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=-26.2 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 BAE15C432BE for ; Mon, 2 Aug 2021 18:09:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9F6DF60EE3 for ; Mon, 2 Aug 2021 18:09:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230262AbhHBSJq (ORCPT ); Mon, 2 Aug 2021 14:09:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48086 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229537AbhHBSJp (ORCPT ); Mon, 2 Aug 2021 14:09:45 -0400 Received: from mail-pj1-x1049.google.com (mail-pj1-x1049.google.com [IPv6:2607:f8b0:4864:20::1049]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3B78C061760 for ; Mon, 2 Aug 2021 11:09:34 -0700 (PDT) Received: by mail-pj1-x1049.google.com with SMTP id h21-20020a17090adb95b029017797967ffbso706611pjv.5 for ; Mon, 02 Aug 2021 11:09:34 -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=zTp4k8EQSXsCqyOFWmBzNmeaus4lIgrrLbtUHvM24/g=; b=qhcqAy6X0f6Y4aR8jJOiOx4TnSaoAruw6C3jfL3ikjsiEwDF6eTx4VMr0NqBUhj2yn ZoR/Ap4h3eLc7gg2h1Ua5DRcmIe4d1IQVxPJnrNsdhUporMIVMu1t8cb3F9sCckTVvRO dka5xyl6fGQHdSwKX64hZ8OdZFLJ22L8H+5+ZMQ+vN/OlKfRzobbZTFY7fykAHqgel2K SLJ/eOtlOBeWw+PKxO9k9hU/+t9ni/nH/C/i9sYzOSOhdK946e0nSAmCkU+DLEunzt+X k56MXpjljwBiZQlq2usN9kQx3sMo3cqBIoYHM5WiLWkk1cg3u1j6QZLdMqsl7TKeYEje 1frw== 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=zTp4k8EQSXsCqyOFWmBzNmeaus4lIgrrLbtUHvM24/g=; b=OP1aOwPClBggAzzrezZEXSY3BGv6vWWjxX6gyAnZLjCP9TNlqp1iptJlFZ54ws9plm OEP+5JTCN6VE0AgzL8DRmwjLUTcG9XhWvhss/c0lwiYwnpL4hivASTS0LfZkYF0oXRdJ +5rEMQoenzdyNwXoRNJjnvDnYbpDKoaKGF9XHSyfy3crIJjRxLYkcAmAiHw/8dwazO8Y yFpuff/zvvHOjPvNOXcQyJ4aCR8XLnPi5q2N8tPe1yNz+Xq771ywTEObif79xD8pvWdF Q2X0i/MjHn9qc8Q7P/dLI+H5gd1cnU8+b1Jn+O9IHvHqEK7Ckb6Wu5i8GKAHK6tPEFOw KpBg== X-Gm-Message-State: AOAM533xQ78tWxey1YwQ55kunezQBuNXQL9H7HIoWsaSOIE5cseRfM5C 4/BPxc26pCL7GRtj0pXCXI2QMABk7JLX X-Google-Smtp-Source: ABdhPJypTOGt3dVr7WRDACS04dVkLBGgCfDe22b6WkTs8J473eGM4W+aAkmCJ6G5w3QXiYsAJj/qWalIBpNE X-Received: from mihenry-linux-desktop.kir.corp.google.com ([2620:15c:29:204:4304:2e3e:d2f5:48c8]) (user=mizhang job=sendgmr) by 2002:a05:6a00:1245:b029:30f:2098:fcf4 with SMTP id u5-20020a056a001245b029030f2098fcf4mr17867197pfi.66.1627927774160; Mon, 02 Aug 2021 11:09:34 -0700 (PDT) Reply-To: Mingwei Zhang Date: Mon, 2 Aug 2021 11:09:03 -0700 Message-Id: <20210802180903.159381-1-mizhang@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.32.0.554.ge1b32706d8-goog Subject: [PATCH v2] KVM: SVM: 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 , Peter Gonda 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, in existing code, 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; allocate extra size for ASID 0 to ensure that each ASID has the same value with its bitmap position. Add comments on ASID bitmap allocation to clarify the size change. v1 -> v2: - change ASID bitmap size to incorporate ASID 0 [sean] - remove the 'fixes' line in commit message. [sean/joerg] 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 Cc: Peter Gonda Cc: Joerg Roedel --- arch/x86/kvm/svm/sev.c | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 8d36f0c73071..42d46c30f313 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -63,6 +63,7 @@ static DEFINE_MUTEX(sev_bitmap_lock); unsigned int max_sev_asid; static unsigned int min_sev_asid; static unsigned long sev_me_mask; +static unsigned int nr_asids; static unsigned long *sev_asid_bitmap; static unsigned long *sev_reclaim_asid_bitmap; @@ -77,11 +78,11 @@ struct enc_region { /* Called with the sev_bitmap_lock held, or on shutdown */ static int sev_flush_asids(int min_asid, int max_asid) { - int ret, pos, error = 0; + int ret, asid, 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); - if (pos >= max_asid) + asid = find_next_bit(sev_reclaim_asid_bitmap, nr_asids, min_asid); + if (asid > max_asid) return -EBUSY; /* @@ -114,15 +115,15 @@ static bool __sev_recycle_asids(int min_asid, int max_asid) /* The flush process will flush all reclaimable SEV and SEV-ES ASIDs */ bitmap_xor(sev_asid_bitmap, sev_asid_bitmap, sev_reclaim_asid_bitmap, - max_sev_asid); - bitmap_zero(sev_reclaim_asid_bitmap, max_sev_asid); + nr_asids); + bitmap_zero(sev_reclaim_asid_bitmap, nr_asids); return true; } static int sev_asid_new(struct kvm_sev_info *sev) { - int pos, min_asid, max_asid, ret; + int asid, min_asid, max_asid, ret; bool retry = true; enum misc_res_type type; @@ -142,11 +143,11 @@ 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); - if (pos >= max_asid) { + asid = find_next_zero_bit(sev_asid_bitmap, max_sev_asid, min_asid); + if (asid > max_asid) { if (retry && __sev_recycle_asids(min_asid, max_asid)) { retry = false; goto again; @@ -156,11 +157,11 @@ static int sev_asid_new(struct kvm_sev_info *sev) goto e_uncharge; } - __set_bit(pos, sev_asid_bitmap); + __set_bit(asid, sev_asid_bitmap); mutex_unlock(&sev_bitmap_lock); - return pos + 1; + return asid; e_uncharge: misc_cg_uncharge(type, sev->misc_cg, 1); put_misc_cg(sev->misc_cg); @@ -1854,12 +1855,17 @@ void __init sev_hardware_setup(void) min_sev_asid = edx; sev_me_mask = 1UL << (ebx & 0x3f); - /* Initialize SEV ASID bitmaps */ - sev_asid_bitmap = bitmap_zalloc(max_sev_asid, GFP_KERNEL); + /* + * Initialize SEV ASID bitmaps. Allocate space for ASID 0 in the bitmap, + * even though it's never used, so that the bitmap is indexed by the + * actual ASID. + */ + nr_asids = max_sev_asid + 1; + sev_asid_bitmap = bitmap_zalloc(nr_asids, GFP_KERNEL); if (!sev_asid_bitmap) goto out; - sev_reclaim_asid_bitmap = bitmap_zalloc(max_sev_asid, GFP_KERNEL); + sev_reclaim_asid_bitmap = bitmap_zalloc(nr_asids, GFP_KERNEL); if (!sev_reclaim_asid_bitmap) { bitmap_free(sev_asid_bitmap); sev_asid_bitmap = NULL; @@ -1904,7 +1910,7 @@ 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