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 623F51552E3; Fri, 4 Apr 2025 07:48:13 +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=1743752893; cv=none; b=c019kRx8GQ3Wfiip1ijgIAA66UYLE6eQnqgdOfmgjbD4Q2x2KJ4t3q1XAW+gfGvoPaK3YnaQzs7bC2vFzUeabNesK2imog0JbiiRBmAuirHJ3C0foly1ZFgy3y6sPmZJAvzJkElz+RADXs70H2+Cgi+dWt+iY2oSijrOsMNCyng= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743752893; c=relaxed/simple; bh=CWgn0iuDB61o8APfrFwOk0rOr7NMFOnhrduS8Ub4R/4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GXHQtT4v7IEkX1ukmvpHIJTTtYSHh8UjSO0ijgZABUSyZ6En8up/Eo39Jf26JR2C7Svl/3plF1MXDs3764cn9RAH3ZfwBm4zxt0LU8kh3M8tgivYXcb7oaW8hZJic+f6IEZIQ+lc5uhPhw4I3jhrylsNNoUgC9pSiMlrRHBuKLY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EdzSo6AR; 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="EdzSo6AR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 57793C4CEDD; Fri, 4 Apr 2025 07:48:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1743752892; bh=CWgn0iuDB61o8APfrFwOk0rOr7NMFOnhrduS8Ub4R/4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EdzSo6ARK1UfzhsxiPzjjCufTuaMzJ/BY7wMw7xL80+y7Pv7zoZpg9rTeI61T8hJD L6spvadDV+Z86S2YeB/zmbgelCx/RxW7P0D3izF3MS7vvSYWMr44sf71moHQWXWR+E D8OffDtA26EpHHJNm6lKMvE8OkD6wLw8UW+CPy8mlsZNpzmP4TYJeyp17fyYxhe5IY tm+C+tT2GJGhvEn/lW1Qg6W3DvO/U70VtCbwYUskDPeT//F7syTFUgzAEqVGcIsIGA h+6BO29HF3v6TsthlBgJOVZZpZS6YoA/I36syp2pZwxKbGE7woxmphMAfDN0G2HDPU 1KmoAz22MGZbQ== Date: Fri, 4 Apr 2025 10:48:08 +0300 From: Jarkko Sakkinen To: "Reshetova, Elena" Cc: "Annapurve, Vishal" , "Hansen, Dave" , "linux-sgx@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "x86@kernel.org" , "Mallick, Asit K" , "Scarlata, Vincent R" , "Cai, Chong" , "Aktas, Erdem" , "dionnaglaze@google.com" , "bondarn@google.com" , "Raynor, Scott" Subject: Re: [PATCH v2 2/2] x86/sgx: Implement EUPDATESVN and opportunistically call it during first EPC page alloc Message-ID: References: <20250328125859.73803-3-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: On Fri, Apr 04, 2025 at 06:53:17AM +0000, Reshetova, Elena wrote: > > On Wed, Apr 02, 2025 at 01:11:25PM +0000, Reshetova, Elena wrote: > > > > > current SGX kernel code does not handle such errors in any other way > > > > > than notifying that operation failed for other ENCLS leaves. So, I don't > > > > > see why ENCLS[EUPDATESVN] should be different from existing > > behaviour? > > > > > > > > While not disagreeing fully (it depends on call site), in some > > > > situations it is more difficult to take more preventive actions. > > > > > > > > This is a situation where we know that there are *zero* EPC pages in > > > > traffic so it is relatively easy to stop the madness, isn't it? > > > > > > > > I guess the best action would be make sgx_alloc_epc_page() return > > > > consistently -ENOMEM, if the unexpected happens. > > > > > > But this would be very misleading imo. We do have memory, even page > > > allocation might function as normal in EPC, the only thing that is broken > > > can be EUPDATESVN functionality. Returning -ENOMEM in this case seems > > > wrong. > > > > This makes it not misleading at all: > > > > pr_err("EUPDATESVN: unknown error %d\n", ret); > > > > Since hardware should never return this, it indicates a kernel bug. > > OK, so you propose in this case to print the above message, sgx_updatesvn > returning an error, and then NULL from __sgx_alloc_epc_page_from_node and > the __sgx_alloc_epc_page returning -ENOMEM after an iteration over > a whole set of numa nodes given that we will keep getting the unknown error > on each node upon trying to do an allocation from each one? I'd disable ioctl's in this case and return -ENOMEM. It's a cheap sanity check. Should not ever happen, but if e.g., a new kernel patch breaks anything, it could help catching issues. We are talking here about situation that is never expected to happen so I don't think it is too heavy hammer here. Here it makes sense because not much effort is required to implement the counter-measures. > > Best Regards, > Elena. > > > BR, Jarkko