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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AAC5BC04A94 for ; Tue, 15 Aug 2023 22:30:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240201AbjHOWaU (ORCPT ); Tue, 15 Aug 2023 18:30:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240276AbjHOWaN (ORCPT ); Tue, 15 Aug 2023 18:30:13 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 115791FEE for ; Tue, 15 Aug 2023 15:30:11 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-d65201b777dso10327430276.0 for ; Tue, 15 Aug 2023 15:30:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1692138610; x=1692743410; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=1sZ2KVcNcsekfiyOLDchFCWiNwVhcB+6K151wSFXsRU=; b=Sdk8hg1CZo0UZyPRUXVdkK75UBWBJbL5ssV4qfSNcJ0yLv5eoBjQS4ikTylrgvjRg5 fAMh6d0O8KCRFHTNCYjLyKwda9Worh9IOHwLdjyjr43jpwYw1T/I0j2MIMowNRlDO5I8 seJUbGeGRi1534R52LzEYYDDd5ijl0Ycakp7SKP7ACJxBKwO5q+1sd6EI3OyWGK24CgX jnL6doBdY30gIbx8RPMUELSJ79bpzsOBy12TJfrWjd52P0gtLnjQyB6B7osJCqozOqtW mlUSNNG5Lq0KPPvS7OkMRg41GasfSw3x8Ne19ql/oMstCF4KKqyTw1HO8U30XcK6asyE 9NgQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692138610; x=1692743410; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=1sZ2KVcNcsekfiyOLDchFCWiNwVhcB+6K151wSFXsRU=; b=Kk6tz0xDzevZNV22zK5TBTlr+53qTyXGMG8/DpfIc2yzhsw7dclKSNKx0X7jsalEaG ZNqP2deXJs8ns+OE0dFrwbJbe7azgDEYBQ9qlvsrgWbpVoBEFi7I/tQ2yq8lZTTDV38t 7mPY0gTHimfjuAQUT/w0j0+QXoXsVKXHQBS72ow6BYxxL9+3pAlx+xbX6tkRwonZb7XS fiuuQ80kRpd+rsI6cKUrhZUmC9NXY+87P57aes6hV8tb1CdKHibXFWbe89jT09tGD0lP t+P9OiNrEwD6cE/RR4Q3Um8Ih+ZD8j120XXqLR36FKP/CGfJQ5ZyPKRUp8heXdWSoiPa cV2A== X-Gm-Message-State: AOJu0Yz+EbQYRGpjbVwBC7en9tF40LbpeCe0H2rTSRN6hvMTjQDm7uys OSyO1vTe/PScLHjShk7/Hc6GfL+znTw= X-Google-Smtp-Source: AGHT+IG84S1z3EOk6278E7swEnxMzcYiiiMN3uMBAf/Zzr7Ij9WLl4fIHdZlEc+ZYkT7nZQXafm39o4AAu0= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:24cc:0:b0:d10:a33d:36b6 with SMTP id k195-20020a2524cc000000b00d10a33d36b6mr55769ybk.0.1692138610358; Tue, 15 Aug 2023 15:30:10 -0700 (PDT) Date: Tue, 15 Aug 2023 15:30:08 -0700 In-Reply-To: <20230811045127.3308641-6-rananta@google.com> Mime-Version: 1.0 References: <20230811045127.3308641-1-rananta@google.com> <20230811045127.3308641-6-rananta@google.com> Message-ID: Subject: Re: [PATCH v9 05/14] KVM: Allow range-based TLB invalidation from common code From: Sean Christopherson To: Raghavendra Rao Ananta Cc: Oliver Upton , Marc Zyngier , James Morse , Suzuki K Poulose , Paolo Bonzini , Huacai Chen , Zenghui Yu , Anup Patel , Atish Patra , Jing Zhang , Reiji Watanabe , Colton Lewis , David Matlack , Fuad Tabba , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Gavin Shan , Shaoqin Huang Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Fri, Aug 11, 2023, Raghavendra Rao Ananta wrote: > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index ec169f5c7dce2..00f7bda9202f2 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -278,16 +278,14 @@ static inline bool kvm_available_flush_remote_tlbs_range(void) > return kvm_x86_ops.flush_remote_tlbs_range; > } > > -void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn, > - gfn_t nr_pages) > +int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm, gfn_t gfn, u64 nr_pages) > { > int ret = -EOPNOTSUPP; > > if (kvm_x86_ops.flush_remote_tlbs_range) > - ret = static_call(kvm_x86_flush_remote_tlbs_range)(kvm, start_gfn, > - nr_pages); > - if (ret) > - kvm_flush_remote_tlbs(kvm); > + ret = static_call(kvm_x86_flush_remote_tlbs_range)(kvm, gfn, nr_pages); > + > + return ret; Please write this as if (kvm_x86_ops.flush_remote_tlbs_range) return static_call(kvm_x86_flush_remote_tlbs_range)(kvm, gfn, nr_pages); return -EOPNOTSUPP; or alternatively if (!kvm_x86_ops.flush_remote_tlbs_range) return -EOPNOTSUPP; return static_call(kvm_x86_flush_remote_tlbs_range)(kvm, gfn, nr_pages); Hmm, I'll throw my official vote for the second version. The local "ret" is unnecessary and is suprisingly dangerous. I screwed up the conflict resolution when cherry-picking my CONFIG_HYPERV change to see what the conflict looked like and ended up with a double flush: int ret = -EOPNOTSUPP; if (kvm_x86_ops.flush_remote_tlbs_range) ret = static_call(kvm_x86_flush_remote_tlbs_range)(kvm, gfn, nr_pages); if (ret) kvm_flush_remote_tlbs(kvm); return ret; Dropping "ret" makes it much harder to get trigger happy when resolving conflicts. No need for a new version to fix the above, assuming Marc/Oliver is ok doing fixup when applying. Nit aside, looks good for x86, and I know of no conflicts, so take 'er away! Acked-by: Sean Christopherson