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Re: [patch] x86/realmode: Make stack lock work in trampoline_compat()
- To: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
- From: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
- Date: Tue, 30 May 2023 14:12:48 +0300
- Cc: LKML <linux-kernel@xxxxxxxxxxxxxxx>, x86@xxxxxxxxxx, David Woodhouse <dwmw2@xxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Brian Gerst <brgerst@xxxxxxxxx>, 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>, 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>, "Michael Kelley (LINUX)" <mikelley@xxxxxxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
- Delivery-date: Tue, 30 May 2023 11:13:10 +0000
- Feedback-id: ie3994620:Fastmail
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On Tue, May 30, 2023 at 12:46:22PM +0200, Thomas Gleixner wrote:
> The stack locking and stack assignment macro LOAD_REALMODE_ESP fails to
> work when invoked from the 64bit trampoline entry point:
>
> trampoline_start64
> trampoline_compat
> LOAD_REALMODE_ESP <- lock
>
> Accessing tr_lock is only possible from 16bit mode. For the compat entry
> point this needs to be pa_tr_lock so that the required relocation entry is
> generated. Otherwise it locks the non-relocated address which is
> aside of being wrong never cleared in secondary_startup_64() causing all
> but the first CPU to get stuck on the lock.
>
> Make the macro take an argument lock_pa which defaults to 0 and rename it
> to LOCK_AND_LOAD_REALMODE_ESP to make it clear what this is about.
>
> Fixes: f6f1ae9128d2 ("x86/smpboot: Implement a bit spinlock to protect the
> realmode stack")
> Reported-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
--
Kiryl Shutsemau / Kirill A. Shutemov
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