From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3DE33C35657 for ; Fri, 21 Feb 2020 16:38:19 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id B01D524650 for ; Fri, 21 Feb 2020 16:38:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="Jac+jXV/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B01D524650 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 3F5784AECE; Fri, 21 Feb 2020 11:38:18 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@kernel.org Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id piEqkdUX0Cfy; Fri, 21 Feb 2020 11:38:17 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 427E04AED2; Fri, 21 Feb 2020 11:38:17 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id C72294AECE for ; Fri, 21 Feb 2020 11:38:15 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id le5QQPVwvk5r for ; Fri, 21 Feb 2020 11:38:14 -0500 (EST) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id B810C4AEBF for ; Fri, 21 Feb 2020 11:38:14 -0500 (EST) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8122D24650; Fri, 21 Feb 2020 16:38:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582303093; bh=vx7DYqshiSvtTa72/koYpApCGou0XWnWIMWdMy/RIAc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Jac+jXV/ZV53KVQTPBYVTDEppW4Mq4MV7IEX4C2znk1vl5Xji4vgwggxYqp8VBniq MszcHuSTDRzYJ5QykS2QZRKduROKCZ4yS0L5dl6E7HBeXLGDWSZuz0BSlkF1swZOXs roIpTwV/NgIxjC58XDtWI6M5pza1jIkDUPLArW6o= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1j5BJb-007593-PI; Fri, 21 Feb 2020 16:38:11 +0000 MIME-Version: 1.0 Date: Fri, 21 Feb 2020 16:38:11 +0000 From: Marc Zyngier To: James Morse Subject: Re: [PATCH 0/3] KVM: arm64: Ask the compiler to __always_inline functions used by KVM at HYP In-Reply-To: <228ef9d9-1ded-05ee-22e5-0158a0e47d82@arm.com> References: <20200220165839.256881-1-james.morse@arm.com> <228ef9d9-1ded-05ee-22e5-0158a0e47d82@arm.com> Message-ID: <6479dd67fbe12c6517551dbd79dc7461@kernel.org> X-Sender: maz@kernel.org User-Agent: Roundcube Webmail/1.3.10 X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: james.morse@arm.com, ard.biesheuvel@linaro.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, catalin.marinas@arm.com, will@kernel.org, samitolvanen@google.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: Catalin Marinas , Ard Biesheuvel , linux-arm-kernel@lists.infradead.org, Sami Tolvanen , Will Deacon , kvmarm@lists.cs.columbia.edu X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi James, On 2020-02-21 14:57, James Morse wrote: > Hi Marc, > > On 21/02/2020 12:55, Marc Zyngier wrote: >> On 2020-02-20 16:58, James Morse wrote: >>> It turns out KVM relies on the inline hint being honoured by the >>> compiler >>> in quite a few more places than expected. Something about the Shadow >>> Call >>> Stack support[0] causes the compiler to avoid inline-ing and to place >>> these functions outside the __hyp_text. This ruins KVM's day. >>> >>> Add the simon-says __always_inline annotation to all the static >>> inlines that KVM calls from HYP code. >>> >>> This series based on v5.6-rc2. >> >> Many thanks for going through all this. >> >> I'm happy to take it if Catalin or Will ack the arm64 patches. >> It case we decide to go the other way around: >> >> Acked-by: Marc Zyngier >> >> One thing I'd like to look into though is a compile-time check that >> nothing in the hyp_text section has a reference to a non-hyp_text >> symbol. > > Heh, that hypothetical tool would choke on things like > arch/arm64/kvm/hyp/tlb.c: > | static void __hyp_text __tlb_switch_to_guest_vhe(...) > | { > > [...] > > | local_irq_save(cxt->flags); > > which calls trace_hardirqs_off() ... which is absolutely fine because > this only happens on VHE. Duh, indeed. > To do it purely with the section information, you'd need to separate > all the VHE code... (maybe as a debug option that only runs when VHE > is turned off?) We may have to to that anyway at some point. If the "KVM compartment" thing becomes real, we may have to end-up compiling both separately (and jettison the one we don't need at runtime). >> We already have checks around non-init symbols pointing to init >> symbols, >> and I was wondering if we could reuse this for fun and profit... > > I think objtool is the tool-of-the-future that can do this. You need > something that believes everything behind has_vhe() is unreachable... I need to educate myself about objtool. Seems to be the miracle cure for a lot of ailments! ;-) Anyway, I've now queued the series for 5.6. M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm