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 0869AC433F5 for ; Sat, 20 Nov 2021 17:02:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232060AbhKTRF2 (ORCPT ); Sat, 20 Nov 2021 12:05:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229949AbhKTRF1 (ORCPT ); Sat, 20 Nov 2021 12:05:27 -0500 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3096FC061574; Sat, 20 Nov 2021 09:02:24 -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=1djqxICSM9IYACohxCK/TatYXA+vpDHPuX47RR/2pVo=; b=eRJpUrg7QqrPDst2i5G+Wq/wlz oDnChP+5KKyQM5dvW4Psx2kpJ+IIHBXD22EJH7/FdV1g+birlaTtwSPRTSAoln6pYUSEStJH76Z5L CNfuJH70eBaAElTFKmK78NUx6OFzTigk5WNsIlrCCsEe7F4Ueb/QJ+IYTMUHSLRXswY30kqbqHUFp e87JUEut76RykPQ3aa+2l54wTQdHrfpEvwMItb1KtPbEH4vEhw4fFMj5QWPLYYJOWrbZyhNWr/ugd l4VJgcVU05qPR4MXdu1f35AExZ+CnP5WYa1vq3MTCnct9LmZFT65cEtsausZl1XkYkCzqsWxr+gdK VsTsJDeQ==; 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 1moTkf-00CkGg-Gi; Sat, 20 Nov 2021 17:02:09 +0000 Message-ID: Subject: Re: [PATCH v4 11/11] KVM: x86: First attempt at converting nested virtual APIC page to gpc From: David Woodhouse To: Mika =?ISO-8859-1?Q?Penttil=E4?= , 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, Marc Zyngier , James Morse , Alexandru Elisei , Suzuki K Poulose , Catalin Marinas , Will Deacon , Huacai Chen , Aleksandar Markovic , Michael Ellerman , Benjamin Herrenschmidt , Anup Patel , Christian Borntraeger , kvmarm@lists.cs.columbia.edu, linux-arm-kernel , linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-s390@vger.kernel.org Date: Sat, 20 Nov 2021 17:02:03 +0000 In-Reply-To: References: <20211120102810.8858-1-dwmw2@infradead.org> <20211120102810.8858-12-dwmw2@infradead.org> <8f434989aebd257a36cafcb414edcc5906c02728.camel@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-4SL7/aYUfCZQHkl1DXdk" 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 --=-4SL7/aYUfCZQHkl1DXdk Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sat, 2021-11-20 at 18:30 +0200, Mika Penttil=C3=A4 wrote: >=20 > On 20.11.2021 18.21, David Woodhouse wrote: > > On Sat, 2021-11-20 at 17:48 +0200, Mika Penttil=C3=A4 wrote: > > > > @@ -9785,6 +9787,14 @@ static int vcpu_enter_guest(struct kvm_vcpu = *vcpu) > > > > local_irq_disable(); > > > > vcpu->mode =3D IN_GUEST_MODE; > > > > =20 > > > > + /* > > > > + * If the guest requires direct access to mapped L1 pages, ch= eck > > > > + * the caches are valid. Will raise KVM_REQ_GET_NESTED_STATE_= PAGES > > > > + * to go and revalidate them, if necessary. > > > > + */ > > > > + if (is_guest_mode(vcpu) && kvm_x86_ops.nested_ops->check_gues= t_maps) > > > > + kvm_x86_ops.nested_ops->check_guest_maps(vcpu); > > > > > > But KVM_REQ_GET_NESTED_STATE_PAGES is not check until next > > > vcpu_enter_guest() entry ? > > > > Sure, but that's why this call to ->check_guest_maps() comes just a few > > lines *before* the 'if (kvm_cpu_exit_request(vcpu))' that will bounce > > us back out so that we go through vcpu_enter_guest() from the start > > again? > > Yes, I had forgotten that...=3D Having said that, I think Paolo was rightly trying to persuade me that we don't need the check there at all anyway. Because the *invalidation* will raise KVM_REQ_GPC_INVALIDATE, and that's sufficient to bounce us out of IN_GUEST_MODE without us having to check the GPC explicitly. We do need to ensure that we are up to date with memslots changes, but that's a bit simpler, and we have kvm_arch_memslots_changed() waking us for that too. So yeah, with sufficient thought I think we can be entirely event- driven instead of having to have an explicit *check* on entry. --=-4SL7/aYUfCZQHkl1DXdk 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 RgL8vD+L133wK6csYoDU7zKiAo92FMUWaY1Hy6HqvVr9oevfTV3xhB5rQO1RHJoAfkvhy+wpjo7Q cXuzkOpibq2YurVStHAiGqAOMGMXhcVGqPuGhcVcVzVUjsvEzAV9Po9K2rpZ52FE4rDkpDK1pBK+ 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