Re: [PATCH v5 1/3] x86/tdx: Add TDX Guest attestation interface driver

From: Kai Huang <kai.huang@intel.com>
To: Sathyanarayanan Kuppuswamy 
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	Wander Costa <wander@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Tony Luck <tony.luck@intel.com>, Andi Kleen <ak@linux.intel.com>,
	Isaku Yamahata <isaku.yamahata@gmail.com>,
	marcelo.cerri@canonical.com, tim.gardner@canonical.com,
	khalid.elmously@canonical.com, philip.cox@canonical.com,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 1/3] x86/tdx: Add TDX Guest attestation interface driver
Date: Wed, 04 May 2022 10:08:11 +1200	[thread overview]
Message-ID: <42e1af54bef03361c1a23dac8d1e4ffd8e66114a.camel@intel.com> (raw)
In-Reply-To: <cd48825b-7197-fc04-51e6-04bd8502d286@linux.intel.com>

On Tue, 2022-05-03 at 08:09 -0700, Sathyanarayanan Kuppuswamy wrote:
> 
> On 5/3/22 7:38 AM, Wander Costa wrote:
> > > I don't want to pollute the dmesg logs if possible. For IOCTL use case,
> > > the return value can be used to understand the failure reason from user
> > > code. But for initcall failure, pr_err message is required to understand
> > > the failure reason.
> > How often is this call expected to fail?
> 
> In general, it should not fail (so very low fail frequency). But the
> point is, we can easily understand this failure from user end. So we
> don't need to print more in non-debug environment.
> 
> > 

To support your statement, all the error codes return to userspace need to be
clearly documented around the IOCTL in the uapi header.  But I think you have to
do this anyway.

-- 
Thanks,
-Kai