vm-virtio: Define and implement Translatable trait

This new trait simplifies the address translation of a GuestAddress by
having GuestAddress implementing it.

The three crates virtio-devices, block_util and net_util have been
updated accordingly to rely on this new trait, helping with code
readability and limiting the amount of duplicated code.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

block_util/src/lib.rs

@@ -40,7 +40,7 @@ use vm_memory::{
     bitmap::AtomicBitmap, bitmap::Bitmap, ByteValued, Bytes, GuestAddress, GuestMemory,
     GuestMemoryError, GuestMemoryLoadGuard,
 };
-use vm_virtio::AccessPlatform;
+use vm_virtio::{AccessPlatform, Translatable};
 use vmm_sys_util::eventfd::EventFd;
 
 type GuestMemoryMmap = vm_memory::GuestMemoryMmap<AtomicBitmap>;
@@ -207,15 +207,9 @@ impl Request {
             return Err(Error::UnexpectedWriteOnlyDescriptor);
         }
 
-        let hdr_desc_addr = if let Some(access_platform) = access_platform {
+        let hdr_desc_addr = hdr_desc
-            GuestAddress(
+            .addr()
-                access_platform
+            .translate(access_platform, hdr_desc.len() as usize);
-                    .translate(hdr_desc.addr().0, u64::from(hdr_desc.len()))
-                    .unwrap(),
-            )
-        } else {
-            hdr_desc.addr()
-        };
 
         let mut req = Request {
             request_type: request_type(desc_chain.memory(), hdr_desc_addr)?,
@@ -254,17 +248,10 @@ impl Request {
                     return Err(Error::UnexpectedReadOnlyDescriptor);
                 }
 
-                let desc_addr = if let Some(access_platform) = access_platform {
+                req.data_descriptors.push((
-                    GuestAddress(
+                    desc.addr().translate(access_platform, desc.len() as usize),
-                        access_platform
+                    desc.len(),
-                            .translate(desc.addr().0, u64::from(desc.len()))
+                ));
-                            .unwrap(),
-                    )
-                } else {
-                    desc.addr()
-                };
-
-                req.data_descriptors.push((desc_addr, desc.len()));
                 desc = desc_chain
                     .next()
                     .ok_or(Error::DescriptorChainTooShort)
@@ -285,15 +272,9 @@ impl Request {
             return Err(Error::DescriptorLengthTooSmall);
         }
 
-        req.status_addr = if let Some(access_platform) = access_platform {
+        req.status_addr = status_desc
-            GuestAddress(
+            .addr()
-                access_platform
+            .translate(access_platform, status_desc.len() as usize);
-                    .translate(status_desc.addr().0, u64::from(status_desc.len()))
-                    .unwrap(),
-            )
-        } else {
-            status_desc.addr()
-        };
 
         Ok(req)
     }

net_util/src/ctrl_queue.rs

@@ -14,8 +14,8 @@ use virtio_bindings::bindings::virtio_net::{
     VIRTIO_NET_F_GUEST_UFO, VIRTIO_NET_OK,
 };
 use virtio_queue::Queue;
-use vm_memory::{ByteValued, Bytes, GuestAddress, GuestMemoryAtomic, GuestMemoryError};
+use vm_memory::{ByteValued, Bytes, GuestMemoryAtomic, GuestMemoryError};
-use vm_virtio::AccessPlatform;
+use vm_virtio::{AccessPlatform, Translatable};
 
 #[derive(Debug)]
 pub enum Error {
@@ -65,44 +65,22 @@ impl CtrlQueue {
         for mut desc_chain in queue.iter().map_err(Error::QueueIterator)? {
             let ctrl_desc = desc_chain.next().ok_or(Error::NoControlHeaderDescriptor)?;
 
-            let ctrl_desc_addr = if let Some(access_platform) = access_platform {
-                GuestAddress(
-                    access_platform
-                        .translate(ctrl_desc.addr().0, u64::from(ctrl_desc.len()))
-                        .unwrap(),
-                )
-            } else {
-                ctrl_desc.addr()
-            };
-
             let ctrl_hdr: ControlHeader = desc_chain
                 .memory()
-                .read_obj(ctrl_desc_addr)
+                .read_obj(
+                    ctrl_desc
+                        .addr()
+                        .translate(access_platform, ctrl_desc.len() as usize),
+                )
                 .map_err(Error::GuestMemory)?;
             let data_desc = desc_chain.next().ok_or(Error::NoDataDescriptor)?;
 
-            let data_desc_addr = if let Some(access_platform) = access_platform {
+            let data_desc_addr = data_desc
-                GuestAddress(
+                .addr()
-                    access_platform
+                .translate(access_platform, data_desc.len() as usize);
-                        .translate(data_desc.addr().0, u64::from(data_desc.len()))
-                        .unwrap(),
-                )
-            } else {
-                data_desc.addr()
-            };
 
             let status_desc = desc_chain.next().ok_or(Error::NoStatusDescriptor)?;
 
-            let status_desc_addr = if let Some(access_platform) = access_platform {
-                GuestAddress(
-                    access_platform
-                        .translate(status_desc.addr().0, u64::from(status_desc.len()))
-                        .unwrap(),
-                )
-            } else {
-                status_desc.addr()
-            };
-
             let ok = match u32::from(ctrl_hdr.class) {
                 VIRTIO_NET_CTRL_MQ => {
                     let queue_pairs = desc_chain
@@ -154,7 +132,9 @@ impl CtrlQueue {
                 .memory()
                 .write_obj(
                     if ok { VIRTIO_NET_OK } else { VIRTIO_NET_ERR } as u8,
-                    status_desc_addr,
+                    status_desc
+                        .addr()
+                        .translate(access_platform, status_desc.len() as usize),
                 )
                 .map_err(Error::GuestMemory)?;
             let len = ctrl_desc.len() + data_desc.len() + status_desc.len();

net_util/src/queue_pair.rs

@@ -11,8 +11,8 @@ use std::os::unix::io::{AsRawFd, RawFd};
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::Arc;
 use virtio_queue::Queue;
-use vm_memory::{Bytes, GuestAddress, GuestMemory, GuestMemoryAtomic};
+use vm_memory::{Bytes, GuestMemory, GuestMemoryAtomic};
-use vm_virtio::AccessPlatform;
+use vm_virtio::{AccessPlatform, Translatable};
 
 #[derive(Clone)]
 pub struct TxVirtio {
@@ -60,16 +60,7 @@ impl TxVirtio {
 
                 let mut iovecs = Vec::new();
                 while let Some(desc) = next_desc {
-                    let desc_addr = if let Some(access_platform) = access_platform {
+                    let desc_addr = desc.addr().translate(access_platform, desc.len() as usize);
-                        GuestAddress(
-                            access_platform
-                                .translate(desc.addr().0, u64::from(desc.len()))
-                                .unwrap(),
-                        )
-                    } else {
-                        desc.addr()
-                    };
-
                     if !desc.is_write_only() && desc.len() > 0 {
                         let buf = desc_chain
                             .memory()
@@ -195,31 +186,18 @@ impl RxVirtio {
                     .next()
                     .ok_or(NetQueuePairError::DescriptorChainTooShort)?;
 
-                let desc_addr = if let Some(access_platform) = access_platform {
+                let num_buffers_addr = desc_chain
-                    GuestAddress(
+                    .memory()
-                        access_platform
+                    .checked_offset(
-                            .translate(desc.addr().0, u64::from(desc.len()))
+                        desc.addr().translate(access_platform, desc.len() as usize),
-                            .unwrap(),
+                        10,
                     )
-                } else {
+                    .unwrap();
-                    desc.addr()
-                };
-
-                let num_buffers_addr = desc_chain.memory().checked_offset(desc_addr, 10).unwrap();
                 let mut next_desc = Some(desc);
 
                 let mut iovecs = Vec::new();
                 while let Some(desc) = next_desc {
-                    let desc_addr = if let Some(access_platform) = access_platform {
+                    let desc_addr = desc.addr().translate(access_platform, desc.len() as usize);
-                        GuestAddress(
-                            access_platform
-                                .translate(desc.addr().0, u64::from(desc.len()))
-                                .unwrap(),
-                        )
-                    } else {
-                        desc.addr()
-                    };
-
                     if desc.is_write_only() && desc.len() > 0 {
                         let buf = desc_chain
                             .memory()

virtio-devices/src/console.rs

@@ -25,10 +25,10 @@ use std::sync::{Arc, Barrier, Mutex};
 use versionize::{VersionMap, Versionize, VersionizeResult};
 use versionize_derive::Versionize;
 use virtio_queue::Queue;
-use vm_memory::{ByteValued, Bytes, GuestAddress, GuestMemoryAtomic};
+use vm_memory::{ByteValued, Bytes, GuestMemoryAtomic};
 use vm_migration::VersionMapped;
 use vm_migration::{Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable};
-use vm_virtio::AccessPlatform;
+use vm_virtio::{AccessPlatform, Translatable};
 use vmm_sys_util::eventfd::EventFd;
 
 const QUEUE_SIZE: u16 = 256;
@@ -148,20 +148,11 @@ impl ConsoleEpollHandler {
             let len = cmp::min(desc.len() as u32, in_buffer.len() as u32);
             let source_slice = in_buffer.drain(..len as usize).collect::<Vec<u8>>();
 
-            let desc_addr = if let Some(access_platform) = &self.access_platform {
+            if let Err(e) = desc_chain.memory().write_slice(
-                GuestAddress(
+                &source_slice[..],
-                    access_platform
-                        .translate(desc.addr().0, u64::from(desc.len()))
-                        .unwrap(),
-                )
-            } else {
                 desc.addr()
-            };
+                    .translate(self.access_platform.as_ref(), desc.len() as usize),
-
+            ) {
-            if let Err(e) = desc_chain
-                .memory()
-                .write_slice(&source_slice[..], desc_addr)
-            {
                 error!("Failed to write slice: {:?}", e);
                 avail_iter.go_to_previous_position();
                 break;
@@ -197,19 +188,12 @@ impl ConsoleEpollHandler {
         for mut desc_chain in trans_queue.iter().unwrap() {
             let desc = desc_chain.next().unwrap();
             if let Some(ref mut out) = self.endpoint.out_file() {
-                let desc_addr = if let Some(access_platform) = &self.access_platform {
+                let _ = desc_chain.memory().write_to(
-                    GuestAddress(
-                        access_platform
-                            .translate(desc.addr().0, u64::from(desc.len()))
-                            .unwrap(),
-                    )
-                } else {
                     desc.addr()
-                };
+                        .translate(self.access_platform.as_ref(), desc.len() as usize),
-
+                    out,
-                let _ = desc_chain
+                    desc.len() as usize,
-                    .memory()
+                );
-                    .write_to(desc_addr, out, desc.len() as usize);
                 let _ = out.flush();
             }
             used_desc_heads[used_count] = (desc_chain.head_index(), desc.len());

virtio-devices/src/pmem.rs

@@ -34,7 +34,7 @@ use vm_memory::{
 };
 use vm_migration::VersionMapped;
 use vm_migration::{Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable};
-use vm_virtio::AccessPlatform;
+use vm_virtio::{AccessPlatform, Translatable};
 use vmm_sys_util::eventfd::EventFd;
 
 const QUEUE_SIZE: u16 = 256;
@@ -131,19 +131,9 @@ impl Request {
             return Err(Error::InvalidRequest);
         }
 
-        let desc_addr = if let Some(access_platform) = access_platform {
-            GuestAddress(
-                access_platform
-                    .translate(desc.addr().0, u64::from(desc.len()))
-                    .unwrap(),
-            )
-        } else {
-            desc.addr()
-        };
-
         let request: VirtioPmemReq = desc_chain
             .memory()
-            .read_obj(desc_addr)
+            .read_obj(desc.addr().translate(access_platform, desc.len() as usize))
             .map_err(Error::GuestMemory)?;
 
         let request_type = match request.type_ {
@@ -162,19 +152,11 @@ impl Request {
             return Err(Error::BufferLengthTooSmall);
         }
 
-        let status_desc_addr = if let Some(access_platform) = access_platform {
-            GuestAddress(
-                access_platform
-                    .translate(status_desc.addr().0, u64::from(status_desc.len()))
-                    .unwrap(),
-            )
-        } else {
-            status_desc.addr()
-        };
-
         Ok(Request {
             type_: request_type,
-            status_addr: status_desc_addr,
+            status_addr: status_desc
+                .addr()
+                .translate(access_platform, status_desc.len() as usize),
         })
     }
 }

virtio-devices/src/rng.rs

@@ -22,10 +22,10 @@ use std::sync::{Arc, Barrier};
 use versionize::{VersionMap, Versionize, VersionizeResult};
 use versionize_derive::Versionize;
 use virtio_queue::Queue;
-use vm_memory::{Bytes, GuestAddress, GuestMemoryAtomic};
+use vm_memory::{Bytes, GuestMemoryAtomic};
 use vm_migration::VersionMapped;
 use vm_migration::{Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable};
-use vm_virtio::AccessPlatform;
+use vm_virtio::{AccessPlatform, Translatable};
 use vmm_sys_util::eventfd::EventFd;
 
 const QUEUE_SIZE: u16 = 256;
@@ -56,20 +56,15 @@ impl RngEpollHandler {
 
             // Drivers can only read from the random device.
             if desc.is_write_only() {
-                let desc_addr = if let Some(access_platform) = &self.access_platform {
-                    GuestAddress(
-                        access_platform
-                            .translate(desc.addr().0, u64::from(desc.len()))
-                            .unwrap(),
-                    )
-                } else {
-                    desc.addr()
-                };
-
                 // Fill the read with data from the random device on the host.
                 if desc_chain
                     .memory()
-                    .read_from(desc_addr, &mut self.random_file, desc.len() as usize)
+                    .read_from(
+                        desc.addr()
+                            .translate(self.access_platform.as_ref(), desc.len() as usize),
+                        &mut self.random_file,
+                        desc.len() as usize,
+                    )
                     .is_ok()
                 {
                     len = desc.len();

virtio-devices/src/vsock/packet.rs

@@ -22,8 +22,8 @@ use super::defs;
 use super::{Result, VsockError};
 use crate::{get_host_address_range, GuestMemoryMmap};
 use virtio_queue::DescriptorChain;
-use vm_memory::{GuestAddress, GuestMemoryLoadGuard};
+use vm_memory::GuestMemoryLoadGuard;
-use vm_virtio::AccessPlatform;
+use vm_virtio::{AccessPlatform, Translatable};
 
 // The vsock packet header is defined by the C struct:
 //
@@ -124,18 +124,12 @@ impl VsockPacket {
             return Err(VsockError::HdrDescTooSmall(head.len()));
         }
 
-        let head_addr = if let Some(access_platform) = access_platform {
-            GuestAddress(
-                access_platform
-                    .translate(head.addr().0, u64::from(head.len()))
-                    .unwrap(),
-            )
-        } else {
-            head.addr()
-        };
-
         let mut pkt = Self {
-            hdr: get_host_address_range(desc_chain.memory(), head_addr, VSOCK_PKT_HDR_SIZE)
+            hdr: get_host_address_range(
+                desc_chain.memory(),
+                head.addr().translate(access_platform, head.len() as usize),
+                VSOCK_PKT_HDR_SIZE,
+            )
             .ok_or(VsockError::GuestMemory)? as *mut u8,
             buf: None,
             buf_size: 0,
@@ -166,19 +160,15 @@ impl VsockPacket {
             return Err(VsockError::BufDescTooSmall);
         }
 
-        let buf_desc_addr = if let Some(access_platform) = access_platform {
-            GuestAddress(
-                access_platform
-                    .translate(buf_desc.addr().0, u64::from(buf_desc.len()))
-                    .unwrap(),
-            )
-        } else {
-            buf_desc.addr()
-        };
-
         pkt.buf_size = buf_desc.len() as usize;
         pkt.buf = Some(
-            get_host_address_range(desc_chain.memory(), buf_desc_addr, pkt.buf_size)
+            get_host_address_range(
+                desc_chain.memory(),
+                buf_desc
+                    .addr()
+                    .translate(access_platform, buf_desc.len() as usize),
+                pkt.buf_size,
+            )
             .ok_or(VsockError::GuestMemory)? as *mut u8,
         );
 
@@ -214,28 +204,21 @@ impl VsockPacket {
         let buf_desc = desc_chain.next().ok_or(VsockError::BufDescMissing)?;
         let buf_size = buf_desc.len() as usize;
 
-        let (head_addr, buf_desc_addr) = if let Some(access_platform) = access_platform {
-            (
-                GuestAddress(
-                    access_platform
-                        .translate(head.addr().0, u64::from(head.len()))
-                        .unwrap(),
-                ),
-                GuestAddress(
-                    access_platform
-                        .translate(buf_desc.addr().0, u64::from(buf_desc.len()))
-                        .unwrap(),
-                ),
-            )
-        } else {
-            (head.addr(), buf_desc.addr())
-        };
-
         Ok(Self {
-            hdr: get_host_address_range(desc_chain.memory(), head_addr, VSOCK_PKT_HDR_SIZE)
+            hdr: get_host_address_range(
+                desc_chain.memory(),
+                head.addr().translate(access_platform, head.len() as usize),
+                VSOCK_PKT_HDR_SIZE,
+            )
             .ok_or(VsockError::GuestMemory)? as *mut u8,
             buf: Some(
-                get_host_address_range(desc_chain.memory(), buf_desc_addr, buf_size)
+                get_host_address_range(
+                    desc_chain.memory(),
+                    buf_desc
+                        .addr()
+                        .translate(access_platform, buf_desc.len() as usize),
+                    buf_size,
+                )
                 .ok_or(VsockError::GuestMemory)? as *mut u8,
             ),
             buf_size,

vm-virtio/src/lib.rs

@@ -11,6 +11,9 @@
 //! Implements virtio queues
 
 use std::fmt::{self, Debug};
+use std::sync::Arc;
+
+use vm_memory::GuestAddress;
 
 pub mod queue;
 pub use queue::*;
@@ -94,3 +97,18 @@ pub trait AccessPlatform: Send + Sync + Debug {
     /// Provide a way to translate address ranges.
     fn translate(&self, base: u64, size: u64) -> std::result::Result<u64, std::io::Error>;
 }
+
+pub trait Translatable {
+    #[must_use]
+    fn translate(&self, access_platform: Option<&Arc<dyn AccessPlatform>>, len: usize) -> Self;
+}
+
+impl Translatable for GuestAddress {
+    fn translate(&self, access_platform: Option<&Arc<dyn AccessPlatform>>, len: usize) -> Self {
+        if let Some(access_platform) = access_platform {
+            GuestAddress(access_platform.translate(self.0, len as u64).unwrap())
+        } else {
+            *self
+        }
+    }
+}