xen: begin work on xen grant mappings

crates/xen/xengnt/src/lib.rs

@@ -0,0 +1,142 @@
+pub mod error;
+pub mod sys;
+
+use error::{Error, Result};
+use std::{
+    fs::{File, OpenOptions},
+    os::fd::AsRawFd,
+};
+use sys::{
+    AllocGref, DeallocGref, GetOffsetForVaddr, GrantRef, MapGrantRef, SetMaxGrants, UnmapGrantRef,
+    UnmapNotify, UNMAP_NOTIFY_CLEAR_BYTE, UNMAP_NOTIFY_SEND_EVENT,
+};
+
+pub struct GrantDevice {
+    handle: File,
+}
+
+impl GrantDevice {
+    pub fn open() -> Result<GrantDevice> {
+        let handle = OpenOptions::new()
+            .read(true)
+            .write(true)
+            .open("/dev/xen/gntdev")?;
+        Ok(GrantDevice { handle })
+    }
+
+    pub fn map_grant_ref(&self, count: u32) -> Result<(u64, Vec<GrantRef>)> {
+        let refs: Vec<GrantRef> = vec![
+            GrantRef {
+                domid: 0,
+                reference: 0
+            };
+            count as usize
+        ];
+        let mut request = MapGrantRef::write(refs.as_slice());
+        unsafe {
+            sys::map_grant_ref(self.handle.as_raw_fd(), request.as_mut_ptr())?;
+        };
+        let result =
+            MapGrantRef::read(refs.len() as u32, request).ok_or(Error::StructureReadFailed)?;
+        Ok((result.index, result.refs))
+    }
+
+    pub fn unmap_grant_ref(&self, index: u64, count: u32) -> Result<()> {
+        let mut request = UnmapGrantRef {
+            index,
+            count,
+            pad: 0,
+        };
+        unsafe {
+            sys::unmap_grant_ref(self.handle.as_raw_fd(), &mut request)?;
+        }
+        Ok(())
+    }
+
+    pub fn get_offset_for_vaddr(&self, vaddr: u64) -> Result<(u64, u32)> {
+        let mut request = GetOffsetForVaddr {
+            vaddr,
+            pad: 0,
+            offset: 0,
+            count: 0,
+        };
+        unsafe {
+            sys::get_offset_for_vaddr(self.handle.as_raw_fd(), &mut request)?;
+        }
+        Ok((request.offset, request.count))
+    }
+
+    pub fn set_max_grants(&self, count: u32) -> Result<()> {
+        let mut request = SetMaxGrants { count };
+        unsafe {
+            sys::set_max_grants(self.handle.as_raw_fd(), &mut request)?;
+        }
+        Ok(())
+    }
+
+    pub fn unmap_notify(&self, index: u64, send: bool, port: u32) -> Result<()> {
+        let mut request = UnmapNotify {
+            index,
+            action: if send {
+                UNMAP_NOTIFY_SEND_EVENT
+            } else {
+                UNMAP_NOTIFY_CLEAR_BYTE
+            },
+            port,
+        };
+        unsafe {
+            sys::unmap_notify(self.handle.as_raw_fd(), &mut request)?;
+        }
+        Ok(())
+    }
+}
+
+pub struct GrantAlloc {
+    handle: File,
+}
+
+impl GrantAlloc {
+    pub fn open() -> Result<GrantAlloc> {
+        let handle = OpenOptions::new()
+            .read(true)
+            .write(true)
+            .open("/dev/xen/gntalloc")?;
+        Ok(GrantAlloc { handle })
+    }
+
+    pub fn alloc_gref(&self, domid: u16, flags: u16, count: u32) -> Result<(u64, Vec<u32>)> {
+        let mut request = AllocGref::write(AllocGref {
+            domid,
+            flags,
+            count,
+        });
+        unsafe {
+            sys::alloc_gref(self.handle.as_raw_fd(), request.as_mut_ptr())?;
+        };
+        AllocGref::read(count, request).ok_or(Error::StructureReadFailed)
+    }
+
+    pub fn dealloc_gref(&self, index: u64, count: u32) -> Result<()> {
+        let mut request = DeallocGref { index, count };
+        unsafe {
+            sys::dealloc_gref(self.handle.as_raw_fd(), &mut request)?;
+        };
+        Ok(())
+    }
+
+    pub fn unmap_notify(&self, index: u64, send: bool, port: u32) -> Result<()> {
+        let mut request = UnmapNotify {
+            index,
+            action: if send {
+                UNMAP_NOTIFY_SEND_EVENT
+            } else {
+                UNMAP_NOTIFY_CLEAR_BYTE
+            },
+            port,
+        };
+        unsafe {
+            sys::unmap_notify(self.handle.as_raw_fd(), &mut request)?;
+        }
+        Ok(())
+    }
+}