Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Feedback-ID: ie3994620:Fastmail
Date:   Tue, 30 May 2023 14:12:48 +0300
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     LKML <linux-kernel@vger.kernel.org>, x86@kernel.org,
        David Woodhouse <dwmw2@infradead.org>,
        Andrew Cooper <andrew.cooper3@citrix.com>,
        Brian Gerst <brgerst@gmail.com>,
        Arjan van de Veen <arjan@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Paul McKenney <paulmck@kernel.org>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Sean Christopherson <seanjc@google.com>,
        Oleksandr Natalenko <oleksandr@natalenko.name>,
        Paul Menzel <pmenzel@molgen.mpg.de>,
        "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
        Piotr Gorski <lucjan.lucjanov@gmail.com>,
        Usama Arif <usama.arif@bytedance.com>,
        Juergen Gross <jgross@suse.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        xen-devel@lists.xenproject.org,
        Russell King <linux@armlinux.org.uk>,
        Arnd Bergmann <arnd@arndb.de>,
        linux-arm-kernel@lists.infradead.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
        linux-csky@vger.kernel.org,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        linux-mips@vger.kernel.org,
        "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
        Helge Deller <deller@gmx.de>, linux-parisc@vger.kernel.org,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        linux-riscv@lists.infradead.org,
        Mark Rutland <mark.rutland@arm.com>,
        Sabin Rapan <sabrapan@amazon.com>,
        "Michael Kelley (LINUX)" <mikelley@microsoft.com>,
        Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [patch] x86/realmode: Make stack lock work in trampoline_compat()
Message-ID: <20230530111248.lzt77sydi7x3wau7@box.shutemov.name>
References: <20230508181633.089804905@linutronix.de>
 <20230508185218.962208640@linutronix.de>
 <20230524204818.3tjlwah2euncxzmh@box.shutemov.name>
 <87y1lbl7r6.ffs@tglx>
 <87sfbhlwp9.ffs@tglx>
 <20230529023939.mc2akptpxcg3eh2f@box.shutemov.name>
 <87bki3kkfi.ffs@tglx>
 <20230529203129.sthnhzgds7ynddxd@box.shutemov.name>
 <87h6rujdvl.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <87h6rujdvl.ffs@tglx>
Precedence: bulk

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@linux.intel.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

-- 
  Kiryl Shutsemau / Kirill A. Shutemov