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x86/tdx: Skip saving output regs when SEAMCALL fails with VMFailInvalid

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If SEAMCALL fails with VMFailInvalid, the SEAM software (e.g., the TDX
module) won't have chance to set any output register.  Skip saving the
output registers to the structure in this case.

Also, as '.Lno_output_struct' is the very last symbol before RET, rename
it to '.Lout' to make it short.

Opportunistically make the asm directives unindented.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/704088f5b4d72c7e24084f7f15bd1ac5005b7213.1692096753.git.kai.huang%40intel.com
This commit is contained in:
Kai Huang 2023-08-15 23:01:56 +12:00 committed by Dave Hansen
parent 5d092b6611
commit 03a423d40c
2 changed files with 20 additions and 12 deletions
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3
arch/x86/coco/tdx/tdcall.S
View File

@ -78,10 +78,7 @@
* Return status of TDCALL via RAX.
*/
SYM_FUNC_START(__tdx_module_call)
FRAME_BEGIN
TDX_MODULE_CALL host=0
FRAME_END
RET
SYM_FUNC_END(__tdx_module_call)
/*

29
arch/x86/virt/vmx/tdx/tdxcall.S
View File

@ -1,5 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0 */
#include <asm/asm-offsets.h>
#include <asm/frame.h>
#include <asm/tdx.h>
/*
@ -18,6 +19,7 @@
* TDX module.
*/
.macro TDX_MODULE_CALL host:req
FRAME_BEGIN
/*
* R12 will be used as temporary storage for struct tdx_module_output
* pointer. Since R12-R15 registers are not used by TDCALL/SEAMCALL
@ -44,7 +46,7 @@
mov %rsi, %rcx
/* Leave input param 2 in RDX */
.if \host
.if \host
seamcall
/*
* SEAMCALL instruction is essentially a VMExit from VMX root
@ -57,13 +59,10 @@
* This value will never be used as actual SEAMCALL error code as
* it is from the Reserved status code class.
*/
jnc .Lno_vmfailinvalid
mov $TDX_SEAMCALL_VMFAILINVALID, %rax
.Lno_vmfailinvalid:
.else
jc .Lseamcall_vmfailinvalid
.else
tdcall
.endif
.endif
/*
* Fetch output pointer from stack to R12 (It is used
@ -80,7 +79,7 @@
* Other registers may contain details of the failure.
*/
test %r12, %r12
jz .Lno_output_struct
jz .Lout
/* Copy result registers to output struct: */
movq %rcx, TDX_MODULE_rcx(%r12)
@ -90,7 +89,19 @@
movq %r10, TDX_MODULE_r10(%r12)
movq %r11, TDX_MODULE_r11(%r12)
.Lno_output_struct:
.Lout:
/* Restore the state of R12 register */
pop %r12
FRAME_END
RET
.if \host
.Lseamcall_vmfailinvalid:
mov $TDX_SEAMCALL_VMFAILINVALID, %rax
/* pop the unused output pointer back to %r9 */
pop %r9
jmp .Lout
.endif /* \host */
.endm