linux-kernel - Re: [PATCH v7 06/20] x86/virt/tdx: Shut down TDX module in case of error

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Message-ID: <Y3ySxEr64HkUaEDq@hirez.programming.kicks-ass.net>
Date:   Tue, 22 Nov 2022 10:13:40 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Kai Huang <kai.huang@...el.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-mm@...ck.org, seanjc@...gle.com, pbonzini@...hat.com,
        dave.hansen@...el.com, dan.j.williams@...el.com,
        rafael.j.wysocki@...el.com, kirill.shutemov@...ux.intel.com,
        ying.huang@...el.com, reinette.chatre@...el.com,
        len.brown@...el.com, tony.luck@...el.com, ak@...ux.intel.com,
        isaku.yamahata@...el.com, chao.gao@...el.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, bagasdotme@...il.com,
        sagis@...gle.com, imammedo@...hat.com
Subject: Re: [PATCH v7 06/20] x86/virt/tdx: Shut down TDX module in case of
 error

On Mon, Nov 21, 2022 at 01:26:28PM +1300, Kai Huang wrote:

> +/*
> + * Call the SEAMCALL on all online CPUs concurrently.  Caller to check
> + * @sc->err to determine whether any SEAMCALL failed on any cpu.
> + */
> +static void seamcall_on_each_cpu(struct seamcall_ctx *sc)
> +{
> +	on_each_cpu(seamcall_smp_call_function, sc, true);
> +}

Suppose the user has NOHZ_FULL configured, and is already running
userspace that will terminate on interrupt (this is desired feature for
NOHZ_FULL), guess how happy they'll be if someone, on another parition,
manages to tickle this TDX gunk?