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guest_mem: Add support for guest memory access wrappers for PagedRanges #2444

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guest_mem: Add support for guest memory access wrappers for PagedRanges #2444

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ed9df2f
Removing the ide file
SrinivasShekar Nov 19, 2025
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Merge branch 'main' into guestMemAccessWrappers
SrinivasShekar Nov 19, 2025
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17 changes: 17 additions & 0 deletions vm/vmcore/guestmem/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1900,6 +1900,23 @@ impl GuestMemory {
})
}

/// Check if a given PagedRange is readable or not.
pub fn probe_gpn_readable_range(&self, range: &PagedRange<'_>) -> Result<(), GuestMemoryError> {
Comment on lines +1903 to +1904
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Copilot AI Nov 19, 2025

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[nitpick] The documentation could be more descriptive. Consider expanding it to clarify what "readable" means in this context and what errors might be returned. For example:

/// Checks if all pages in the given PagedRange are readable.
///
/// This probes each page in the range by attempting to read a single byte.
/// Returns an error if any page in the range is not accessible or is outside
/// the guest's physical address space.
///
/// # Errors
/// Returns `GuestMemoryError` if any page is inaccessible or invalid.
pub fn probe_gpn_readable_range(&self, range: &PagedRange<'_>) -> Result<(), GuestMemoryError>

The same applies to probe_gpn_writable_range.

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self.op_range(GuestMemoryOperation::Probe, range, move |addr, _r| {
let mut b = [0];
self.read_at_inner(addr, &mut b)
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@jstarks jstarks Nov 19, 2025

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Use read_plain_inner, it's more efficient.

})
}

/// Check if a given PagedRange is writable or not.
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Copilot AI Nov 19, 2025

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[nitpick] Consider adding similar documentation to probe_gpn_writable_range as suggested for probe_gpn_readable_range. The documentation should clarify that this checks writability by attempting a compare-exchange operation.

Suggested change
/// Check if a given PagedRange is writable or not.
/// Check if a given PagedRange is writable or not.
///
/// This checks writability by attempting a compare-exchange operation at each address in the range.
/// If the compare-exchange succeeds, the page is considered writable; otherwise, an error is returned.

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pub fn probe_gpn_writable_range(&self, range: &PagedRange<'_>) -> Result<(), GuestMemoryError> {
self.op_range(GuestMemoryOperation::Probe, range, move |addr, _r| {
self.compare_exchange(addr, 0u8, 0)
.map(|_| ())
.map_err(|err| GuestMemoryBackingError::other(addr, err))
})
}

/// Check if a given GPA is readable or not.
pub fn probe_gpa_readable(&self, gpa: u64) -> Result<(), GuestMemoryErrorKind> {
let mut b = [0];
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