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x86/entry: Don't call error_entry() for XENPV

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commit 64cbd0acb58203fb769ed2f4eab526d43e243847 upstream.

XENPV guests enter already on the task stack and they can't fault for
native_iret() nor native_load_gs_index() since they use their own pvop
for IRET and load_gs_index(). A CR3 switch is not needed either.

So there is no reason to call error_entry() in XENPV.

  [ bp: Massage commit message. ]

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220503032107.680190-6-jiangshanlai@gmail.com
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lai Jiangshan 2022-05-03 11:21:06 +08:00 committed by Greg Kroah-Hartman
parent cac414684b
commit 1fd333eb33
1 changed files with 11 additions and 2 deletions
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13
arch/x86/entry/entry_64.S
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@ -333,8 +333,17 @@ SYM_CODE_END(push_and_clear_regs)
call push_and_clear_regs
UNWIND_HINT_REGS
call error_entry
movq %rax, %rsp /* switch to the task stack if from userspace */
/*
* Call error_entry() and switch to the task stack if from userspace.
*
* When in XENPV, it is already in the task stack, and it can't fault
* for native_iret() nor native_load_gs_index() since XENPV uses its
* own pvops for IRET and load_gs_index(). And it doesn't need to
* switch the CR3. So it can skip invoking error_entry().
*/
ALTERNATIVE "call error_entry; movq %rax, %rsp", \
"", X86_FEATURE_XENPV
ENCODE_FRAME_POINTER
UNWIND_HINT_REGS