diff options
Diffstat (limited to 'sys_util/src/guest_memory.rs')
| -rw-r--r-- | sys_util/src/guest_memory.rs | 140 |
1 files changed, 97 insertions, 43 deletions
diff --git a/sys_util/src/guest_memory.rs b/sys_util/src/guest_memory.rs index e8f620b..60b775a 100644 --- a/sys_util/src/guest_memory.rs +++ b/sys_util/src/guest_memory.rs @@ -7,6 +7,7 @@ use std::convert::AsRef; use std::convert::TryFrom; use std::fmt::{self, Display}; +use std::mem::size_of; use std::os::unix::io::{AsRawFd, RawFd}; use std::result; use std::sync::Arc; @@ -87,11 +88,19 @@ struct MemoryRegion { memfd_offset: u64, } -fn region_end(region: &MemoryRegion) -> GuestAddress { - // unchecked_add is safe as the region bounds were checked when it was created. - region - .guest_base - .unchecked_add(region.mapping.size() as u64) +impl MemoryRegion { + fn start(&self) -> GuestAddress { + self.guest_base + } + + fn end(&self) -> GuestAddress { + // unchecked_add is safe as the region bounds were checked when it was created. + self.guest_base.unchecked_add(self.mapping.size() as u64) + } + + fn contains(&self, addr: GuestAddress) -> bool { + addr >= self.guest_base && addr < self.end() + } } /// Tracks a memory region and where it is mapped in the guest, along with a shm @@ -200,8 +209,8 @@ impl GuestMemory { pub fn end_addr(&self) -> GuestAddress { self.regions .iter() - .max_by_key(|region| region.guest_base) - .map_or(GuestAddress(0), |region| region_end(region)) + .max_by_key(|region| region.start()) + .map_or(GuestAddress(0), MemoryRegion::end) } /// Returns the total size of memory in bytes. @@ -214,9 +223,7 @@ impl GuestMemory { /// Returns true if the given address is within the memory range available to the guest. pub fn address_in_range(&self, addr: GuestAddress) -> bool { - self.regions - .iter() - .any(|region| region.guest_base <= addr && addr < region_end(region)) + self.regions.iter().any(|region| region.contains(addr)) } /// Returns true if the given range (start, end) is overlap with the memory range @@ -224,7 +231,7 @@ impl GuestMemory { pub fn range_overlap(&self, start: GuestAddress, end: GuestAddress) -> bool { self.regions .iter() - .any(|region| region.guest_base < end && start < region_end(region)) + .any(|region| region.start() < end && start < region.end()) } /// Returns the address plus the offset if it is in range. @@ -267,7 +274,7 @@ impl GuestMemory { for (index, region) in self.regions.iter().enumerate() { cb( index, - region.guest_base, + region.start(), region.mapping.size(), region.mapping.as_ptr() as usize, region.memfd_offset, @@ -442,6 +449,61 @@ impl GuestMemory { }) } + /// Returns a `VolatileSlice` of `len` bytes starting at `addr`. Returns an error if the slice + /// is not a subset of this `GuestMemory`. + /// + /// # Examples + /// * Write `99` to 30 bytes starting at guest address 0x1010. + /// + /// ``` + /// # use sys_util::{GuestAddress, GuestMemory, GuestMemoryError, MemoryMapping}; + /// # fn test_volatile_slice() -> Result<(), GuestMemoryError> { + /// # let start_addr = GuestAddress(0x1000); + /// # let mut gm = GuestMemory::new(&vec![(start_addr, 0x400)])?; + /// let vslice = gm.get_slice_at_addr(GuestAddress(0x1010), 30)?; + /// vslice.write_bytes(99); + /// # Ok(()) + /// # } + /// ``` + pub fn get_slice_at_addr(&self, addr: GuestAddress, len: usize) -> Result<VolatileSlice> { + self.regions + .iter() + .find(|region| region.contains(addr)) + .ok_or(Error::InvalidGuestAddress(addr)) + .and_then(|region| { + // The cast to a usize is safe here because we know that `region.contains(addr)` and + // it's not possible for a memory region to be larger than what fits in a usize. + region + .mapping + .get_slice(addr.offset_from(region.start()) as usize, len) + .map_err(Error::VolatileMemoryAccess) + }) + } + + /// Returns a `VolatileRef` to an object at `addr`. Returns Ok(()) if the object fits, or Err if + /// it extends past the end. + /// + /// # Examples + /// * Get a &u64 at offset 0x1010. + /// + /// ``` + /// # use sys_util::{GuestAddress, GuestMemory, GuestMemoryError, MemoryMapping}; + /// # fn test_ref_u64() -> Result<(), GuestMemoryError> { + /// # let start_addr = GuestAddress(0x1000); + /// # let mut gm = GuestMemory::new(&vec![(start_addr, 0x400)])?; + /// gm.write_obj_at_addr(47u64, GuestAddress(0x1010))?; + /// let vref = gm.get_ref_at_addr::<u64>(GuestAddress(0x1010))?; + /// assert_eq!(vref.load(), 47u64); + /// # Ok(()) + /// # } + /// ``` + pub fn get_ref_at_addr<T: DataInit>(&self, addr: GuestAddress) -> Result<VolatileRef<T>> { + let buf = self.get_slice_at_addr(addr, size_of::<T>())?; + // Safe because we have know that `buf` is at least `size_of::<T>()` bytes and that the + // returned reference will not outlive this `GuestMemory`. + Ok(unsafe { VolatileRef::new(buf.as_mut_ptr() as *mut T) }) + } + /// Reads data from a file descriptor and writes it to guest memory. /// /// # Arguments @@ -550,15 +612,16 @@ impl GuestMemory { where F: FnOnce(&MemoryMapping, usize) -> Result<T>, { - for region in self.regions.iter() { - if guest_addr >= region.guest_base && guest_addr < region_end(region) { - return cb( + self.regions + .iter() + .find(|region| region.contains(guest_addr)) + .ok_or(Error::InvalidGuestAddress(guest_addr)) + .and_then(|region| { + cb( ®ion.mapping, - guest_addr.offset_from(region.guest_base) as usize, - ); - } - } - Err(Error::InvalidGuestAddress(guest_addr)) + guest_addr.offset_from(region.start()) as usize, + ) + }) } /// Convert a GuestAddress into an offset within self.memfd. @@ -585,25 +648,11 @@ impl GuestMemory { /// assert_eq!(offset, 0x3500); /// ``` pub fn offset_from_base(&self, guest_addr: GuestAddress) -> Result<u64> { - for region in self.regions.iter() { - if guest_addr >= region.guest_base && guest_addr < region_end(region) { - return Ok(region.memfd_offset + guest_addr.offset_from(region.guest_base) as u64); - } - } - Err(Error::InvalidGuestAddress(guest_addr)) - } -} - -impl VolatileMemory for GuestMemory { - fn get_slice(&self, offset: u64, count: u64) -> VolatileMemoryResult<VolatileSlice> { - for region in self.regions.iter() { - if offset >= region.guest_base.0 && offset < region_end(region).0 { - return region - .mapping - .get_slice(offset - region.guest_base.0, count); - } - } - Err(VolatileMemoryError::OutOfBounds { addr: offset }) + self.regions + .iter() + .find(|region| region.contains(guest_addr)) + .ok_or(Error::InvalidGuestAddress(guest_addr)) + .map(|region| region.memfd_offset + guest_addr.offset_from(region.start())) } } @@ -690,8 +739,11 @@ mod tests { gm.write_obj_at_addr(val1, GuestAddress(0x500)).unwrap(); gm.write_obj_at_addr(val2, GuestAddress(0x1000 + 32)) .unwrap(); - let num1: u64 = gm.get_ref(0x500).unwrap().load(); - let num2: u64 = gm.get_ref(0x1000 + 32).unwrap().load(); + let num1: u64 = gm.get_ref_at_addr(GuestAddress(0x500)).unwrap().load(); + let num2: u64 = gm + .get_ref_at_addr(GuestAddress(0x1000 + 32)) + .unwrap() + .load(); assert_eq!(val1, num1); assert_eq!(val2, num2); } @@ -704,8 +756,10 @@ mod tests { let val1: u64 = 0xaa55aa55aa55aa55; let val2: u64 = 0x55aa55aa55aa55aa; - gm.get_ref(0x500).unwrap().store(val1); - gm.get_ref(0x1000 + 32).unwrap().store(val2); + gm.get_ref_at_addr(GuestAddress(0x500)).unwrap().store(val1); + gm.get_ref_at_addr(GuestAddress(0x1000 + 32)) + .unwrap() + .store(val2); let num1: u64 = gm.read_obj_from_addr(GuestAddress(0x500)).unwrap(); let num2: u64 = gm.read_obj_from_addr(GuestAddress(0x1000 + 32)).unwrap(); assert_eq!(val1, num1); |