From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 773BF20B0A for ; Mon, 18 Sep 2023 15:52:42 +0000 (UTC) Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-1c448ba292dso18243015ad.3 for ; Mon, 18 Sep 2023 08:52:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1695052362; x=1695657162; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=2U3xsG0fg5xdFpPmP8zowhEzmg+gfxwbZh9hlXMaF+c=; b=awrSp3q72Hy7bQSMm/OzE+g0LSKiE08dBUB1f8Vqr7dEzdGpbRkpeSJ7cQ2DKSP6Tu hlH1Yt1HmiNbVkh1i1xRxCyA7h5DC0BtqZGmeH1du17nRM3JB9Zh1wrdRoCr1yO6Gh5s HZvhunSXRjdplBftlFpWIxW4Oezv/D+H8itgGGDSVMJ735jUHlwqE5uXZo0VIdx5vxIk Is6EehfsC9WzTwPcMv3A1MaimP2wrWYkxT1Xh2UJVpMgvZ6Wh8+vT7ZjvKTMMfsuxjFx cDUDzyososBiul3bq5mpabU3ys/eL93uhgeeIjQ5SvFw9VMxoem9VXiIFaLl/fnT30xD 4U+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695052362; x=1695657162; 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=2U3xsG0fg5xdFpPmP8zowhEzmg+gfxwbZh9hlXMaF+c=; b=Cj09l3k7DkSKGOcvJqH1NEGLTWZk9b4bwD/XV6HQ1mzdTyZGLzDPNd2gMokFh2rrqK 3KFqDtq8OIbfeDQYzw7w6Efhgt6wzfqrUuylOfwjeA6qhiNbdPjAsHF3NdLax43riOZS gC/sHIojKzNYGpaAY4VDwMj0647vU19FbvlovmyCLvAtQmQzOHToGLsDdtOVmyrK1PLA GCh55wY5GiCqc9mooj5h7lpGn1sqxi1M4Vmg3BRPJJjM+ZZ3v+dprkhw3iEOqH80RlXs OFA7wp3MezeYkl0ZKdkA2jToch1AEoIH6YWiSM1OZEtrTYkD0bRoOJ91/qwsd0LnpHTd tByg== X-Gm-Message-State: AOJu0YwTbmdw226bUGx8WHWjJ/e3KmpI/+1Dp5Dna7wOx0bmxkoccH2Y 2c0/gk7ROEojjFW7AlgmeymNKpC6ET4= X-Google-Smtp-Source: AGHT+IGgNS2Vz9a89mB0wnbmpqOo9ipRBHkgWDp+LBnX1+UB/D0eQmGLqC9so7UJgprSn2d6kzcCXv9BIzw= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:903:41c2:b0:1c1:fbec:bc39 with SMTP id u2-20020a17090341c200b001c1fbecbc39mr210522ple.4.1695052361665; Mon, 18 Sep 2023 08:52:41 -0700 (PDT) Date: Mon, 18 Sep 2023 08:52:40 -0700 In-Reply-To: <20230918152946.GJ13795@ziepe.ca> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20230916003118.2540661-1-seanjc@google.com> <20230916003118.2540661-7-seanjc@google.com> <20230918152946.GJ13795@ziepe.ca> Message-ID: Subject: Re: [PATCH 06/26] KVM: Drop CONFIG_KVM_VFIO and just look at KVM+VFIO From: Sean Christopherson To: Jason Gunthorpe Cc: Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Peter Zijlstra , Arnaldo Carvalho de Melo , Paolo Bonzini , Tony Krowiak , Halil Pasic , Jason Herne , Harald Freudenberger , Alex Williamson , Andy Lutomirski , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, kvm@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Anish Ghulati , Venkatesh Srinivas , Andrew Thornton Content-Type: text/plain; charset="us-ascii" On Mon, Sep 18, 2023, Jason Gunthorpe wrote: > On Fri, Sep 15, 2023 at 05:30:58PM -0700, Sean Christopherson wrote: > > Drop KVM's KVM_VFIO Kconfig, and instead compile in VFIO support if > > and only if VFIO itself is enabled. Similar to the recent change to have > > VFIO stop looking at HAVE_KVM, compiling in support for talking to VFIO > > just because the architecture supports VFIO is nonsensical. > > > > This fixes a bug where RISC-V doesn't select KVM_VFIO, i.e. would silently > > fail to do connect KVM and VFIO, even though RISC-V supports VFIO. The > > bug is benign as the only driver in all of Linux that actually uses the > > KVM reference provided by VFIO is KVM-GT, which is x86/Intel specific. > > Hmm, I recall that all the S390 drivers need it as well. > > static int vfio_ap_mdev_open_device(struct vfio_device *vdev) > { > struct ap_matrix_mdev *matrix_mdev = > container_of(vdev, struct ap_matrix_mdev, vdev); > > if (!vdev->kvm) > return -EINVAL; > > return vfio_ap_mdev_set_kvm(matrix_mdev, vdev->kvm); Ah, I missed that the KVM reference was routed through VFIO in that case. > I wonder if we should be making the VFIO drivers that need the kvm to > ask for it? 'select CONFIG_NEED_VFIO_KVM' or something? I wondered the same thing, if only to make it easier to track which drivers actually end up interacting directly with KVM. > Regardless, I fully agree with getting rid of the arch flag. > > Reviewed-by: Jason Gunthorpe > > > --- a/virt/kvm/Makefile.kvm > > +++ b/virt/kvm/Makefile.kvm > > @@ -6,7 +6,9 @@ > > KVM ?= ../../../virt/kvm > > > > kvm-y := $(KVM)/kvm_main.o $(KVM)/eventfd.o $(KVM)/binary_stats.o > > -kvm-$(CONFIG_KVM_VFIO) += $(KVM)/vfio.o > > +ifdef CONFIG_VFIO > > +kvm-y += $(KVM)/vfio.o > > +endif > > I wonder if kvm-m magically works in kbuild so you don't need the ifdef? Yeah, that should work, no idea why I added the ifdef.