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

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Message-ID: <Y3yR/NQwLYfIqode@hirez.programming.kicks-ass.net>
Date:   Tue, 22 Nov 2022 10:10:20 +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:

> +/*
> + * Data structure to make SEAMCALL on multiple CPUs concurrently.
> + * @err is set to -EFAULT when SEAMCALL fails on any cpu.
> + */
> +struct seamcall_ctx {
> +	u64 fn;
> +	u64 rcx;
> +	u64 rdx;
> +	u64 r8;
> +	u64 r9;
> +	atomic_t err;
> +};

> @@ -166,6 +180,25 @@ static int __always_unused seamcall(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
>  	}
>  }
>  
> +static void seamcall_smp_call_function(void *data)
> +{
> +	struct seamcall_ctx *sc = data;
> +	int ret;
> +
> +	ret = seamcall(sc->fn, sc->rcx, sc->rdx, sc->r8, sc->r9, NULL, NULL);
> +	if (ret)
> +		atomic_set(&sc->err, -EFAULT);
> +}

Can someone explain me this usage of atomic_t, please?