refactor: repalce PAGE_SIZE with GUEST/HOST_PAGE_SIZE

Firecracker was assumming page sizes for both
host and guest are 4K. But they can differ, so
split into 2 values.

Signed-off-by: Egor Lazarchuk <[email protected]>

Author: ShadowCurse

src/vmm/src/arch/aarch64/mod.rs

@@ -94,7 +94,7 @@ pub fn initrd_load_addr(
     guest_mem: &GuestMemoryMmap,
     initrd_size: usize,
 ) -> Result<u64, ConfigurationError> {
-    let round_to_pagesize = |size| (size + (super::PAGE_SIZE - 1)) & !(super::PAGE_SIZE - 1);
+    let round_to_pagesize = |size| (size + (super::GUEST_PAGE_SIZE - 1)) & !(super::GUEST_PAGE_SIZE - 1);
     match GuestAddress(get_fdt_addr(guest_mem)).checked_sub(round_to_pagesize(initrd_size) as u64) {
         Some(offset) => {
             if guest_mem.address_in_range(offset) {

src/vmm/src/arch/mod.rs

@@ -52,8 +52,11 @@ pub struct InitrdConfig {
     pub size: usize,
 }
 
-/// Default (smallest) memory page size for the supported architectures.
-pub const PAGE_SIZE: usize = 4096;
+/// Default page size for the guest OS.
+pub const GUEST_PAGE_SIZE: usize = 4096;
+
+/// Default page size for the host OS.
+pub const HOST_PAGE_SIZE: usize = 4096;
 
 impl fmt::Display for DeviceType {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {

src/vmm/src/arch/x86_64/mod.rs

@@ -97,7 +97,7 @@ pub fn initrd_load_addr(
         return Err(ConfigurationError::InitrdAddress);
     }
 
-    let align_to_pagesize = |address| address & !(super::PAGE_SIZE - 1);
+    let align_to_pagesize = |address| address & !(super::GUEST_PAGE_SIZE - 1);
     Ok(align_to_pagesize(lowmem_size - initrd_size) as u64)
 }
 

src/vmm/src/builder.rs

@@ -1303,7 +1303,7 @@ pub mod tests {
         use crate::vstate::memory::GuestMemory;
         let image = make_test_bin();
 
-        let mem_size: usize = image.len() * 2 + crate::arch::PAGE_SIZE;
+        let mem_size: usize = image.len() * 2 + crate::arch::GUEST_PAGE_SIZE;
 
         let tempfile = TempFile::new().unwrap();
         let mut tempfile = tempfile.into_file();
@@ -1342,7 +1342,7 @@ pub mod tests {
         let tempfile = TempFile::new().unwrap();
         let mut tempfile = tempfile.into_file();
         tempfile.write_all(&image).unwrap();
-        let gm = single_region_mem_at(crate::arch::PAGE_SIZE as u64 + 1, image.len() * 2);
+        let gm = single_region_mem_at(crate::arch::GUEST_PAGE_SIZE as u64 + 1, image.len() * 2);
 
         let res = load_initrd(&gm, &mut tempfile);
         assert!(

src/vmm/src/devices/virtio/iov_deque.rs

@@ -6,7 +6,7 @@ use std::os::fd::AsRawFd;
 use libc::{c_int, c_void, iovec, off_t, size_t};
 use memfd;
 
-use crate::arch::PAGE_SIZE;
+use crate::arch::HOST_PAGE_SIZE;
 
 #[derive(Debug, thiserror::Error, displaydoc::Display)]
 pub enum IovDequeError {
@@ -93,7 +93,7 @@ unsafe impl<const L: u16> Send for IovDeque<L> {}
 
 impl<const L: u16> IovDeque<L> {
     const BYTES: usize = L as usize * std::mem::size_of::<iovec>();
-    const _ASSERT: () = assert!(Self::BYTES % PAGE_SIZE == 0);
+    const _ASSERT: () = assert!(Self::BYTES % HOST_PAGE_SIZE == 0);
 
     /// Create a [`memfd`] object that represents a single physical page
     fn create_memfd() -> Result<memfd::Memfd, IovDequeError> {

src/vmm/src/devices/virtio/iovec.rs

@@ -821,7 +821,6 @@ mod verification {
     type IoVecBufferMutDefault = super::IoVecBufferMut<FIRECRACKER_MAX_QUEUE_SIZE>;
     type IovDequeDefault = IovDeque<FIRECRACKER_MAX_QUEUE_SIZE>;
 
-    use crate::arch::PAGE_SIZE;
     use crate::devices::virtio::queue::FIRECRACKER_MAX_QUEUE_SIZE;
 
     // Maximum memory size to use for our buffers. For the time being 1KB.