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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 767EBC432BE for ; Sat, 31 Jul 2021 01:14:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5383860F48 for ; Sat, 31 Jul 2021 01:14:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234520AbhGaBO0 (ORCPT ); Fri, 30 Jul 2021 21:14:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33600 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231337AbhGaBOY (ORCPT ); Fri, 30 Jul 2021 21:14:24 -0400 Received: from mail-qv1-xf4a.google.com (mail-qv1-xf4a.google.com [IPv6:2607:f8b0:4864:20::f4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 97573C0613C1 for ; Fri, 30 Jul 2021 18:14:18 -0700 (PDT) Received: by mail-qv1-xf4a.google.com with SMTP id o32-20020a0c85a30000b0290328f91ede2bso7148784qva.1 for ; Fri, 30 Jul 2021 18:14:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=reply-to:date:message-id:mime-version:subject:from:to:cc; bh=Z+jBLOwaMHrD3vpQNOpOohSej7/a6ld7rbOxzY8Rd54=; b=KWHmbWUtKjbcYcQHomSb4B1ApPywDoaS8s42TLlijLflq4kD2tH8pFsodAT5RfVXdR YK0JWLwaaMRXDvEI/gVHQ6ZUswZh8yMStA1+5QeZCm0Po3n3pybFNfl6FzggLoyeY5Iv q/w9t0SvdIbOuoZx6uhxSF8YmjrGimgrVRlmpfEgm9MJUGEH1tdd/ywQ4ClR27guHbpe KWHEp/5x6YZ73mOuhFsGBYR+7R1MKA7K5qdR4iAMhUd5lBt9RboH+vjJOo8EMHr6QjLM cvfZ7eQTq/Hx5wS+ccpyJ/DgYwYTtk3oiJ+9QNbC86GkFU3Rzu5ELC8FfjSGTkhnIAK0 9gQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:reply-to:date:message-id:mime-version:subject :from:to:cc; bh=Z+jBLOwaMHrD3vpQNOpOohSej7/a6ld7rbOxzY8Rd54=; b=mXiB/Z4i5GtebQCNsWDA2Ei2Ils92lElJJMOKC9eLJtSMr5rOBjanm75ns+uhs7Ux4 G87PZ4vUSqEt9YgNbZQTz0oxdEK0Dk/noDMt6rRE/zV8R1myG5FIWmqXmt5Xe8PvENnp F1DMC5xkBk7VTIdkiR6S9NG/nXsZAIjE0aQw8xxb8SVfk9l8C+H9mnRJvIuWuxz9c9rN lvbcLRclmZCLGm2vDOCDnbco69DLoqKVVNfsD5WTxo5SjAes/UYMx+78UCvnt3HxFNIO zYM27NH9ke/1HakboClgflPZxTrTWYXLeK0p7HpJT/g1Za1eS4Z/Fq1gWtt3CP/bo62W h7PQ== X-Gm-Message-State: AOAM533irJMU+TTHjdS5At2gTVhDB5ZVaDCV90UmTa8PIJI005YG9gUV cvJ4br1uIIYdCAw7yvxCKFEASn3SYApG X-Google-Smtp-Source: ABdhPJzpDwuooUXZRIvdINIqPPnA6y1MqnCrAjWz5q0X22yWSn7QhNy6ZFuYNYPqDYYDEqNujWC9e4rza03J X-Received: from mihenry-linux-desktop.kir.corp.google.com ([2620:15c:29:204:a198:4c3e:b951:58e3]) (user=mizhang job=sendgmr) by 2002:a0c:ef4f:: with SMTP id t15mr5815346qvs.31.1627694057687; Fri, 30 Jul 2021 18:14:17 -0700 (PDT) Reply-To: Mingwei Zhang Date: Fri, 30 Jul 2021 18:13:04 -0700 Message-Id: <20210731011304.3868795-1-mizhang@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.32.0.554.ge1b32706d8-goog Subject: [PATCH] KVM: SEV: improve the code readability for ASID management From: Mingwei Zhang To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Mingwei Zhang , Tom Lendacky , Marc Orr , David Rientjes , Alper Gun , Dionna Glaze , Vipin Sharma Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KVM SEV code uses bitmaps to manage ASID states. ASID 0 was always skipped because it is never used by VM. Thus, ASID value and its bitmap postion always has an 'offset-by-1' relationship. Both SEV and SEV-ES shares the ASID space, thus KVM uses a dynamic range [min_asid, max_asid] to handle SEV and SEV-ES ASIDs separately. Existing code mixes the usage of ASID value and its bitmap position by using the same variable called 'min_asid'. Fix the min_asid usage: ensure that its usage is consistent with its name; adjust its value before using it as a bitmap position. Add comments on ASID bitmap allocation to clarify the skipping-ASID-0 property. Fixes: 80675b3ad45f (KVM: SVM: Update ASID allocation to support SEV-ES guests) Signed-off-by: Mingwei Zhang Cc: Tom Lendacky Cc: Marc Orr Cc: David Rientjes Cc: Alper Gun Cc: Dionna Glaze Cc: Sean Christopherson Cc: Vipin Sharma Ce: Peter Gonda --- arch/x86/kvm/svm/sev.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 8d36f0c73071..e3902283cbf7 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -80,7 +80,7 @@ static int sev_flush_asids(int min_asid, int max_asid) int ret, pos, error = 0; /* Check if there are any ASIDs to reclaim before performing a flush */ - pos = find_next_bit(sev_reclaim_asid_bitmap, max_asid, min_asid); + pos = find_next_bit(sev_reclaim_asid_bitmap, max_asid, min_asid - 1); if (pos >= max_asid) return -EBUSY; @@ -142,10 +142,10 @@ static int sev_asid_new(struct kvm_sev_info *sev) * SEV-enabled guests must use asid from min_sev_asid to max_sev_asid. * SEV-ES-enabled guest can use from 1 to min_sev_asid - 1. */ - min_asid = sev->es_active ? 0 : min_sev_asid - 1; + min_asid = sev->es_active ? 1 : min_sev_asid; max_asid = sev->es_active ? min_sev_asid - 1 : max_sev_asid; again: - pos = find_next_zero_bit(sev_asid_bitmap, max_sev_asid, min_asid); + pos = find_next_zero_bit(sev_asid_bitmap, max_sev_asid, min_asid - 1); if (pos >= max_asid) { if (retry && __sev_recycle_asids(min_asid, max_asid)) { retry = false; @@ -1854,7 +1854,10 @@ void __init sev_hardware_setup(void) min_sev_asid = edx; sev_me_mask = 1UL << (ebx & 0x3f); - /* Initialize SEV ASID bitmaps */ + /* + * Initialize SEV ASID bitmaps. Note: ASID 0 is skipped since it is + * never used by any VM, thus: ASID value == ASID position + 1; + */ sev_asid_bitmap = bitmap_zalloc(max_sev_asid, GFP_KERNEL); if (!sev_asid_bitmap) goto out; @@ -1904,7 +1907,7 @@ void sev_hardware_teardown(void) return; /* No need to take sev_bitmap_lock, all VMs have been destroyed. */ - sev_flush_asids(0, max_sev_asid); + sev_flush_asids(1, max_sev_asid); bitmap_free(sev_asid_bitmap); bitmap_free(sev_reclaim_asid_bitmap); -- 2.32.0.554.ge1b32706d8-goog