chore: upgrade userfaultfd-rs dependency

Upgrade uffd-rs to 0.9.0, which comes with support for UFFDIO_CONTINUE,
so we can drop our homegrown version of it.

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

Author: roypat

src/firecracker/Cargo.toml

@@ -49,7 +49,7 @@ regex = { version = "1.11.2", default-features = false, features = [
 
 # Dev-Dependencies for uffd examples
 serde = { version = "1.0.219", features = ["derive"] }
-userfaultfd = "0.9.0"
+userfaultfd = { version = "0.9.0", features = ["linux5_13"] }
 
 [lints]
 workspace = true

src/firecracker/examples/uffd/fault_all_handler.rs

@@ -10,14 +10,11 @@
 mod uffd_utils;
 
 use std::fs::File;
-use std::os::fd::AsRawFd;
 use std::os::unix::net::UnixListener;
 
 use uffd_utils::{Runtime, UffdHandler};
 use utils::time::{ClockType, get_time_us};
 
-use crate::uffd_utils::uffd_continue;
-
 fn main() {
     let mut args = std::env::args();
     let uffd_sock_path = args.nth(1).expect("No socket path given");
@@ -57,12 +54,10 @@ fn main() {
                     // TODO: we currently ignore the result as we may attempt to
                     // populate the page that is already present as we may receive
                     // multiple minor fault events per page.
-                    let _ = uffd_continue(
-                        uffd_handler.uffd.as_raw_fd(),
-                        addr as _,
-                        uffd_handler.page_size as u64,
-                    )
-                    .inspect_err(|err| println!("Error during uffdio_continue: {:?}", err));
+                    _ = uffd_handler
+                        .uffd
+                        .r#continue(addr, uffd_handler.page_size, true)
+                        .inspect_err(|err| println!("Error during uffdio_continue: {:?}", err));
                 } else {
                     fault_all(uffd_handler, addr);
                 }

src/firecracker/examples/uffd/on_demand_handler.rs

@@ -10,13 +10,10 @@
 mod uffd_utils;
 
 use std::fs::File;
-use std::os::fd::AsRawFd;
 use std::os::unix::net::UnixListener;
 
 use uffd_utils::{Runtime, UffdHandler};
 
-use crate::uffd_utils::uffd_continue;
-
 fn main() {
     let mut args = std::env::args();
     let uffd_sock_path = args.nth(1).expect("No socket path given");
@@ -112,14 +109,12 @@ fn main() {
                                     // TODO: we currently ignore the result as we may attempt to
                                     // populate the page that is already present as we may receive
                                     // multiple minor fault events per page.
-                                    let _ = uffd_continue(
-                                        uffd_handler.uffd.as_raw_fd(),
-                                        addr as _,
-                                        uffd_handler.page_size as u64,
-                                    )
-                                    .inspect_err(|err| {
-                                        println!("uffdio_continue error: {:?}", err)
-                                    });
+                                    let _ = uffd_handler
+                                        .uffd
+                                        .r#continue(addr.cast(), uffd_handler.page_size, true)
+                                        .inspect_err(|err| {
+                                            println!("uffdio_continue error: {:?}", err)
+                                        });
                                 }
                             } else if !uffd_handler.serve_pf(addr.cast(), uffd_handler.page_size) {
                                 deferred_events.push(event);

src/firecracker/examples/uffd/uffd_utils.rs

@@ -18,7 +18,6 @@ use std::ffi::c_void;
 use std::fs::File;
 use std::io::{Read, Write};
 use std::num::NonZero;
-use std::os::fd::RawFd;
 use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd};
 use std::os::unix::net::UnixStream;
 use std::ptr;
@@ -28,47 +27,10 @@ use std::time::Duration;
 use serde::{Deserialize, Serialize};
 use serde_json::{Deserializer, StreamDeserializer};
 use userfaultfd::{Error, Event, Uffd};
-use vmm_sys_util::ioctl::ioctl_with_mut_ref;
-use vmm_sys_util::ioctl_iowr_nr;
 use vmm_sys_util::sock_ctrl_msg::ScmSocket;
 
 use crate::uffd_utils::userfault_bitmap::UserfaultBitmap;
 
-// TODO: remove when UFFDIO_CONTINUE for guest_memfd is available in the crate
-#[repr(C)]
-struct uffdio_continue {
-    range: uffdio_range,
-    mode: u64,
-    mapped: u64,
-}
-
-ioctl_iowr_nr!(UFFDIO_CONTINUE, 0xAA, 0x7, uffdio_continue);
-
-#[repr(C)]
-struct uffdio_range {
-    start: u64,
-    len: u64,
-}
-
-pub fn uffd_continue(uffd: RawFd, fault_addr: u64, len: u64) -> std::io::Result<()> {
-    let mut cont = uffdio_continue {
-        range: uffdio_range {
-            start: fault_addr,
-            len,
-        },
-        mode: 0, // Normal continuation mode
-        mapped: 0,
-    };
-
-    let ret = unsafe { ioctl_with_mut_ref(&uffd, UFFDIO_CONTINUE(), &mut cont) };
-
-    if ret == -1 {
-        return Err(std::io::Error::last_os_error());
-    }
-
-    Ok(())
-}
-
 // This is the same with the one used in src/vmm.
 /// This describes the mapping between Firecracker base virtual address and offset in the
 /// buffer or file backend for a guest memory region. It is used to tell an external
@@ -440,7 +402,9 @@ impl UffdHandler {
             .unwrap()
             .reset_addr_range(offset, len);
 
-        uffd_continue(self.uffd.as_raw_fd(), dst, len as u64).expect("uffd_continue");
+        self.uffd
+            .r#continue(dst as _, len, true)
+            .expect("uffd_continue");
 
         true
     }

src/vmm/Cargo.toml

@@ -48,7 +48,7 @@ serde_json = "1.0.143"
 slab = "0.4.11"
 thiserror = "2.0.16"
 timerfd = "1.5.0"
-userfaultfd = "0.9.0"
+userfaultfd = { version = "0.9.0", features = ["linux5_13"] }
 utils = { path = "../utils" }
 uuid = "1.18.1"
 vhost = { version = "0.14.0", features = ["vhost-user-frontend"] }

src/vmm/src/persist.rs

@@ -497,9 +497,6 @@ pub enum GuestMemoryFromUffdError {
     HugetlbfsSnapshot,
 }
 
-// TODO remove these when the UFFD crate supports minor faults for guest_memfd
-const UFFDIO_REGISTER_MODE_MINOR: u64 = 1 << 2;
-
 type GuestMemoryResult =
     Result<(Vec<GuestRegionMmap>, Option<Uffd>, Option<UnixStream>), GuestMemoryFromUffdError>;
 
@@ -535,7 +532,7 @@ pub fn guest_memory_from_uffd(
     let mut fds = vec![uffd.as_raw_fd()];
 
     if let Some(gmem) = guest_memfd_fd {
-        mode = RegisterMode::from_bits_retain(UFFDIO_REGISTER_MODE_MINOR);
+        mode = RegisterMode::MINOR;
         fds.push(gmem);
         fds.push(
             userfault_bitmap_memfd