plat/kvm/x86: Add UEFI entry stub

Implements the small x86 specific UEFI entry point which will call
the early self relocator, adjust the initially unaligned stack and
finally jump to the architecture generic EFI stub.

Signed-off-by: Sergiu Moga <sergiu.moga@protonmail.com>
Reviewed-by: Michalis Pappas <michalis@unikraft.io>
Approved-by: Razvan Deaconescu <razvand@unikraft.io>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Closes: #909

diff --git a/plat/kvm/x86/efi_entry64.S b/plat/kvm/x86/efi_entry64.S
new file mode 100644 (file)
index 0000000..4e184d3
--- /dev/null
+++ b/plat/kvm/x86/efi_entry64.S
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/* Copyright (c) 2023, Unikraft GmbH and The Unikraft Authors.
+ * Licensed under the BSD-3-Clause License (the "License").
+ * You may not use this file except in compliance with the License.
+ */
+#include <uk/config.h>
+#include <uk/asm.h>
+
+.section .text
+ENTRY(uk_efi_entry64)
+       /* EFI gives us a stack misaligned by 8 */
+       and     $~0xf, %rsp
+
+       xorq    %rdi, %rdi
+       xorq    %rsi, %rsi
+       pushq   %rdx
+       pushq   %rcx
+       call    do_uk_reloc
+       popq    %rcx
+       popq    %rdx
+
+       call    uk_efi_main
+
+uk_efi_fail:
+       hlt
+       jmp     uk_efi_fail
+END(uk_efi_entry64)