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 A8C9CC433F5 for ; Mon, 22 Nov 2021 17:02:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234367AbhKVRFL (ORCPT ); Mon, 22 Nov 2021 12:05:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233392AbhKVRFK (ORCPT ); Mon, 22 Nov 2021 12:05:10 -0500 Received: from mail-pl1-x631.google.com (mail-pl1-x631.google.com [IPv6:2607:f8b0:4864:20::631]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 54932C061714 for ; Mon, 22 Nov 2021 09:02:04 -0800 (PST) Received: by mail-pl1-x631.google.com with SMTP id p18so14609539plf.13 for ; Mon, 22 Nov 2021 09:02:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=MMxdg/i4Tpz0Ny0YKb9MupTTV7gYPwcXTsq8GtgzJuM=; b=DgZvD0GvFzjj73SoxWOTrAHZamGw2+U8sYNs3o49VVo7sfv9huDqh/8GqI0aBC+3em aN7WO1s5yp2tqrb41phNL5UtZArhcUYk4U1CgJzKK/OM2P/YF0qb/Obsy5ElVLQXbYaZ WoyvkgOZV/9xySMvcRDmFKs6Fk9Wo1T2vlciBvNXOMviYXrS+5tnVrwtbwAPUBKVngB0 JMbUUX0ENnuVXjiR+H7dJQzLaI08CAhvM5PFzGNte+H61/D9wlDdOeqrcKcDpjKvkxxD NbKZ4ZpPUCpxckkRSf9cH9aj/2HT9fargjlxaDp1GRUUBvaigw1InCuDevQ/PJLUsz9a YNMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=MMxdg/i4Tpz0Ny0YKb9MupTTV7gYPwcXTsq8GtgzJuM=; b=W6mO0qFqkAilbg08bla/98ZdRbZ/2SIsZcdQkxnoJHeRO4mcRHNeXrnRXY7I5H9Emj TZGDmd90YbCZ1xTRb616Q603Uz0LTta57z7AcK9kECsvwGTG/LbRBVQjRexHfUqXfPBd 3In8XSAow7kQL6zxFhHDmluZGmTHH4bn74WRNpA8FPndZN2v0MXN1Tjdr+YZ/3omLOQt mUosWuSSPXKl5bcyduv4XLIDRnXMTCIIpBNa9a091XVWWgiBOJ+ps6DgsRP4sRiY6hux lVUmw8QydWBLYbyNUp8hMJIECAoyetrGZMO1xGdNKYu8SuU1uX4Ic0NI83nG5+38Egke pn4A== X-Gm-Message-State: AOAM531L72m4BUrjH0uxn2T/msS64uHs2AfKw2vEfEUkbKYKcH9+h6UI 7jfEglMnxWwzy30/4QvbB/pp7Q== X-Google-Smtp-Source: ABdhPJwsBA16xCRHpsoGuZDsd5cSfRiEfUXusyWpAfQEfVu8E/Lqs/AD7msOa3WreFEUhY9W5jrmtQ== X-Received: by 2002:a17:90b:3142:: with SMTP id ip2mr33377297pjb.207.1637600523578; Mon, 22 Nov 2021 09:02:03 -0800 (PST) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id me7sm21954801pjb.9.2021.11.22.09.02.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Nov 2021 09:02:02 -0800 (PST) Date: Mon, 22 Nov 2021 17:01:59 +0000 From: Sean Christopherson To: David Woodhouse Cc: Paolo Bonzini , butt3rflyh4ck , kvm@vger.kernel.org, LKML Subject: Re: KVM: Warn if mark_page_dirty() is called without an active vCPU Message-ID: References: <9eb83cdd-9314-0d1f-0d4b-0cf4432e1e84@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Sat, Nov 20, 2021, David Woodhouse wrote: > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 6c5083f2eb50..72c6453bcef4 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -3020,12 +3020,17 @@ void mark_page_dirty_in_slot(struct kvm *kvm, > struct kvm_memory_slot *memslot, > gfn_t gfn) > { > + struct kvm_vcpu *vcpu = kvm_get_running_vcpu(); > + > + if (WARN_ON_ONCE(!vcpu) || WARN_ON_ONCE(vcpu->kvm != kvm)) Maybe use KVM_BUG_ON? And two separate WARNs are probably overkill. if (KVM_BUG_ON(!vcpu || vcpu->kvm != kvm, kvm)) I'd also prefer to not retrieve the vCPU in the dirty_bitmap path, at least not until it's necessary (for the proposed dirty quota throttling), though that's not a strong preference. > + return; > + > if (memslot && kvm_slot_dirty_track_enabled(memslot)) { > unsigned long rel_gfn = gfn - memslot->base_gfn; > u32 slot = (memslot->as_id << 16) | memslot->id; > > if (kvm->dirty_ring_size) > - kvm_dirty_ring_push(kvm_dirty_ring_get(kvm), > + kvm_dirty_ring_push(&vcpu->dirty_ring, > slot, rel_gfn); This can now squeeze on a single line. kvm_dirty_ring_push(&vcpu->dirty_ring, slot, rel_gfn); > else > set_bit_le(rel_gfn, memslot->dirty_bitmap); > -- > 2.31.1 >