Messages in this thread | | | Date | Wed, 20 Apr 2022 18:32:43 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH V5 5/7] x86/entry: Don't call error_entry() for XENPV |
| |
On Tue, Apr 12, 2022 at 08:15:39PM +0800, Lai Jiangshan wrote: > From: Lai Jiangshan <jiangshan.ljs@antgroup.com> > > 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 there is no reason to call error_entry() in XENPV. > > Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com> > --- > arch/x86/entry/entry_64.S | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S > index 7b6a0f15bb20..3aca7815fe79 100644 > --- a/arch/x86/entry/entry_64.S > +++ b/arch/x86/entry/entry_64.S > @@ -328,8 +328,17 @@ SYM_CODE_END(ret_from_fork) > PUSH_AND_CLEAR_REGS > ENCODE_FRAME_POINTER > > - 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 > > --
This one needs Jürgen. CCed.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
| |