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vm_memory: add GuestAddress::align

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Originally added on Windows. Allows us to get an aligned address from a
GuestAddress.

TEST=builds
BUG=b:213153154

Change-Id: I4bca6609f0fc2346598a52bd71f2ec60ac7f08f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3653425
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Noah Gold <nkgold@google.com>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
This commit is contained in:
Noah Gold 2022-05-18 22:13:25 -07:00 committed by Chromeos LUCI
parent 6f2996bdde
commit 6c291239af
1 changed files with 28 additions and 0 deletions
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28
vm_memory/src/guest_address.rs
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@ -55,6 +55,17 @@ impl GuestAddress {
pub fn mask(self, mask: u64) -> GuestAddress {
GuestAddress(self.0 & mask as u64)
}
/// Returns the next highest address that is a multiple of `align`, or an unchanged copy of the
/// address if it's already a multiple of `align`. Returns None on overflow.
///
/// `align` must be a power of 2.
pub fn align(self, align: u64) -> Option<GuestAddress> {
if align <= 1 {
return Some(self);
}
self.checked_add(align - 1).map(|a| a & !(align - 1))
}
}
impl BitAnd<u64> for GuestAddress {
@ -146,4 +157,21 @@ mod tests {
assert_eq!(Some(GuestAddress(0xffffffffffffff57)), a.checked_add(2));
assert!(a.checked_add(0xf0).is_none());
}
#[test]
fn align() {
assert_eq!(GuestAddress(12345).align(0), Some(GuestAddress(12345)));
assert_eq!(GuestAddress(12345).align(1), Some(GuestAddress(12345)));
assert_eq!(GuestAddress(12345).align(2), Some(GuestAddress(12346)));
assert_eq!(GuestAddress(0).align(4096), Some(GuestAddress(0)));
assert_eq!(GuestAddress(1).align(4096), Some(GuestAddress(4096)));
assert_eq!(GuestAddress(4095).align(4096), Some(GuestAddress(4096)));
assert_eq!(GuestAddress(4096).align(4096), Some(GuestAddress(4096)));
assert_eq!(GuestAddress(4097).align(4096), Some(GuestAddress(8192)));
assert_eq!(
GuestAddress(u64::MAX & !4095).align(4096),
Some(GuestAddress(u64::MAX & !4095)),
);
assert_eq!(GuestAddress(u64::MAX).align(2), None);
}
}