From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 41B47244699; Mon, 19 May 2025 17:21:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747675317; cv=none; b=GyOw9p/Xdtc3TncwrS/5NLPNtTjTdZlMWQE3w1kE+mPzB6foOA4/Ly6a11C8k9ELa2dNn5pJSgA+Zk0BbXaBR3Ma1NCF5/UK8cqH2mxQqZJAAy4LQlm/qmbq8VYeT3zMnZuTGZRX2gJOjSr6xm/rj8xtyuMrelOOaJdR6qixJ54= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747675317; c=relaxed/simple; bh=3Kfs+8UoIc+Nl4DLIGOmtcSxf3HMGxNNUKXjDdKqLak=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=KJrxIWYosLmfGfs+Udf1TVeVKQXO+Cdghyu2b3pQ8uQXKp7U9B8WwmKk6/1OdyOdKTSghz8uH7k2DdCnWwDRXGZWwaiDENBED1M0csbztVkYtbpWpXxigKYerXt/VwDvNvzHQzXOwPZ+Y3dEe3gr8nXI6JKLy02jIUS/oDN0SEA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sLoJZ6oe; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sLoJZ6oe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 945B2C4CEE9; Mon, 19 May 2025 17:21:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747675317; bh=3Kfs+8UoIc+Nl4DLIGOmtcSxf3HMGxNNUKXjDdKqLak=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sLoJZ6oeZHx9FTtWRVsQPjvf/L4cRmjeJ2pmqJfuE47U5peYGpc67FKYy8Yu76veQ mdBMVlXHnTsrOIzYROdBeeuD2+uUyE4MRLmGDB2MkxkCNjtsHcfJqo3p/liMx0iJuC QcKGrCU2JnXQwIQ21WUykSI9LWFjIJ10SlpsPLTI26bdygGh15Lh0TlHSY7MFWFsNi /FEgRXfpN8W7BXUrzyquHdomQJiwT/uXWn98gtjgwdSN4MupPJZuS2D4pViZpeUKk+ GhbEcvYZHvdS3HE+5DTRLtUJkHqgyojGcZykjV0qJVpACwMoOXPhnh3Hfm+WSUHOZf Ug6hblIsscA2g== Date: Mon, 19 May 2025 20:21:51 +0300 From: Jarkko Sakkinen To: Elena Reshetova Cc: dave.hansen@intel.com, seanjc@google.com, kai.huang@intel.com, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, asit.k.mallick@intel.com, vincent.r.scarlata@intel.com, chongc@google.com, erdemaktas@google.com, vannapurve@google.com, dionnaglaze@google.com, bondarn@google.com, scott.raynor@intel.com Subject: Re: [PATCH v5 1/5] x86/sgx: Introduce a counter to count the sgx_(vepc_)open() Message-ID: References: <20250519072603.328429-1-elena.reshetova@intel.com> <20250519072603.328429-2-elena.reshetova@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250519072603.328429-2-elena.reshetova@intel.com> On Mon, May 19, 2025 at 10:24:27AM +0300, Elena Reshetova wrote: > Currently SGX does not have a global counter to count the > active users from userspace or hypervisor. Implement such a counter, > sgx_usage_count. It will be used by the driver when attempting > to call EUPDATESVN SGX instruction. > > Suggested-by: Sean Christopherson > Signed-off-by: Elena Reshetova > --- > arch/x86/kernel/cpu/sgx/driver.c | 1 + > arch/x86/kernel/cpu/sgx/encl.c | 1 + > arch/x86/kernel/cpu/sgx/main.c | 14 ++++++++++++++ > arch/x86/kernel/cpu/sgx/sgx.h | 3 +++ > arch/x86/kernel/cpu/sgx/virt.c | 2 ++ > 5 files changed, 21 insertions(+) > > diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c > index 7f8d1e11dbee..b5ffe104af4c 100644 > --- a/arch/x86/kernel/cpu/sgx/driver.c > +++ b/arch/x86/kernel/cpu/sgx/driver.c > @@ -19,6 +19,7 @@ static int sgx_open(struct inode *inode, struct file *file) > struct sgx_encl *encl; > int ret; > > + sgx_inc_usage_count(); > encl = kzalloc(sizeof(*encl), GFP_KERNEL); > if (!encl) > return -ENOMEM; > diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c > index 279148e72459..3b54889ae4a4 100644 > --- a/arch/x86/kernel/cpu/sgx/encl.c > +++ b/arch/x86/kernel/cpu/sgx/encl.c > @@ -765,6 +765,7 @@ void sgx_encl_release(struct kref *ref) > WARN_ON_ONCE(encl->secs.epc_page); > > kfree(encl); > + sgx_dec_usage_count(); > } > > /* > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > index 8ce352fc72ac..80d565e6f2ad 100644 > --- a/arch/x86/kernel/cpu/sgx/main.c > +++ b/arch/x86/kernel/cpu/sgx/main.c > @@ -914,6 +914,20 @@ int sgx_set_attribute(unsigned long *allowed_attributes, > } > EXPORT_SYMBOL_GPL(sgx_set_attribute); > > +/* Counter to count the active SGX users */ > +static atomic64_t sgx_usage_count; > + > +int sgx_inc_usage_count(void) > +{ > + atomic64_inc(&sgx_usage_count); > + return 0; > +} > + > +void sgx_dec_usage_count(void) > +{ > + atomic64_dec(&sgx_usage_count); > +} > + > static int __init sgx_init(void) > { > int ret; > diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h > index d2dad21259a8..f5940393d9bd 100644 > --- a/arch/x86/kernel/cpu/sgx/sgx.h > +++ b/arch/x86/kernel/cpu/sgx/sgx.h > @@ -102,6 +102,9 @@ static inline int __init sgx_vepc_init(void) > } > #endif > > +int sgx_inc_usage_count(void); > +void sgx_dec_usage_count(void); > + > void sgx_update_lepubkeyhash(u64 *lepubkeyhash); > > #endif /* _X86_SGX_H */ > diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c > index 7aaa3652e31d..83de0907f32c 100644 > --- a/arch/x86/kernel/cpu/sgx/virt.c > +++ b/arch/x86/kernel/cpu/sgx/virt.c > @@ -255,6 +255,7 @@ static int sgx_vepc_release(struct inode *inode, struct file *file) > xa_destroy(&vepc->page_array); > kfree(vepc); > > + sgx_dec_usage_count(); > return 0; > } > > @@ -262,6 +263,7 @@ static int sgx_vepc_open(struct inode *inode, struct file *file) > { > struct sgx_vepc *vepc; > > + sgx_inc_usage_count(); > vepc = kzalloc(sizeof(struct sgx_vepc), GFP_KERNEL); > if (!vepc) > return -ENOMEM; > -- > 2.45.2 > Maybe just use raw atomic_inc() and atomic_dec() at the sites? IMHO, it makes only sense to wrap, when it makes sense to wrap. BR, Jarkko