kernel: migrate page tables to paging crate

Replace the kernel-local page table implementation with wrappers around the generic paging crate. Add the SvsmPaging adapter for allocation, address conversion, feature masks, and self-map index configuration while preserving the kernel-facing PageTable and PageTablePart APIs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Signed-off-by: Ziqiao Zhou <ziqiaozhou@microsoft.com>

Author: ziqiaozhou

kernel/src/error.rs

@@ -38,6 +38,7 @@ use crate::virtio::VirtioError;
 #[cfg(feature = "vsock")]
 use crate::vsock::VsockError;
 use elf::ElfError;
+use paging::traits::PagingError;
 use syscall::SysCallError;
 
 /// Errors related to I/O operations.
@@ -160,6 +161,8 @@ pub enum SvsmError {
     TeeAttestation(AttestationError),
     /// Errors related to ImmutAfterInitCell
     ImmutAfterInit(ImmutAfterInitError),
+    /// Errors from the paging crate
+    Paging(PagingError),
     /// Errors related to vsock.
     #[cfg(feature = "vsock")]
     Vsock(VsockError),
@@ -179,6 +182,12 @@ impl From<ElfError> for SvsmError {
     }
 }
 
+impl From<PagingError> for SvsmError {
+    fn from(err: PagingError) -> Self {
+        Self::Paging(err)
+    }
+}
+
 impl From<ApicError> for SvsmError {
     fn from(err: ApicError) -> Self {
         Self::Apic(err)