diff options
| -rw-r--r-- | OvmfPkg/TdxDxe/X64/ApRunLoop.nasm | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/OvmfPkg/TdxDxe/X64/ApRunLoop.nasm b/OvmfPkg/TdxDxe/X64/ApRunLoop.nasm index 0bef89c485..57560015f4 100644 --- a/OvmfPkg/TdxDxe/X64/ApRunLoop.nasm +++ b/OvmfPkg/TdxDxe/X64/ApRunLoop.nasm @@ -20,7 +20,7 @@ SECTION .text BITS 64
-%define TDVMCALL_EXPOSE_REGS_MASK 0xffec
+%define TDVMCALL_EXPOSE_REGS_MASK 0xffcc
%define TDVMCALL 0x0
%define EXIT_REASON_CPUID 0xa
@@ -28,6 +28,30 @@ BITS 64 db 0x66, 0x0f, 0x01, 0xcc
%endmacro
+%macro tdcall_regs_preamble 2
+ mov rax, %1
+
+ xor rcx, rcx
+ mov ecx, %2
+
+ ; R10 = 0 (standard TDVMCALL)
+
+ xor r10d, r10d
+
+ ; Zero out unused (for standard TDVMCALL) registers to avoid leaking
+ ; secrets to the VMM.
+
+ xor esi, esi
+ xor edi, edi
+
+ xor edx, edx
+ xor ebp, ebp
+ xor r8d, r8d
+ xor r9d, r9d
+ xor r14, r14
+ xor r15, r15
+%endmacro
+
;
; Relocated Ap Mailbox loop
;
@@ -40,11 +64,9 @@ global ASM_PFX(AsmRelocateApMailBoxLoop) ASM_PFX(AsmRelocateApMailBoxLoop):
AsmRelocateApMailBoxLoopStart:
- mov rax, TDVMCALL
- mov rcx, TDVMCALL_EXPOSE_REGS_MASK
- xor r10, r10
mov r11, EXIT_REASON_CPUID
mov r12, 0xb
+ tdcall_regs_preamble TDVMCALL, TDVMCALL_EXPOSE_REGS_MASK
tdcall
test r10, r10
jnz Panic
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