Add wrappers for memory sharing HVCs.
Bug: 261439403
Test: Ran pVM firmware manually.
Change-Id: Ic63863aff8945c8c84641c8777db7ccb8d255e8f
diff --git a/pvmfw/src/helpers.rs b/pvmfw/src/helpers.rs
index f1ff36d..6c35d91 100644
--- a/pvmfw/src/helpers.rs
+++ b/pvmfw/src/helpers.rs
@@ -44,6 +44,17 @@
}
}
+/// Aligns the given address to the given alignment, if it is a power of two.
+///
+/// Returns `None` if the alignment isn't a power of two.
+pub const fn align_down(addr: usize, alignment: usize) -> Option<usize> {
+ if !alignment.is_power_of_two() {
+ None
+ } else {
+ Some(unchecked_align_down(addr, alignment))
+ }
+}
+
/// Computes the address of the 4KiB page containing a given address.
pub const fn page_4kb_of(addr: usize) -> usize {
unchecked_align_down(addr, SIZE_4KB)
diff --git a/pvmfw/src/hvc.rs b/pvmfw/src/hvc.rs
index 66f7977..dc99303 100644
--- a/pvmfw/src/hvc.rs
+++ b/pvmfw/src/hvc.rs
@@ -17,11 +17,41 @@
use crate::smccc::{self, checked_hvc64, checked_hvc64_expect_zero};
use log::info;
+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 fn hyp_meminfo() -> smccc::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 fn mem_share(base_ipa: u64) -> smccc::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 fn mem_unshare(base_ipa: u64) -> smccc::Result<()> {
+ let mut args = [0u64; 17];
+ args[0] = base_ipa;
+
+ checked_hvc64_expect_zero(ARM_SMCCC_KVM_FUNC_MEM_UNSHARE, args)
+}
+
pub fn mmio_guard_info() -> smccc::Result<u64> {
let args = [0u64; 17];
diff --git a/pvmfw/src/memory.rs b/pvmfw/src/memory.rs
index 892089e..5e4874f 100644
--- a/pvmfw/src/memory.rs
+++ b/pvmfw/src/memory.rs
@@ -14,9 +14,11 @@
//! Low-level allocation and tracking of main memory.
-use crate::helpers::{self, page_4kb_of, SIZE_4KB};
+use crate::helpers::{self, align_down, page_4kb_of, SIZE_4KB};
+use crate::hvc::{hyp_meminfo, mem_share, mem_unshare};
use crate::mmio_guard;
use crate::mmu;
+use crate::smccc;
use core::cmp::max;
use core::cmp::min;
use core::fmt;
@@ -267,6 +269,36 @@
}
}
+/// 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.
+#[allow(unused)]
+pub fn share_range(range: &MemoryRange) -> smccc::Result<()> {
+ let granule = hyp_meminfo()? as usize;
+ for base in (align_down(range.start, granule)
+ .expect("Memory protection granule was not a power of two")..range.end)
+ .step_by(granule)
+ {
+ mem_share(base as u64)?;
+ }
+ Ok(())
+}
+
+/// 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.
+#[allow(unused)]
+pub fn unshare_range(range: &MemoryRange) -> smccc::Result<()> {
+ let granule = hyp_meminfo()? as usize;
+ for base in (align_down(range.start, granule)
+ .expect("Memory protection granule was not a power of two")..range.end)
+ .step_by(granule)
+ {
+ mem_unshare(base as u64)?;
+ }
+ Ok(())
+}
+
/// Returns an iterator which yields the base address of each 4 KiB page within the given range.
fn page_iterator(range: &MemoryRange) -> impl Iterator<Item = usize> {
(page_4kb_of(range.start)..range.end).step_by(SIZE_4KB)