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=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=ham 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 1DC54C4727C for ; Thu, 1 Oct 2020 10:07:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C4BFC21707 for ; Thu, 1 Oct 2020 10:07:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="hWAwHmbv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731846AbgJAKH5 (ORCPT ); Thu, 1 Oct 2020 06:07:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726992AbgJAKH5 (ORCPT ); Thu, 1 Oct 2020 06:07:57 -0400 Received: from mail-wr1-x444.google.com (mail-wr1-x444.google.com [IPv6:2a00:1450:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C4E7C0613D0 for ; Thu, 1 Oct 2020 03:07:57 -0700 (PDT) Received: by mail-wr1-x444.google.com with SMTP id c18so4956152wrm.9 for ; Thu, 01 Oct 2020 03:07:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=NUXTaxsY7NaXachlgBjQGlyIz9BkJJJNfphdb55Lwns=; b=hWAwHmbvpL/fUYlWSvL43XM6O7kxQXolhLytRW4KP0Z6zlw+30mFb+/NKei2wkyFjW AFJtE+PMI/8r5JP1ykHUGVR4ysFO99EDr4a4/9WUldbEdf+iWIoIG2MyvVu/GGNvk/q9 CwVZ7wkgPJe+3LCECgMYFCtBvbG7Z3EYknif+gIIDLkj+/ir0S1ToxC9pmbjg1Bfgm14 i1ARfg5oRTR6difVdGKpxvzYyyEubV3G0o9JxizzDMIQuHMmG1K87BjB2Wtc9BlxKcIQ wyzQjihFjT1hNaUUEMeAKf4Etzh4HG37dmxP+26a9fblWLk5m9/ErrxU1igmKfxxYVD8 KMtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=NUXTaxsY7NaXachlgBjQGlyIz9BkJJJNfphdb55Lwns=; b=fMw51T4+jRXzHfoESN0UV6H46Jub+06/K0h++bzlhR0jBww7VTM9XukSjCw0zwmYPu 3tx/M+QpaymVWwG9dbBT0F8NLOoST1cQbjygsv7kKVCRlidKkDGSX6P7fW32KtL3qEcu vFA7SR/RCFJRw/OFxkedA2LJfriQI+PaUBY7hrI6WtUkOIgPe3gjGBoPciKTST5ZvItd RgvJN34WstwGG+jmLpug4znbuVYo2trlxQvflckwPVjxKu8XkdAs5jTUTgTbDnPt4/P7 hxADyNYpWUkHYxG9jxjbsrrasxG5lT4KOriLdCVm9JsJFm83Enm/D/I5o3PytkQw+dMV ESww== X-Gm-Message-State: AOAM531X94YsuzoCtvleNXjWuY7QR9pnfLzonCo424+uh7PzLukZGkgi YAryN/FLWkaZGc8jwxs4TZ+RRw== X-Google-Smtp-Source: ABdhPJw+OAQXeCZAgHYba/uf4iegthEQioEJaaLoGJ3ir7TtqURdZbSjpiI/+z+XYaADHTW1Un++OQ== X-Received: by 2002:adf:f750:: with SMTP id z16mr7697659wrp.377.1601546875447; Thu, 01 Oct 2020 03:07:55 -0700 (PDT) Received: from google.com ([2a00:79e0:d:109:4a0f:cfff:fe4a:6363]) by smtp.gmail.com with ESMTPSA id p14sm8281917wmc.8.2020.10.01.03.07.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Oct 2020 03:07:54 -0700 (PDT) Date: Thu, 1 Oct 2020 11:07:50 +0100 From: Andrew Scull To: George-Aurelian Popescu Cc: maz@kernel.org, catalin.marinas@arm.com, will@kernel.org, masahiroy@kernel.org, michal.lkml@markovi.net, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, natechancellor@gmail.com, ndesaulniers@google.com, dbrazdil@google.com, broonie@kernel.org, maskray@google.com, keescook@chromium.org, akpm@linux-foundation.org, dvyukov@google.com, elver@google.com, tglx@linutronix.de, arnd@arndb.de Subject: Re: [PATCH 03/14] KVM: arm64: Add support for creating and checking a logging buffer inside hyp/nVHE Message-ID: <20201001100750.GA541087@google.com> References: <20200914172750.852684-1-georgepope@google.com> <20200914172750.852684-4-georgepope@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200914172750.852684-4-georgepope@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 14, 2020 at 05:27:39PM +0000, George-Aurelian Popescu wrote: > From: George Popescu > > Share a buffer between the kernel and the hyp/nVHE code by using the > macros from kvm_debug_buffer.h. > > The buffer is composed of a writing index and a statically allocated > array. The writing index counts how many elements have been written inside > the buffer and should be set to zero whenever the code goes back to > EL2 with the clear_kvm_debug_buffer macro. > > To avoid consistency problems the buffer is defined per_cpu and is designed > to be read-only from the kernel perspective. > > Check if there is any logging data from hyp/nVHE code. > > Every time when the state returns back to the kernel after an hvc call, > the __kvm_arm_check_debug_buffer macro checks if there is any data inside > one of the predefined buffers. > > Signed-off-by: George Popescu > --- > arch/arm64/include/asm/kvm_debug_buffer.h | 34 +++++++++++++++++++++++ > arch/arm64/include/asm/kvm_host.h | 6 ++++ > arch/arm64/kvm/hyp/hyp-entry.S | 2 +- > 3 files changed, 41 insertions(+), 1 deletion(-) > create mode 100644 arch/arm64/include/asm/kvm_debug_buffer.h > > diff --git a/arch/arm64/include/asm/kvm_debug_buffer.h b/arch/arm64/include/asm/kvm_debug_buffer.h > new file mode 100644 > index 000000000000..30c9b0b1a7bf > --- /dev/null > +++ b/arch/arm64/include/asm/kvm_debug_buffer.h > @@ -0,0 +1,34 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * Copyright 2020 Google LLC > + * Author: George Popescu > + */ > +#ifndef __ASSEMBLY__ > + > +#include > +#include > + > +#ifdef __KVM_NVHE_HYPERVISOR__ > +#define DEFINE_KVM_DEBUG_BUFFER(type_name, buff_name, size) \ > + DEFINE_PER_CPU(type_name, buff_name)[(size)]; \ > + DEFINE_PER_CPU(unsigned long, buff_name##_wr_ind) = 0 > + > +#define DECLARE_KVM_DEBUG_BUFFER(type_name, buff_name, size) \ > + DECLARE_PER_CPU(type_name, buff_name)[(size)]; \ > + DECLARE_PER_CPU(unsigned long, buff_name##_wr_ind) > + > +#else > + > +#define DECLARE_KVM_DEBUG_BUFFER(type_name, buff_name, size) \ > + DECLARE_PER_CPU(type_name, kvm_nvhe_sym(buff_name))[(size)]; \ > + DECLARE_PER_CPU(unsigned long, kvm_nvhe_sym(buff_name##_wr_ind)) > +#endif //__KVM_NVHE_HYPERVISOR__ nit: comment style, here and below > + > +#else > + > +.macro clear_kvm_debug_buffer sym tmp1, tmp2, tmp3 > + mov \tmp1, 0 > + hyp_str_this_cpu \sym, \tmp1, \tmp2, \tmp3 > +.endm Can you can use xzr (zero register) directly rather than moving the constant 0 into a temporary? hyp_str_this_cpu \sym, xzr, \tmp1, \tmp2 > + > +#endif // __ASSEMBLY__ > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 905c2b87e05a..adc8957e9321 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -494,6 +494,10 @@ u64 __kvm_call_hyp(void *hypfn, ...); > __kvm_call_hyp(kvm_ksym_ref_nvhe(f), ##__VA_ARGS__); \ > }) > > +#define __kvm_arm_check_debug_buffer() \ > +{ \ > +} > + > /* > * The couple of isb() below are there to guarantee the same behaviour > * on VHE as on !VHE, where the eret to EL1 acts as a context > @@ -506,6 +510,7 @@ u64 __kvm_call_hyp(void *hypfn, ...); > isb(); \ > } else { \ > kvm_call_hyp_nvhe(f, ##__VA_ARGS__); \ > + __kvm_arm_check_debug_buffer(); \ > } \ > } while(0) > > @@ -518,6 +523,7 @@ u64 __kvm_call_hyp(void *hypfn, ...); > isb(); \ > } else { \ > ret = kvm_call_hyp_nvhe_ret(f, ##__VA_ARGS__); \ > + __kvm_arm_check_debug_buffer(); \ As Will was pointing out earlier, does the checking need to have preemption disabled in case there is another call into hyp that corrupts the buffer while it is being checked? > } \ > \ > ret; \ > diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S > index 46b4dab933d0..8df0082b9ccf 100644 > --- a/arch/arm64/kvm/hyp/hyp-entry.S > +++ b/arch/arm64/kvm/hyp/hyp-entry.S > @@ -68,7 +68,7 @@ el1_sync: // Guest trapped into EL2 > cbnz x1, el1_hvc_guest // called HVC > > /* Here, we're pretty sure the host called HVC. */ > - ldp x0, x1, [sp], #16 > + ldp x0, x1, [sp], #16 Is this a whitespace change? Maybe drop from this patch if it isn't related. > > /* Check for a stub HVC call */ > cmp x0, #HVC_STUB_HCALL_NR > -- > 2.28.0.618.gf4bc123cb7-goog >