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 F416AC433F5 for ; Wed, 30 Mar 2022 16:43:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348895AbiC3QpC (ORCPT ); Wed, 30 Mar 2022 12:45:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233326AbiC3Qo4 (ORCPT ); Wed, 30 Mar 2022 12:44:56 -0400 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D44641BE4CF for ; Wed, 30 Mar 2022 09:43:10 -0700 (PDT) Received: by mail-pf1-x449.google.com with SMTP id x186-20020a627cc3000000b004fa939658c5so12299383pfc.4 for ; Wed, 30 Mar 2022 09:43:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc :content-transfer-encoding; bh=5nXtXrVSYraXOswJ0un7Hm7h4MEowJ6UqwfZSK0k/Ho=; b=KeiIrhzTnbxNfQgZB940dzCguVNEiqsc5GU+Ia3dHTg9v3MLhmKmLclbWTPEPhRjQc Yw6Nhb7RjuYwA3ku+Zn6mwKzTJcgxXWnoytSqvgaXKw9zytgardjMdoiv99jWNUI6Kew oelbriE/+VtiBlvubit/TXo9yVqGra5BJR9qTpDpASIrEfFBRFRf+wWzAmMt16cIn2zR Ds4qpj7JKOIq9+hhwoMoGw5gh3ucoS3YqrWjbj3EP7IbYMB4WdHEAj3JAF5xKbCBcfRf k78SJvN9EH5cE4tDT1w75vjwrCa1R4oU0BAUrl6C6sKNem5qu2Dm5uBdwyilOwo6ifNp uDqw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc :content-transfer-encoding; bh=5nXtXrVSYraXOswJ0un7Hm7h4MEowJ6UqwfZSK0k/Ho=; b=LW4fRDe7QF0It27/prgv3160w/6hJ16fZSG7kgfcQE12cXiTdEdcipNhpJnAgYmyBx PQJnvyIldZCH+XaMG5Iq/74hFbHTCjoWtuWVDRCFCjCyyK1fPdk+4hAu0dj+P0dNYlyd O35lXuB1LCmHtajt9Bu5mlrO/aYYpKTgbA+2stwPlrZuz4g7sxfBWhf9n9SE/jdSANk8 FxJcMVjMWCF2HRpaxWLrLIJ1a3JLbtxnElAdpL7LfbiUtWJCV7T+DkBXx/Xjx0rH+Gjq z5G/Fi7PqKvLWtzwvkFBi9xTqdbABp4E5daBm8cwBXuU1qOGaJe8rFL15Q73GxM3K01r NtQQ== X-Gm-Message-State: AOAM533y5abGdHNOGtF7IbiKbcdYBJq4CKq0xbprBuAT2OcONwbeA6Sp dB6G/uts9aJk8dsogiDs/PFO8JKKP/E= X-Google-Smtp-Source: ABdhPJwcTlkloq4QtJPS4G/HHgbttrIqnocT95vp1xV2O3KKx7i5gdZX29AMHSrnOU+jzj+SLb5cPdIUXUo= X-Received: from pgonda1.kir.corp.google.com ([2620:15c:29:203:94cc:eed1:3c93:b600]) (user=pgonda job=sendgmr) by 2002:a17:902:c2d8:b0:154:b384:917b with SMTP id c24-20020a170902c2d800b00154b384917bmr216875pla.58.1648658590332; Wed, 30 Mar 2022 09:43:10 -0700 (PDT) Date: Wed, 30 Mar 2022 09:43:06 -0700 Message-Id: <20220330164306.2376085-1-pgonda@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.35.1.1094.g7c7d902a7c-goog Subject: [PATCH] KVM: SEV: Add cond_resched() to loop in sev_clflush_pages() From: Peter Gonda To: kvm@vger.kernel.org Cc: Peter Gonda , Sean Christopherson , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add resched to avoid warning from sev_clflush_pages() with large number of pages. Signed-off-by: Peter Gonda Cc: Sean Christopherson Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- Here is a warning similar to what I've seen many times running large SEV VMs: [ 357.714051] CPU 15: need_resched set for > 52000222 ns (52 ticks) withou= t schedule [ 357.721623] WARNING: CPU: 15 PID: 35848 at kernel/sched/core.c:3733 sche= duler_tick+0x2f9/0x3f0 [ 357.730222] Modules linked in: kvm_amd uhaul vfat fat hdi2_standard_ftl = hdi2_megablocks hdi2_pmc hdi2_pmc_eeprom hdi2 stg elephant_dev_num ccp i2c_= mux_ltc4306 i2c_mux i2c_via_ipmi i2c_piix4 google_bmc_usb google_bmc_gpioi2= c_mb_common google_bmc_mailbox cdc_acm xhci_pci xhci_hcd sha3_generic gq nv= _p2p_glue accel_class [ 357.758261] CPU: 15 PID: 35848 Comm: switchto-defaul Not tainted 4.15.0-= smp-DEV #11 [ 357.765912] Hardware name: Google, Inc. = Arcadia_IT_80/Arcadia_IT_80, BIOS 30.20.2-gce 11/05/2= 021 [ 357.779372] RIP: 0010:scheduler_tick+0x2f9/0x3f0 [ 357.783988] RSP: 0018:ffff98558d1c3dd8 EFLAGS: 00010046 [ 357.789207] RAX: 741f23206aa8dc00 RBX: 0000005349236a42 RCX: 00000000000= 00007 [ 357.796339] RDX: 0000000000000006 RSI: 0000000000000002 RDI: ffff98558d1= d5a98 [ 357.803463] RBP: ffff98558d1c3ea0 R08: 0000000000100ceb R09: 00000000000= 00000 [ 357.810597] R10: ffff98558c958c00 R11: ffffffff94850740 R12: 00000000031= 975de [ 357.817729] R13: 0000000000000000 R14: ffff98558d1e2640 R15: ffff9852573= 9ea40 [ 357.824862] FS: 00007f87503eb700(0000) GS:ffff98558d1c0000(0000) knlGS:= 0000000000000000 [ 357.832948] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 357.838695] CR2: 00005572fe74b080 CR3: 0000007bea706006 CR4: 00000000003= 60ef0 [ 357.845828] Call Trace: [ 357.848277] [ 357.850294] [] ? tick_setup_sched_timer+0x130/0x130 [ 357.856818] [] ? rcu_sched_clock_irq+0x6ed/0x850 [ 357.863084] [] ? __run_timers+0x42/0x260 [ 357.868654] [] ? tick_setup_sched_timer+0x130/0x130 [ 357.875182] [] update_process_times+0x7b/0x90 [ 357.881188] [] tick_sched_timer+0x82/0xd0 [ 357.886845] [] __run_hrtimer+0x81/0x200 [ 357.892331] [] hrtimer_interrupt+0x192/0x450 [ 357.898252] [] ? __do_softirq+0x2fa/0x33e [ 357.903911] [] smp_apic_timer_interrupt+0xac/0x1d0 [ 357.910349] [] apic_timer_interrupt+0x86/0x90 [ 357.916347] [ 357.918452] RIP: 0010:clflush_cache_range+0x3f/0x50 [ 357.923324] RSP: 0018:ffff98529af89cc0 EFLAGS: 00000246 ORIG_RAX: ffffff= ffffffff12 [ 357.930889] RAX: 0000000000000040 RBX: 0000000000038135 RCX: ffff985233d= 36000 [ 357.938013] RDX: ffff985233d36000 RSI: 0000000000001000 RDI: ffff985233d= 35000 [ 357.945145] RBP: ffff98529af89cc0 R08: 0000000000000001 R09: ffffb5753fb= 23000 [ 357.952271] R10: 000000000003fe00 R11: 0000000000000008 R12: 00000000000= 40000 [ 357.959401] R13: ffff98525739ea40 R14: ffffb5753fb22000 R15: ffff98532a5= 8dd80 [ 357.966536] [] svm_register_enc_region+0xd1/0x170 [kv= m_amd] [ 357.973758] [] kvm_arch_vm_ioctl+0x84c/0xb00 [ 357.979677] [] ? handle_mm_fault+0x6ff/0x1370 [ 357.985683] [] kvm_vm_ioctl+0x69b/0x720 [ 357.991167] [] do_vfs_ioctl+0x47d/0x680 [ 357.996654] [] SyS_ioctl+0x68/0x90 [ 358.001706] [] do_syscall_64+0x71/0x110 [ 358.007192] [] entry_SYSCALL_64_after_hwframe+0x3d/0x= a2 Tested by running a large 256gib SEV VM several times, saw no warnings. Without the change warnings are seen. --- arch/x86/kvm/svm/sev.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 75fa6dd268f0..c2fe89ecdb2d 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -465,6 +465,7 @@ static void sev_clflush_pages(struct page *pages[], uns= igned long npages) page_virtual =3D kmap_atomic(pages[i]); clflush_cache_range(page_virtual, PAGE_SIZE); kunmap_atomic(page_virtual); + cond_resched(); } } =20 --=20 2.35.1.1094.g7c7d902a7c-goog