init template of EPT violation handler

Signed-off-by: smallkirby <[email protected]>

ymir/arch/x86/vmx.zig

@@ -128,6 +128,11 @@ pub const Vcpu = struct {
     /// Handle the VM-exit.
     fn handleExit(_: *Self, exit_info: ExitInformation) VmxError!void {
         switch (exit_info.basic_reason) {
+            .ept => {
+                const qual = try getExitQual(ext.QualEptViolation);
+                log.err("EPT violation: {?}", .{qual});
+                @panic("Aborting Ymir...");
+            },
             else => {
                 log.err("Unhandled VM-exit: reason={?}", .{exit_info.basic_reason});
                 @panic("Aborting Ymir...");
@@ -688,6 +693,11 @@ pub fn getExitReason() VmxError!ExitInformation {
     return @bitCast(@as(u32, @truncate(try vmread(vmcs.Ro.vmexit_reason))));
 }
 
+/// Get a VM-exit qualification from VMCS.
+fn getExitQual(T: anytype) VmxError!T {
+    return @bitCast(@as(u64, try vmread(vmcs.Ro.exit_qual)));
+}
+
 const VmxonRegion = packed struct {
     vmcs_revision_id: u31,
     zero: u1 = 0,

ymir/arch/x86/vmx/ept.zig

@@ -39,10 +39,13 @@ const num_table_entries: usize = 512;
 
 /// Init guest EPT.
 pub fn initEpt(
+    /// Guest physical address to map.
     guest_start: Phys,
+    /// Host physical address to map.
     host_start: Phys,
+    /// Size in bytes of the memory region to map.
     size: usize,
-    /// Page allocator that returns physical pages.
+    /// Page allocator.
     page_allocator: Allocator,
 ) ![]Lv4EptEntry {
     if (size & page_mask_2mb != 0) {

ymir/arch/x86/vmx/exit.zig

@@ -39,3 +39,45 @@ pub const QualIo = packed struct(u64) {
         imm = 1,
     };
 };
+
+/// Exit qualification for EPT violations.
+/// cf. SDM Vol.3C Table 28-7.
+pub const QualEptViolation = packed struct(u64) {
+    /// The violation was data read.
+    read: bool,
+    /// The violation was data write.
+    write: bool,
+    /// The violation was instruction fetch.
+    fetch: bool,
+    /// The page is readable.
+    readable: bool,
+    /// The page is writable.
+    writable: bool,
+    /// The page is executable.
+    executable: bool,
+    /// The page is executable for user-mode linear addresses.
+    /// Undefined if "mode-based execute control" is 0.
+    executable_user: bool,
+    /// Guest linear-address field is valid.
+    valid_linear: bool,
+    /// The violation occurred during a guest page table walk.
+    during_walk: bool,
+    ///
+    linear_user: bool,
+    ///
+    rw: bool,
+    ///
+    exec_disabled: bool,
+    ///
+    nmi_unblocking: bool,
+    ///
+    shadow_stack: bool,
+    ///
+    b60: bool,
+    ///
+    verification: bool,
+    ///
+    trace: bool,
+    /// Reserved.
+    reserved: u47,
+};