From: Lai Jiangshan jiangshan.ljs@antgroup.com
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 --- arch/x86/entry/entry_64.S | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
--- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -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