This is a note to let you know that I've just added the patch titled
x86/tdx: Skip saving output regs when SEAMCALL fails with VMFailInvalid
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-tdx-skip-saving-output-regs-when-seamcall-fails-.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8a83345f43e085807cb63237221cbd3ec18f8bef
Author: Kai Huang <kai.huang@xxxxxxxxx>
Date: Tue Aug 15 23:01:56 2023 +1200
x86/tdx: Skip saving output regs when SEAMCALL fails with VMFailInvalid
[ Upstream commit 03a423d40cb30e0e1cb77a801acb56ddb0bf6f5e ]
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@xxxxxxxxxxxxx>
Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/704088f5b4d72c7e24084f7f15bd1ac5005b7213.1692096753.git.kai.huang%40intel.com
Stable-dep-of: f65aa0ad79fc ("x86/tdx: Dynamically disable SEPT violations from causing #VEs")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/coco/tdx/tdcall.S b/arch/x86/coco/tdx/tdcall.S
index 2eca5f43734fe..e5d4b7d8ecd4a 100644
--- a/arch/x86/coco/tdx/tdcall.S
+++ b/arch/x86/coco/tdx/tdcall.S
@@ -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)
/*
diff --git a/arch/x86/virt/vmx/tdx/tdxcall.S b/arch/x86/virt/vmx/tdx/tdxcall.S
index 49a54356ae992..6bdf6e1379534 100644
--- a/arch/x86/virt/vmx/tdx/tdxcall.S
+++ b/arch/x86/virt/vmx/tdx/tdxcall.S
@@ -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
