linux-kernel - Re: [PATCH v13 5/5] x86/sgx: Enable automatic SVN updates for SGX enclaves

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Message-ID: <c4fd656e3abc77a9bc0c04aef3e6354fdc40b8bd.camel@intel.com>
Date: Wed, 13 Aug 2025 11:07:55 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "Reshetova, Elena" <elena.reshetova@...el.com>, "Hansen, Dave"
	<dave.hansen@...el.com>
CC: "seanjc@...gle.com" <seanjc@...gle.com>, "mingo@...nel.org"
	<mingo@...nel.org>, "Scarlata, Vincent R" <vincent.r.scarlata@...el.com>,
	"x86@...nel.org" <x86@...nel.org>, "jarkko@...nel.org" <jarkko@...nel.org>,
	"Annapurve, Vishal" <vannapurve@...gle.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Mallick, Asit K" <asit.k.mallick@...el.com>,
	"Aktas, Erdem" <erdemaktas@...gle.com>, "Cai, Chong" <chongc@...gle.com>,
	"Bondarevska, Nataliia" <bondarn@...gle.com>, "linux-sgx@...r.kernel.org"
	<linux-sgx@...r.kernel.org>, "Raynor, Scott" <scott.raynor@...el.com>
Subject: Re: [PATCH v13 5/5] x86/sgx: Enable automatic SVN updates for SGX
 enclaves

> 
> Note: while in such cases the underlying crypto assets are regenrated, it
							     ^
							     regenerated


[...]

> +/* Mutex to ensure no concurrent EPC accesses during EUPDATESVN */
> +static DEFINE_MUTEX(sgx_svn_lock);
> +
>  int sgx_inc_usage_count(void)
>  {
> +	int ret;
> +
> +	guard(mutex)(&sgx_svn_lock);
> +
> +	if (sgx_usage_count++ == 0) {
> +		ret = sgx_update_svn();
> +		if (ret)
> +			sgx_usage_count--;
> +		return ret;
> +	}
> +

To me, I would prefer:

int sgx_inc_usage_count(void)
{
	guard(mutex)(&sgx_svn_lock);

	if (!sgx_usage_count) {
		int ret = sgx_update_svn();
		if (ret)
			return ret;
	}

	sgx_usage_count++;

	return 0;
}