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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED346C433F5 for ; Wed, 17 Nov 2021 17:19:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C97676137B for ; Wed, 17 Nov 2021 17:19:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239180AbhKQRWB (ORCPT ); Wed, 17 Nov 2021 12:22:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39832 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229585AbhKQRWA (ORCPT ); Wed, 17 Nov 2021 12:22:00 -0500 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22B5BC061570 for ; Wed, 17 Nov 2021 09:19:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=MIME-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=NeUEfrnNQuo19v3peXb6El/qDz/czSJ2oO4GvvOEZVc=; b=YKxdWIKtBiEQypUMauCB33a8rX SPARezj/MvmgWmIFbmXv/A3IxMQcj4MweXWgDZc7WxbIcpOalc/BrpZHYdQDj+rfiarzedY6lMRk2 E4nP6HZsDM690xIKMo3RJDVG54vgL4UaeGLhk14w/lO3mNIiBVaejoneoY6Z1P0mr4+UTeRCVN1Q+ 460WCKquse6c4XYbYTsy2jSzRAhXq47ZMhfpNd0VYJ4GwtNOZx24dQBhrq+9W4I7pPvLCoPVNxNsK wyCIejAHKcQC7GrCk8njx+4w/5VJoRYumkXJllkQbJ3jOmK3Uy6qtwcbFANnhX1p9W2L4T2aY/AiA qaoNRpqg==; Received: from [2001:8b0:10b:1:4a2a:e3ff:fe14:8625] (helo=u3832b3a9db3152.ant.amazon.com) by bombadil.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mnOaC-005pJs-V8; Wed, 17 Nov 2021 17:18:53 +0000 Message-ID: <039d419a9a7b4995d153193962b2ce23915a127b.camel@infradead.org> Subject: Re: [PATCH 08/11] KVM: Kill kvm_map_gfn() / kvm_unmap_gfn() and gfn_to_pfn_cache From: David Woodhouse To: Paolo Bonzini , kvm Cc: Boris Ostrovsky , Joao Martins , "jmattson @ google . com" , "wanpengli @ tencent . com" , "seanjc @ google . com" , "vkuznets @ redhat . com" , "mtosatti @ redhat . com" , "joro @ 8bytes . org" , karahmed@amazon.com Date: Wed, 17 Nov 2021 17:18:50 +0000 In-Reply-To: References: <95fae9cf56b1a7f0a5f2b9a1934e29e924908ff2.camel@infradead.org> <20211115165030.7422-1-dwmw2@infradead.org> <20211115165030.7422-8-dwmw2@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-OEs2MkgXR/tbJE3pz7Kj" User-Agent: Evolution 3.36.5-0ubuntu1 MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org --=-OEs2MkgXR/tbJE3pz7Kj Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2021-11-16 at 11:21 +0100, Paolo Bonzini wrote: >=20 > Queued patches 2-8 as well. Thanks. These finally made it out to git.kernel.org and I see one of them has been afflicted by mojibake. commit d79f9da821fda5cbc5383a2d9b16a12c962cb772 Author: David Woodhouse Date: Mon Nov 15 16:50:27 2021 +0000 KVM: Kill kvm_map_gfn() / kvm_unmap_gfn() and gfn_to_pfn_cache =20 In commit 7e2175ebd695 ("KVM: x86: Fix recording of guest steal time / preempted status") I removed the only user of these functions because it was basically impossible to use them safely. =20 There are two stages to the GFN =C3=A2=E2=80=A0=E2=80=99 PFN mapping; f= irst through the KVM memslots to a userspace HVA and then through the page tables to translate that HVA to an underlying PFN. Invalidations of the former were being handled correctly, but no attempt was made to use the MMU notifiers to invalidate the cache when the HVA=C3=A2=E2=80=A0=E2=80=99G= FN mapping changed. =20 As a prelude to reinventing the gfn_to_pfn_cache with more usable semantics, rip it out entirely and untangle the implementation of the unsafe kvm_vcpu_map()/kvm_vcpu_unmap() functions from it. =20 All current users of kvm_vcpu_map() also look broken right now, and will be dealt with separately. They broadly fall into two classes: =20 =C3=A2=E2=82=AC=C2=A2 Those which map, access the data and immediately= unmap. This is mostly gratuitous and could just as well use the existing user HVA, and could probably benefit from a gfn_to_hva_cache as they do so. =20 =C3=A2=E2=82=AC=C2=A2 Those which keep the mapping around for a longer= time, perhaps even using the PFN directly from the guest. These will need to be converted to the new gfn_to_pfn_cache and then kvm_vcpu_map() can be removed too. =20 Signed-off-by: David Woodhouse Message-Id: <20211115165030.7422-8-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini --=-OEs2MkgXR/tbJE3pz7Kj Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCECow ggUcMIIEBKADAgECAhEA4rtJSHkq7AnpxKUY8ZlYZjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl bnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTkwMTAyMDAwMDAwWhcNMjIwMTAxMjM1 OTU5WjAkMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZyYWRlYWQub3JnMIIBIjANBgkqhkiG9w0B AQEFAAOCAQ8AMIIBCgKCAQEAsv3wObLTCbUA7GJqKj9vHGf+Fa+tpkO+ZRVve9EpNsMsfXhvFpb8 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