lkml.org 
[lkml]   [2022]   [Jul]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.18 04/61] x86/entry: Dont call error_entry() for XENPV
    Date
    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
    @@ -336,8 +336,17 @@ 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


    \
     
     \ /
      Last update: 2022-07-12 21:08    [W:2.254 / U:0.032 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site