Define a new variable header type for environment information (#18)

The IGVM_VHT_ENVIRONMENT_INFO_PARAMETER defines a bitfield that permits the hosting environment to describe certain behaviors so the VM can conform. The only currently defined behavior indicates whether the default state of memory is assigned (private) or unassigned (shared) so the VM knows whether it must request page state changes before using any memory. Other behaviors will be defined in the future.
microsoft · Dec 13, 2023 · 2a6e996 · 2a6e996
1 parent 4977f88
commit 2a6e996
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Showing 2 changed files with 48 additions and 16 deletions.
diff --git a/igvm/src/lib.rs b/igvm/src/lib.rs
@@ -555,6 +555,7 @@ pub enum IgvmDirectiveHeader {
         initial_data: Vec<u8>,
     },
     VpCount(IGVM_VHS_PARAMETER),
+    EnvironmentInfo(IGVM_VHS_PARAMETER),
     Srat(IGVM_VHS_PARAMETER),
     Madt(IGVM_VHS_PARAMETER),
     Slit(IGVM_VHS_PARAMETER),
@@ -815,6 +816,7 @@ impl IgvmDirectiveHeader {
             IgvmDirectiveHeader::PageData { .. } => size_of::<IGVM_VHS_PAGE_DATA>(),
             IgvmDirectiveHeader::ParameterArea { .. } => size_of::<IGVM_VHS_PARAMETER_AREA>(),
             IgvmDirectiveHeader::VpCount(param) => size_of_val(param),
+            IgvmDirectiveHeader::EnvironmentInfo(param) => size_of_val(param),
             IgvmDirectiveHeader::Srat(param) => size_of_val(param),
             IgvmDirectiveHeader::Madt(param) => size_of_val(param),
             IgvmDirectiveHeader::Slit(param) => size_of_val(param),
@@ -931,6 +933,13 @@ impl IgvmDirectiveHeader {
                     variable_headers,
                 );
             }
+            IgvmDirectiveHeader::EnvironmentInfo(param) => {
+                append_header(
+                    param,
+                    IgvmVariableHeaderType::IGVM_VHT_ENVIRONMENT_INFO_PARAMETER,
+                    variable_headers,
+                );
+            }
             IgvmDirectiveHeader::Srat(param) => {
                 append_header(
                     param,
@@ -1175,6 +1184,7 @@ impl IgvmDirectiveHeader {
             } => Some(*compatibility_mask),
             ParameterArea { .. } => None,
             VpCount(_) => None,
+            EnvironmentInfo(_) => None,
             Srat(_) => None,
             Madt(_) => None,
             Slit(_) => None,
@@ -1219,6 +1229,7 @@ impl IgvmDirectiveHeader {
             } => Some(compatibility_mask),
             ParameterArea { .. } => None,
             VpCount(_) => None,
+            EnvironmentInfo(_) => None,
             Srat(_) => None,
             Madt(_) => None,
             Slit(_) => None,
@@ -1347,6 +1358,7 @@ impl IgvmDirectiveHeader {
             // Parameter usage is validated by the IgvmFile functions, as more
             // info is needed than just this header.
             IgvmDirectiveHeader::VpCount(_)
+            | IgvmDirectiveHeader::EnvironmentInfo(_)
             | IgvmDirectiveHeader::Srat(_)
             | IgvmDirectiveHeader::Madt(_)
             | IgvmDirectiveHeader::Slit(_)
@@ -1637,6 +1649,11 @@ impl IgvmDirectiveHeader {
             {
                 IgvmDirectiveHeader::VpCount(read_header(&mut variable_headers)?)
             }
+            IgvmVariableHeaderType::IGVM_VHT_ENVIRONMENT_INFO_PARAMETER
+                if length == size_of::<IGVM_VHS_PARAMETER>() =>
+            {
+                IgvmDirectiveHeader::EnvironmentInfo(read_header(&mut variable_headers)?)
+            }
             IgvmVariableHeaderType::IGVM_VHT_SRAT if length == size_of::<IGVM_VHS_PARAMETER>() => {
                 IgvmDirectiveHeader::Srat(read_header(&mut variable_headers)?)
             }
@@ -2248,6 +2265,7 @@ impl IgvmFile {
                     }
                 }
                 IgvmDirectiveHeader::VpCount(info)
+                | IgvmDirectiveHeader::EnvironmentInfo(info)
                 | IgvmDirectiveHeader::Srat(info)
                 | IgvmDirectiveHeader::Madt(info)
                 | IgvmDirectiveHeader::Slit(info)
@@ -3002,8 +3020,16 @@ impl IgvmFile {
                         }
                     }
                 }
-                VpCount(info) | Srat(info) | Madt(info) | Slit(info) | Pptt(info)
-                | MmioRanges(info) | MemoryMap(info) | CommandLine(info) | DeviceTree(info) => {
+                VpCount(info)
+                | EnvironmentInfo(info)
+                | Srat(info)
+                | Madt(info)
+                | Slit(info)
+                | Pptt(info)
+                | MmioRanges(info)
+                | MemoryMap(info)
+                | CommandLine(info)
+                | DeviceTree(info) => {
                     fixup_parameter_index(
                         &mut info.parameter_area_index,
                         &fixup_parameter_index_map,
@@ -3911,6 +3937,11 @@ mod tests {
         IgvmVariableHeaderType::IGVM_VHT_VP_COUNT_PARAMETER
     ));
 
+    test_igvm_parameter!(test_environment_info(
+        IgvmDirectiveHeader::EnvironmentInfo,
+        IgvmVariableHeaderType::IGVM_VHT_ENVIRONMENT_INFO_PARAMETER
+    ));
+
     test_igvm_parameter!(test_srat(
         IgvmDirectiveHeader::Srat,
         IgvmVariableHeaderType::IGVM_VHT_SRAT

diff --git a/igvm_defs/src/lib.rs b/igvm_defs/src/lib.rs
@@ -331,13 +331,13 @@ pub enum IgvmVariableHeaderType {
     ///
     /// IGVM specific extensions can be found in the [`dt`] module.
     IGVM_VHT_DEVICE_TREE = 0x312,
-    /// A parameter which holds a 4-byte u32 value defining the default state
-    /// of memory in the memory map.  The value is defined by the
-    /// IgvmMemoryState enumeration.  The loader will write the state to the
-    /// specified offset of the specified parameter area.  The parameter
-    /// location information is specified by a structure of type
-    /// [`IGVM_VHS_PARAMETER`].
-    IGVM_VHT_MEMORY_STATE_PARAMETER = 0x313,
+    /// A parameter which holds a u32 bitfield value defining environmental
+    /// state of the VM.  The bitfield is defined by the `IgvmEnvironmentInfo`
+    /// structure.  The loader will write the state to the specified offset of
+    /// the specified parameter area.  The parameter location information is
+    /// specified by a structure of type [`IGVM_VHS_PARAMETER`].
+    #[cfg_attr(docsrs, doc(cfg(feature = "unstable")))]
+    IGVM_VHT_ENVIRONMENT_INFO_PARAMETER = 0x313,
 }
 
 /// The range of header types for platform structures.
@@ -637,14 +637,15 @@ pub struct IGVM_VHS_PARAMETER_AREA {
 
 /// Default memory state described by the IGVM_VHT_MEMORY_STATE_PARAMETER
 /// parameter.
-#[open_enum]
-#[derive(AsBytes, FromBytes, FromZeroes, Debug, Clone, Copy, PartialEq, Eq)]
-#[repr(u32)]
-pub enum IgvmMemoryState {
-    /// Default state of memory is assigned to the guest (private)
-    ASSIGNED = 0x0,
+#[cfg(feature = "unstable")]
+#[cfg_attr(docsrs, doc(cfg(feature = "unstable")))]
+#[bitfield(u32)]
+#[derive(AsBytes, FromBytes, FromZeroes, PartialEq, Eq)]
+pub struct IgvmEnvironmentInfo {
     /// Default state of memory is not assigned to the guest (shared)
-    UNASSIGNED = 0x1,
+    pub memory_is_shared: bool,
+    #[bits(31)]
+    pub reserved: u32,
 }
 
 /// Page data types that describe the type of import for