virtio-devices: pmem: Handle descriptor address translation

Since we're trying to move away from the translation happening in the
virtio-queue crate, the device itself is performing the address
translation when needed.

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

virtio-devices/src/pmem.rs

@@ -27,7 +27,7 @@ use std::sync::atomic::AtomicBool;
 use std::sync::{Arc, Barrier};
 use versionize::{VersionMap, Versionize, VersionizeResult};
 use versionize_derive::Versionize;
-use virtio_queue::{DescriptorChain, Queue};
+use virtio_queue::{AccessPlatform, DescriptorChain, Queue};
 use vm_memory::{
     Address, ByteValued, Bytes, GuestAddress, GuestMemoryAtomic, GuestMemoryError,
     GuestMemoryLoadGuard,
@@ -118,6 +118,7 @@ struct Request {
 impl Request {
     fn parse(
         desc_chain: &mut DescriptorChain<GuestMemoryLoadGuard<GuestMemoryMmap>>,
+        access_platform: Option<&Arc<dyn AccessPlatform>>,
     ) -> result::Result<Request, Error> {
         let desc = desc_chain.next().ok_or(Error::DescriptorChainTooShort)?;
         // The descriptor contains the request type which MUST be readable.
@@ -129,9 +130,19 @@ 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)
             .map_err(Error::GuestMemory)?;
 
         let request_type = match request.type_ {
@@ -150,9 +161,19 @@ 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,
         })
     }
 }
@@ -164,6 +185,7 @@ struct PmemEpollHandler {
     queue_evt: EventFd,
     kill_evt: EventFd,
     pause_evt: EventFd,
+    access_platform: Option<Arc<dyn AccessPlatform>>,
 }
 
 impl PmemEpollHandler {
@@ -171,7 +193,7 @@ impl PmemEpollHandler {
         let mut used_desc_heads = [(0, 0); QUEUE_SIZE as usize];
         let mut used_count = 0;
         for mut desc_chain in self.queue.iter().unwrap() {
-            let len = match Request::parse(&mut desc_chain) {
+            let len = match Request::parse(&mut desc_chain, self.access_platform.as_ref()) {
                 Ok(ref req) if (req.type_ == RequestType::Flush) => {
                     let status_code = match self.disk.sync_all() {
                         Ok(()) => VIRTIO_PMEM_RESP_TYPE_OK,
@@ -388,6 +410,7 @@ impl VirtioDevice for Pmem {
                 queue_evt: queue_evts.remove(0),
                 kill_evt,
                 pause_evt,
+                access_platform: self.common.access_platform.clone(),
             };
 
             let paused = self.common.paused.clone();
@@ -424,6 +447,10 @@ impl VirtioDevice for Pmem {
     fn userspace_mappings(&self) -> Vec<UserspaceMapping> {
         vec![self.mapping.clone()]
     }
+
+    fn set_access_platform(&mut self, access_platform: Arc<dyn AccessPlatform>) {
+        self.common.set_access_platform(access_platform)
+    }
 }
 
 impl Pausable for Pmem {