fix: Avoid using deprecated vm-memory functions

With vm-memory 0.13.0, we introduced versions of the Read and Write
traits for operations on guest memory (`VolatileRead` and
`VolatileWrite`). These replace various `Read` and `Write` based APIs
that had suboptional performance due to requiring to first copy all data
from guest memory to hypervisor memory to ensure soundness. See also
rust-vmm/vm-memory#217.

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

Cargo.toml

@@ -22,11 +22,11 @@ elf = []
 pe = []
 
 [dependencies]
-vm-memory = "0.13.0"
+vm-memory = "0.13.1"
 
 [dev-dependencies]
 criterion = { version = "0.5.1", features = ["html_reports"] }
-vm-memory = { version = "0.13.0", features = ["backend-mmap"] }
+vm-memory = { version = "0.13.1", features = ["backend-mmap"] }
 
 [[bench]]
 name = "main"

src/loader/mod.rs

@@ -24,7 +24,7 @@ use std::io::{Read, Seek};
 
 #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 use vm_memory::ByteValued;
-use vm_memory::{Address, Bytes, GuestAddress, GuestMemory, GuestUsize};
+use vm_memory::{Address, Bytes, GuestAddress, GuestMemory, GuestUsize, ReadVolatile};
 
 #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 pub use crate::loader_gen::bootparam;
@@ -176,7 +176,7 @@ pub trait KernelLoader {
         highmem_start_address: Option<GuestAddress>,
     ) -> Result<KernelLoaderResult>
     where
-        F: Read + Seek;
+        F: Read + ReadVolatile + Seek;
 }
 
 #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]

src/loader/x86_64/bzimage/bzimage

@@ -12,10 +12,9 @@
 #![cfg(all(feature = "bzimage", any(target_arch = "x86", target_arch = "x86_64")))]
 
 use std::fmt;
-use std::io::{Read, Seek, SeekFrom};
-use std::mem;
+use std::io::{Seek, SeekFrom};
 
-use vm_memory::{Address, ByteValued, Bytes, GuestAddress, GuestMemory, GuestUsize};
+use vm_memory::{Address, ByteValued, GuestAddress, GuestMemory, GuestUsize, ReadVolatile};
 
 use super::super::{
     bootparam, Error as KernelLoaderError, KernelLoader, KernelLoaderResult, Result,
@@ -108,7 +107,7 @@ impl KernelLoader for BzImage {
         highmem_start_address: Option<GuestAddress>,
     ) -> Result<KernelLoaderResult>
     where
-        F: Read + Seek,
+        F: ReadVolatile + Seek,
     {
         let mut kernel_size = kernel_image
             .seek(SeekFrom::End(0))
@@ -118,9 +117,8 @@ impl KernelLoader for BzImage {
             .map_err(|_| Error::SeekBzImageHeader)?;
 
         let mut boot_header = bootparam::setup_header::default();
-        boot_header
-            .as_bytes()
-            .read_from(0, kernel_image, mem::size_of::<bootparam::setup_header>())
+        kernel_image
+            .read_volatile(&mut boot_header.as_bytes())
             .map_err(|_| Error::ReadBzImageHeader)?;
 
         // If the `HdrS` magic number is not found at offset 0x202, the boot protocol version is
@@ -172,7 +170,7 @@ impl KernelLoader for BzImage {
             .seek(SeekFrom::Start(setup_size as u64))
             .map_err(|_| Error::SeekBzImageCompressedKernel)?;
         guest_mem
-            .read_exact_from(mem_offset, kernel_image, kernel_size)
+            .read_exact_volatile_from(mem_offset, kernel_image, kernel_size)
             .map_err(|_| Error::ReadBzImageCompressedKernel)?;
 
         loader_result.kernel_end = mem_offset

src/loader/x86_64/bzimage/mod.rs

@@ -17,7 +17,7 @@ use std::io::{Read, Seek, SeekFrom};
 use std::mem;
 use std::result;
 
-use vm_memory::{Address, ByteValued, Bytes, GuestAddress, GuestMemory, GuestUsize};
+use vm_memory::{Address, ByteValued, GuestAddress, GuestMemory, GuestUsize, ReadVolatile};
 
 use crate::loader::{Error as KernelLoaderError, KernelLoader, KernelLoaderResult, Result};
 use crate::loader_gen::elf;
@@ -205,7 +205,7 @@ impl KernelLoader for Elf {
         highmem_start_address: Option<GuestAddress>,
     ) -> Result<KernelLoaderResult>
     where
-        F: Read + Seek,
+        F: Read + ReadVolatile + Seek,
     {
         kernel_image.rewind().map_err(|_| Error::SeekElfStart)?;
 
@@ -281,7 +281,7 @@ impl KernelLoader for Elf {
             };
 
             guest_mem
-                .read_exact_from(mem_offset, kernel_image, phdr.p_filesz as usize)
+                .read_exact_volatile_from(mem_offset, kernel_image, phdr.p_filesz as usize)
                 .map_err(|_| Error::ReadKernelImage)?;
 
             let kernel_end = mem_offset
@@ -309,7 +309,7 @@ const PVH_NOTE_STR_SZ: usize = 4;
 /// are found in the note header.
 fn parse_elf_note<F>(phdr: &elf::Elf64_Phdr, kernel_image: &mut F) -> Result<PvhBootCapability>
 where
-    F: Read + Seek,
+    F: Read + ReadVolatile + Seek,
 {
     // Type of note header that encodes a 32-bit entry point address to boot a guest kernel using
     // the PVH boot protocol.