The following commit has been merged into the x86/boot branch of tip: Commit-ID: 9e5683e2d0b5584c51993908c5d0afa78e613492 Gitweb: https://git.kernel.org/tip/9e5683e2d0b5584c51993908c5d0afa78e613492 Author: David Woodhouse <dwmw@xxxxxxxxxxxx> AuthorDate: Thu, 05 Dec 2024 15:05:10 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Fri, 06 Dec 2024 10:41:59 +01:00 x86/kexec: Only swap pages for ::preserve_context mode There's no need to swap pages (which involves three memcopies for each page) in the plain kexec case. Just do a single copy from source to destination page. Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Baoquan He <bhe@xxxxxxxxxx> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx> Cc: Dave Young <dyoung@xxxxxxxxxx> Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx> Cc: Ard Biesheuvel <ardb@xxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Link: https://lore.kernel.org/r/20241205153343.3275139-5-dwmw2@xxxxxxxxxxxxx --- arch/x86/kernel/relocate_kernel_64.S | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S index fea650f..ca7f1e1 100644 --- a/arch/x86/kernel/relocate_kernel_64.S +++ b/arch/x86/kernel/relocate_kernel_64.S @@ -310,6 +310,9 @@ SYM_CODE_START_LOCAL_NOALIGN(swap_pages) movq %rdi, %rdx /* Save destination page to %rdx */ movq %rsi, %rax /* Save source page to %rax */ + testq %r11, %r11 /* Only actually swap for ::preserve_context */ + jz .Lnoswap + /* copy source page to swap page */ movq %r10, %rdi movl $512, %ecx @@ -324,6 +327,7 @@ SYM_CODE_START_LOCAL_NOALIGN(swap_pages) /* copy swap page to destination page */ movq %rdx, %rdi movq %r10, %rsi +.Lnoswap: movl $512, %ecx rep ; movsq
|