diff --git a/resources/src/address_allocator.rs b/resources/src/address_allocator.rs
index 9d8b28d7ae..04fe63e06a 100644
--- a/resources/src/address_allocator.rs
+++ b/resources/src/address_allocator.rs
@@ -62,15 +62,13 @@ impl AddressAllocator {
         })
     }
 
-    /// Allocates a range of addresses from the managed region with an optional tag
-    /// and minimal alignment. Returns allocated_address. (allocated_address, size, tag)
-    /// can be retrieved through the `get` method.
-    pub fn allocate_with_align(
+    fn internal_allocate_with_align(
         &mut self,
         size: u64,
         alloc: Alloc,
         tag: String,
         alignment: u64,
+        reverse: bool,
     ) -> Result<u64> {
         let alignment = cmp::max(self.alignment, alignment);
 
@@ -84,24 +82,42 @@ impl AddressAllocator {
             return Err(Error::BadAlignment);
         }
 
-        // finds first region matching alignment and size.
-        match self
-            .regions
-            .iter()
-            .find(|range| {
-                match range.0 % alignment {
-                    0 => range.0.checked_add(size - 1),
-                    r => range.0.checked_add(size - 1 + alignment - r),
-                }
-                .map_or(false, |end| end <= range.1)
-            })
-            .cloned()
-        {
+        let region = if !reverse {
+            // finds first region matching alignment and size.
+            self.regions
+                .iter()
+                .find(|range| {
+                    match range.0 % alignment {
+                        0 => range.0.checked_add(size - 1),
+                        r => range.0.checked_add(size - 1 + alignment - r),
+                    }
+                    .map_or(false, |end| end <= range.1)
+                })
+                .cloned()
+        } else {
+            // finds last region matching alignment and size.
+            self.regions
+                .iter()
+                .rev()
+                .find(|range| {
+                    range
+                        .1
+                        .checked_sub(size - 1)
+                        .map_or(false, |start| start & !(alignment - 1) >= range.0)
+                })
+                .cloned()
+        };
+
+        match region {
             Some(slot) => {
                 self.regions.remove(&slot);
-                let start = match slot.0 % alignment {
-                    0 => slot.0,
-                    r => slot.0 + alignment - r,
+                let start = if !reverse {
+                    match slot.0 % alignment {
+                        0 => slot.0,
+                        r => slot.0 + alignment - r,
+                    }
+                } else {
+                    (slot.1 - (size - 1)) & !(alignment - 1)
                 };
                 let end = start + size - 1;
                 if slot.0 < start {
@@ -118,6 +134,32 @@ impl AddressAllocator {
         }
     }
 
+    /// Allocates a range of addresses from the reverse managed region with an optional tag
+    /// and minimal alignment. Returns allocated_address. (allocated_address, size, tag)
+    /// can be retrieved through the `get` method.
+    pub fn reverse_allocate_with_align(
+        &mut self,
+        size: u64,
+        alloc: Alloc,
+        tag: String,
+        alignment: u64,
+    ) -> Result<u64> {
+        self.internal_allocate_with_align(size, alloc, tag, alignment, true)
+    }
+
+    /// Allocates a range of addresses from the managed region with an optional tag
+    /// and minimal alignment. Returns allocated_address. (allocated_address, size, tag)
+    /// can be retrieved through the `get` method.
+    pub fn allocate_with_align(
+        &mut self,
+        size: u64,
+        alloc: Alloc,
+        tag: String,
+        alignment: u64,
+    ) -> Result<u64> {
+        self.internal_allocate_with_align(size, alloc, tag, alignment, false)
+    }
+
     pub fn allocate(&mut self, size: u64, alloc: Alloc, tag: String) -> Result<u64> {
         self.allocate_with_align(size, alloc, tag, self.alignment)
     }
diff --git a/src/linux.rs b/src/linux.rs
index f5782e70e4..442d9be311 100644
--- a/src/linux.rs
+++ b/src/linux.rs
@@ -1157,7 +1157,7 @@ fn create_pmem_device(
 
     let mapping_address = resources
         .mmio_allocator(MmioType::High)
-        .allocate_with_align(
+        .reverse_allocate_with_align(
             arena_size,
             Alloc::PmemDevice(index),
             format!("pmem_disk_image_{}", index),
diff --git a/x86_64/src/lib.rs b/x86_64/src/lib.rs
index 6a7f2f69fb..cc61eaf497 100644
--- a/x86_64/src/lib.rs
+++ b/x86_64/src/lib.rs
@@ -362,7 +362,7 @@ impl arch::LinuxArch for X8664arch {
         SystemAllocator::builder()
             .add_io_addresses(0xc000, 0x10000)
             .add_low_mmio_addresses(END_ADDR_BEFORE_32BITS, MMIO_SIZE)
-            .add_high_mmio_addresses(high_mmio_start, u64::max_value() - high_mmio_start)
+            .add_high_mmio_addresses(high_mmio_start, Self::get_phys_max_addr() - high_mmio_start)
             .create_allocator(X86_64_IRQ_BASE)
             .unwrap()
     }