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Re: [patch 35/37] x86/smpboot: Support parallel startup of secondary CPUs
- To: Brian Gerst <brgerst@xxxxxxxxx>
- From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
- Date: Sat, 15 Apr 2023 23:06:38 +0200
- Cc: LKML <linux-kernel@xxxxxxxxxxxxxxx>, x86@xxxxxxxxxx, David Woodhouse <dwmw@xxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Arjan van de Veen <arjan@xxxxxxxxxxxxxxx>, Paolo Bonzini <pbonzini@xxxxxxxxxx>, Paul McKenney <paulmck@xxxxxxxxxx>, Tom Lendacky <thomas.lendacky@xxxxxxx>, Sean Christopherson <seanjc@xxxxxxxxxx>, Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx>, Paul Menzel <pmenzel@xxxxxxxxxxxxx>, "Guilherme G. Piccoli" <gpiccoli@xxxxxxxxxx>, Piotr Gorski <lucjan.lucjanov@xxxxxxxxx>, David Woodhouse <dwmw@xxxxxxxxxxxx>, Usama Arif <usama.arif@xxxxxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, Russell King <linux@xxxxxxxxxxxxxxx>, Arnd Bergmann <arnd@xxxxxxxx>, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, Catalin Marinas <catalin.marinas@xxxxxxx>, Will Deacon <will@xxxxxxxxxx>, Guo Ren <guoren@xxxxxxxxxx>, linux-csky@xxxxxxxxxxxxxxx, Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>, linux-mips@xxxxxxxxxxxxxxx, "James E.J. Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>, Helge Deller <deller@xxxxxx>, linux-parisc@xxxxxxxxxxxxxxx, Paul Walmsley <paul.walmsley@xxxxxxxxxx>, Palmer Dabbelt <palmer@xxxxxxxxxxx>, linux-riscv@xxxxxxxxxxxxxxxxxxx, Mark Rutland <mark.rutland@xxxxxxx>, Sabin Rapan <sabrapan@xxxxxxxxxx>
- Delivery-date: Sat, 15 Apr 2023 21:06:46 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On Sat, Apr 15 2023 at 09:22, Brian Gerst wrote:
> On Fri, Apr 14, 2023 at 7:45 PM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>> @@ -248,10 +311,20 @@ SYM_INNER_LABEL(secondary_startup_64_no_
>> *
>> * RDX contains the per-cpu offset
>> */
>> - movq pcpu_hot + X86_current_task(%rdx), %rax
>> - movq TASK_threadsp(%rax), %rsp
>> + movq pcpu_hot + X86_top_of_stack(%rdx), %rsp
>
> Switching to using pcpu_hot.top_of_stack is ok, but it's not
> completely equivalent. top_of_stack points to the end of the pt_regs
> structure, while the kernel stack starts below pt_regs even for kernel
> threads. So you need to subtract PTREGS_SIZE from the stack pointer
> after this.
>
> This change should also be a separate patch.
You're right on both counts.
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