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fix: support guest writes across contiguous mappings #22

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fix: support guest writes across contiguous mappings #22

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49 changes: 44 additions & 5 deletions src/nodes/lib/syscall/src/utils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,12 +22,51 @@ pub fn align_down(value: u64, align: u64) -> u64 {
pub fn guest_range(addr: u64, len: usize, mem_len: usize) -> Option<usize> {
let end = addr.checked_add(len as u64)?;
let mappings = GUEST_MAPPINGS.lock().ok()?;
for mapping in mappings.iter().rev() {
let map_end = mapping.virt.checked_add(mapping.len)?;
if addr < mapping.virt || end > map_end {
continue;
if len == 0 {
if let Some(mapping) = mappings.iter().rev().find(|mapping| {
mapping
.virt
.checked_add(mapping.len)
.is_some_and(|map_end| addr >= mapping.virt && addr < map_end)
}) {
let phys = mapping.phys.checked_add(addr.checked_sub(mapping.virt)?)?;
if phys < GUEST_MEM_BASE {
return None;
}
let offset = phys.checked_sub(GUEST_MEM_BASE)? as usize;
return (offset <= mem_len).then_some(offset);
}
let phys = mapping.phys.checked_add(addr - mapping.virt)?;
}
if mappings.iter().rev().any(|mapping| {
mapping
.virt
.checked_add(mapping.len)
.is_some_and(|map_end| addr >= mapping.virt && addr < map_end)
}) {
let mut cursor = addr;
let mut remaining = len as u64;
let mut phys_start: Option<u64> = None;
while remaining != 0 {
let mapping = mappings.iter().rev().find(|mapping| {
mapping
.virt
.checked_add(mapping.len)
.is_some_and(|map_end| cursor >= mapping.virt && cursor < map_end)
})?;
let map_offset = cursor.checked_sub(mapping.virt)?;
let phys = mapping.phys.checked_add(map_offset)?;
if let Some(start) = phys_start {
if phys != start.checked_add(cursor.checked_sub(addr)?)? {
return None;
}
} else {
phys_start = Some(phys);
}
let chunk = remaining.min(mapping.len.checked_sub(map_offset)?);
cursor = cursor.checked_add(chunk)?;
remaining -= chunk;
}
let phys = phys_start?;
if phys < GUEST_MEM_BASE {
return None;
}
Expand Down