On 01/17/18 at 06:14pm, Linus Torvalds wrote: > On Wed, Jan 17, 2018 at 5:47 PM, Dave Young <dyoung@xxxxxxxxxx> wrote: > > > > It does not work with just once wbinvd(), and it only works with > > removing the wbinvd() for me. Tom's new post works for me as well > > since my cpu is an Intel i5-4200U. > > Intriguing. > > It's not like the wbinvd really should be that much of a deal. > > I think Tom's patch is fine and should be applied, but it does worry > me a bit that even a single wbinvd makes that much of a difference for > you. There is very little logical reason I can think of that a wbinvd > should make any difference what-so-ever on an i5-4200U. > > I wonder if you have some system issues, and wbinvd just happens to > trigger them. But I think we do wbinvd before a suspend-to-RAM too > (it's "ACPI_FLUSH_CPU_CACHE()" in the ACPI code). And the dmr code > dioes "wbinvd_on_all_cpus()" which does a cross-call etc. > > Would you mind experimenting a bit with that wbinvd? > > In particular, what happens if you enable it (so it's not hidden by > the SME check), but you move it up to before interrupts are disabled? Will play with it more. Actually I found the hang seems happens in code of arch/x86/kernel/relocate_kernel_64.S, there is another wbinvd there as well. > > I'm wondering if there is some issue with MCE generation and wbinvd > and whatever, and doing it when the CPU is down and interrupts are > disabled causes some system issue.. > > Does anybody have any other ideas? > > Linus _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
