENDOR_HYP_KVM_MMIO_GUARD_MAP_FUNC_ID: u32 = 0xc6000007;
+const VENDOR_HYP_KVM_MMIO_GUARD_UNMAP_FUNC_ID: u32 = 0xc6000008;
+
+/// Queries the memory protection parameters for a protected virtual machine.
+///
+/// Returns the memory protection granule size in bytes.
+pub(super) fn hyp_meminfo() -> Result<u64> {
+ let args = [0u64; 17];
+ checked_hvc64(ARM_SMCCC_KVM_FUNC_HYP_MEMINFO, args)
+}
+
+/// Shares a region of memory with the KVM host, granting it read, write and execute permissions.
+/// The size of the region is equal to the memory protection granule returned by [`hyp_meminfo`].
+pub(super) fn mem_share(base_ipa: u64) -> Result<()> {
+ let mut args = [0u64; 17];
+ args[0] = base_ipa;
+
+ checked_hvc64_expect_zero(ARM_SMCCC_KVM_FUNC_MEM_SHARE, args)
+}
+
+/// Revokes access permission from the KVM host to a memory region previously shared with
+/// [`mem_share`]. The size of the region is equal to the memory protection granule returned by
+/// [`hyp_meminfo`].
+pub(super) fn mem_unshare(base_ipa: u64) -> Result<()> {
+ let mut args = [0u64; 17];
+ args[0] = base_ipa;
+
+ checked_hvc64_expect_zero(ARM_SMCCC_KVM_FUNC_MEM_UNSHARE, args)
+}
+
+pub(super) fn mmio_guard_info() -> Result<u64> {
+ let args = [0u64; 17];
+
+ checked_hvc64(VENDOR_HYP_KVM_MMIO_GUARD_INFO_FUNC_ID, args)
+}
+
+pub(super) fn mmio_guard_enroll() -> Result<()> {
+ let args = [0u64; 17];
+
+ checked_hvc64_expect_zero(VENDOR_HYP_KVM_MMIO_GUARD_ENROLL_FUNC_ID, args)
+}
+
+pub(super) fn mmio_guard_map(ipa: u64) -> Result<()> {
+ let mut args = [0u64; 17];
+ args[0] = ipa;
+
+ // 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)),
+ },
+ res => res,
+ }
+}
+
+pub(super) fn mmio_guard_unmap(ipa: u64) -> Result<()> {
+ let mut args = [0u64; 17];
+ args[0] = ipa;
+
+ // 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,
+ }
+}
diff --git a/libs/hyp/src/hypervisor/mod.rs b/libs/hyp/src/hypervisor/mod.rs
new file mode 100644
index 0000000..5807698
--- /dev/null
+++ b/libs/hyp/src/hypervisor/mod.rs
@@ -0,0 +1,53 @@
+// 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.
+
+//! Wrappers around hypervisor back-ends.
+
+mod kvm;
+
+/// Queries the memory protection parameters for a protected virtual machine.
+///
+/// Returns the memory protection granule size in bytes.
+pub fn hyp_meminfo() -> smccc::Result<u64> {
+ kvm::hyp_meminfo()
+}
+
+/// Shares a region of memory with the host, granting it read, write and execute permissions.
+/// The size of the region is equal to the memory protection granule returned by [`hyp_meminfo`].
+pub fn mem_share(base_ipa: u64) -> smccc::Result<()> {
+ kvm::mem_share(base_ipa)
+}
+
+/// Revokes access permission from the host to a memory region previously shared with
+/// [`mem_share`]. The size of the region is equal to the memory protection granule returned by
+/// [`hyp_meminfo`].
+pub fn mem_unshare(base_ipa: u64) -> smccc::Result<()> {
+ kvm::mem_unshare(base_ipa)
+}
+
+pub(crate) fn mmio_guard_info() -> smccc::Result<u64> {
+ kvm::mmio_guard_info()
+}
+
+pub(crate) fn mmio_guard_enroll() -> smccc::Result<()> {
+ kvm::mmio_guard_enroll()
+}
+
+pub(crate) fn mmio_guard_map(ipa: u64) -> smccc::Result<()> {
+ kvm::mmio_guard_map(ipa)
+}
+
+pub(crate) fn mmio_guard_unmap(ipa: u64) -> smccc::Result<()> {
+ kvm::mmio_guard_unmap(ipa)
+}
diff --git a/libs/hyp/src/lib.rs b/libs/hyp/src/lib.rs
new file mode 100644
index 0000000..f0f0631
--- /dev/null
+++ b/libs/hyp/src/lib.rs
@@ -0,0 +1,23 @@
+// 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.
+
+//! This library provides wrappers around various hypervisor backends.
+
+#![no_std]
+
+mod hypervisor;
+mod util;
+
+pub use hypervisor::{hyp_meminfo, mem_share, mem_unshare};
+pub mod mmio_guard;
diff --git a/libs/hyp/src/mmio_guard.rs b/libs/hyp/src/mmio_guard.rs
new file mode 100644
index 0000000..512eb88
--- /dev/null
+++ b/libs/hyp/src/mmio_guard.rs
@@ -0,0 +1,69 @@
+// 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::{mmio_guard_enroll, mmio_guard_info, mmio_guard_map, mmio_guard_unmap};
+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.
+ InfoFailed(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::InfoFailed(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<()> {
+ mmio_guard_enroll().map_err(Error::EnrollFailed)?;
+ let mmio_granule = mmio_guard_info().map_err(Error::InfoFailed)? as usize;
+ 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<()> {
+ 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<()> {
+ mmio_guard_unmap(page_address(addr)).map_err(Error::UnmapFailed)
+}
diff --git a/libs/hyp/src/util.rs b/libs/hyp/src/util.rs
new file mode 100644
index 0000000..56f94fd
--- /dev/null
+++ b/libs/hyp/src/util.rs
@@ -0,0 +1,22 @@
+// 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.
+
+//! Utility functions.
+
+pub(crate) const SIZE_4KB: usize = 4 << 10;
+
+/// Computes the low memory page address of the 4KiB page containing a given address.
+pub(crate) fn page_address(addr: usize) -> u64 {
+ (addr & !(SIZE_4KB - 1)).try_into().unwrap()
+}