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From: Hans de Goede <hdegoede@redhat.com>
To: "Kuppuswamy,
	Sathyanarayanan"  <sathyanarayanan.kuppuswamy@linux.intel.com>,
	Xiaoyao Li <xiaoyao.li@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@kernel.org>,
	Mark Gross <mgross@linux.intel.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>
Cc: Peter H Anvin <hpa@zytor.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	Kirill Shutemov <kirill.shutemov@linux.intel.com>,
	Sean Christopherson <seanjc@google.com>,
	Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	platform-driver-x86@vger.kernel.org, bpf@vger.kernel.org,
	netdev@vger.kernel.org
Subject: Re: [PATCH v2 1/6] x86/tdx: Add TDREPORT TDX Module call support
Date: Thu, 8 Jul 2021 16:20:28 +0200	[thread overview]
Message-ID: <20c227e0-1299-0bf8-690c-f0260d39f420@redhat.com> (raw)
In-Reply-To: <46944ac2-4841-7f1d-4f54-ecb477f43d63@linux.intel.com>

Hi,

On 7/8/21 4:07 PM, Kuppuswamy, Sathyanarayanan wrote:
> 
> 
> On 7/8/21 1:16 AM, Xiaoyao Li wrote:
>>
>> Sorry I guess I didn't state it clearly during internal review.
>>
>> I suggest something like this
>>
>> if (ret != TDCALL_SUCCESS) {
>>      if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND)
>>          return -EINVAL;
>>      else if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY)
>>          return -EBUSY;
>>      else
>>          return -EFAULT; //I'm not sure if -EFAULT is proper.
>> }
> 
> As per current spec, TDCALL_INVALID_OPERAND, TDCALL_OPERAND_BUSY and
> 0 are the only possible return values. So I have checked for failure case
> in if condition and returned success by default. Any reason for specifically
> checking for success code ?

Yes, new error codes might be introduced and you might forget to
update this (or other) checks.

Checking for errors really MUST always be done by checking for
ret != success (typically ret != 0 or ret < 0).

Only checking for known error codes means that if somehow an
unknown error code gets thrown this gets treated as success,
which is not acceptable behavior.

Regards,

Hans



  reply	other threads:[~2021-07-08 14:20 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-07 20:42 [PATCH v2 0/6] Add TDX Guest Support (Attestation support) Kuppuswamy Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 1/6] x86/tdx: Add TDREPORT TDX Module call support Kuppuswamy Sathyanarayanan
2021-07-08  8:16   ` Xiaoyao Li
2021-07-08 14:07     ` Kuppuswamy, Sathyanarayanan
2021-07-08 14:20       ` Hans de Goede [this message]
2021-07-08 17:06         ` Kuppuswamy, Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 2/6] x86/tdx: Add GetQuote TDX hypercall support Kuppuswamy Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 3/6] x86/tdx: Add SetupEventNotifyInterrupt " Kuppuswamy Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 4/6] x86/tdx: Add TDX Guest event notify interrupt vector support Kuppuswamy Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 5/6] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver Kuppuswamy Sathyanarayanan
2021-07-08 22:21   ` Andy Lutomirski
2021-07-08 22:35     ` Dave Hansen
2021-07-09  0:38       ` Andi Kleen
2021-07-13  0:33         ` Kuppuswamy, Sathyanarayanan
2021-07-13  0:44           ` Dave Hansen
2021-07-08 23:34     ` Kuppuswamy, Sathyanarayanan
2021-07-08 23:36   ` Dan Williams
2021-07-08 23:57     ` Kuppuswamy, Sathyanarayanan
2021-07-09  0:20       ` Dan Williams
2021-07-09  0:36         ` Andi Kleen
2021-07-09  1:37           ` Dan Williams
2021-07-09  1:44             ` Andi Kleen
2021-07-09  2:04               ` Dan Williams
2021-07-09  2:43                 ` Kuppuswamy, Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 6/6] tools/tdx: Add a sample attestation user app Kuppuswamy Sathyanarayanan
2021-07-15  8:36   ` Mian Yousaf Kaukab
2021-07-15 15:19     ` Kuppuswamy, Sathyanarayanan

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