virtio-devices: Introduce new function translating GPAs into GVAs

In anticipation for the vDPA need to translate a GPA back into a GVA, we
extend the existing trait DmaRemapping and AccessPlatform to perform
such operation.

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

virtio-devices/src/device.rs

@@ -209,6 +209,8 @@ pub trait VirtioDevice: Send {
 pub trait DmaRemapping: Send + Sync {
     /// Provide a way to translate GVA address ranges into GPAs.
     fn translate_gva(&self, id: u32, addr: u64) -> std::result::Result<u64, std::io::Error>;
+    /// Provide a way to translate GPA address ranges into GVAs.
+    fn translate_gpa(&self, id: u32, addr: u64) -> std::result::Result<u64, std::io::Error>;
 }
 
 /// Structure to handle device state common to all devices

virtio-devices/src/iommu.rs

@@ -684,7 +684,7 @@ pub struct IommuMapping {
 
 impl DmaRemapping for IommuMapping {
     fn translate_gva(&self, id: u32, addr: u64) -> std::result::Result<u64, std::io::Error> {
-        debug!("Translate addr 0x{:x}", addr);
+        debug!("Translate GVA addr 0x{:x}", addr);
         if let Some(domain) = self.endpoints.read().unwrap().get(&id) {
             if let Some(mapping) = self.mappings.read().unwrap().get(domain) {
                 let range_start = if VIRTIO_IOMMU_PAGE_SIZE_MASK > addr {
@@ -695,7 +695,25 @@ impl DmaRemapping for IommuMapping {
                 for (&key, &value) in mapping.range((Included(&range_start), Included(&addr))) {
                     if addr >= key && addr < key + value.size {
                         let new_addr = addr - key + value.gpa;
-                        debug!("Into new_addr 0x{:x}", new_addr);
+                        debug!("Into GPA addr 0x{:x}", new_addr);
+                        return Ok(new_addr);
+                    }
+                }
+            }
+        }
+
+        debug!("Into same addr...");
+        Ok(addr)
+    }
+
+    fn translate_gpa(&self, id: u32, addr: u64) -> std::result::Result<u64, std::io::Error> {
+        debug!("Translate GPA addr 0x{:x}", addr);
+        if let Some(domain) = self.endpoints.read().unwrap().get(&id) {
+            if let Some(mapping) = self.mappings.read().unwrap().get(domain) {
+                for (&key, &value) in mapping.iter() {
+                    if addr >= value.gpa && addr < value.gpa + value.size {
+                        let new_addr = addr - value.gpa + key;
+                        debug!("Into GVA addr 0x{:x}", new_addr);
                         return Ok(new_addr);
                     }
                 }
@@ -723,6 +741,9 @@ impl AccessPlatform for AccessPlatformMapping {
     fn translate_gva(&self, base: u64, _size: u64) -> std::result::Result<u64, std::io::Error> {
         self.mapping.translate_gva(self.id, base)
     }
+    fn translate_gpa(&self, base: u64, _size: u64) -> std::result::Result<u64, std::io::Error> {
+        self.mapping.translate_gpa(self.id, base)
+    }
 }
 
 pub struct Iommu {

vm-virtio/src/lib.rs

@@ -96,10 +96,13 @@ impl fmt::Display for VirtioDeviceType {
 pub trait AccessPlatform: Send + Sync + Debug {
     /// Provide a way to translate GVA address ranges into GPAs.
     fn translate_gva(&self, base: u64, size: u64) -> std::result::Result<u64, std::io::Error>;
+    /// Provide a way to translate GPA address ranges into GVAs.
+    fn translate_gpa(&self, base: u64, size: u64) -> std::result::Result<u64, std::io::Error>;
 }
 
 pub trait Translatable {
     fn translate_gva(&self, access_platform: Option<&Arc<dyn AccessPlatform>>, len: usize) -> Self;
+    fn translate_gpa(&self, access_platform: Option<&Arc<dyn AccessPlatform>>, len: usize) -> Self;
 }
 
 impl Translatable for GuestAddress {
@@ -110,4 +113,11 @@ impl Translatable for GuestAddress {
             *self
         }
     }
+    fn translate_gpa(&self, access_platform: Option<&Arc<dyn AccessPlatform>>, len: usize) -> Self {
+        if let Some(access_platform) = access_platform {
+            GuestAddress(access_platform.translate_gpa(self.0, len as u64).unwrap())
+        } else {
+            *self
+        }
+    }
 }