From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (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 1AF1313C9A7 for ; Wed, 17 Apr 2024 15:06:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713366420; cv=none; b=oxHo68LlxrVGqESjuAyOV4dH+X/VyhWq9hno3vHKjXbegR3CsGvFmEBWWLYHA1VV+sf90FQLuC+d779iqVSHSqJx/mtFccc/BnyKUUbk5RQH4AykcDxGAMRLIqNkSS72/ECiKJGCQioZTIVh1q49kuqh8VUMpkEe58eBEkcosik= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713366420; c=relaxed/simple; bh=UNPb0zlkcnhUQib87xagHEcOVpvTSkc5NdfcbnpIiM8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ixL9Ac1/2cG4Lc9MqWrErJBX7FAb1OsP970BZK09/YkWzJnyxEYmhOTWfmarhRCnZCXBRm9JKDs1pJIGQzNZgxQ+RvupnmwSN3fkJdZ6gN4SDOcVxhTKCGx+7VWYwysOEDruXf6aGZd/+haMAcNcR2/nsh2BzIxOnw6BmaCSEh4= ARC-Authentication-Results:i=1; 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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=PK+OC6ZQAW/LLmhCpbeswphwxvOIazSVbLSYpIa3mTvPRZYSEnfeVHcBDbECe1DJ6 1T3kzfZ8pUbdSB001ATu/aZcNIJOMY/u8gto339ZvnUFsPLDXAYIbRiAXi0Jcxxbkl Wg/J1frV+S7JOIZBx8hSRwgXqHIi2sYK1ERN+aBDGm4xPvL/Ro5aBeo94K5FxlHvFu +gbZLOW3GD/Og+fowms1ymtOq92S/4VHRXIc55SFM6EOl8ZFUv23C6t8LQhJIS+FxP HI7E7ZaMOXrtULvO1M/h2oYnIrDyjDUj+Tt+E3aEb8p+UjnS19yVWBFgaahziBgrFJ 2w+Znk7vlDoGw== Message-ID: Date: Wed, 17 Apr 2024 08:06:31 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/1] x86/fred: Fix INT80 emulation for FRED To: Borislav Petkov Cc: linux-kernel@vger.kernel.org, luto@kernel.org, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com References: <20240417063001.3773507-1-xin@zytor.com> <20240417093813.GBZh-YhSQCXgy3OxFI@fat_crate.local> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/17/2024 2:38 AM, Borislav Petkov wrote: > On Tue, Apr 16, 2024 at 11:30:01PM -0700, Xin Li (Intel) wrote: >> 3) The FRED kernel entry handler does *NOT* dispatch INT instructions, >> which is of event type EVENT_TYPE_SWINT, so compared with >> do_int80_emulation(), there is no need to do any user mode check. > > What does that mean? > > An event handler doesn't dispatch INT insns? > > /me is confused. > Maybe better to say? The FRED kernel entry handler fred_entry_from_kernel() calls fred_bad_type() if an event is of type EVENT_TYPE_SWINT because Kernel does not use INT insns! So if the kernel is handling an INT insn, it can only be from a user level application. >> + * A dedicated FRED INT80 handler duplicates quite a bit of the code in >> + * do_int80_emulation(), but it avoids sprinkling more tests and seems >> + * more readable. Just remember that we can always unify common stuff >> + * later if it turns out that it won't diverge anymore, i.e., after the >> + * FRED code settles. >> + */ > > And this is talking about duplication above and that text is duplicated > from the commit message. :) I wanted to keep it as a TODO. I can remove it in the next iteration. > > I'll zap it when applying. > > Thx. >