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 C0BF2EDE99E for ; Thu, 14 Sep 2023 09:15:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233767AbjINJPi (ORCPT ); Thu, 14 Sep 2023 05:15:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52134 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230515AbjINJPg (ORCPT ); Thu, 14 Sep 2023 05:15:36 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B443BCEB; Thu, 14 Sep 2023 02:15:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=JsJPsTpwWFpzVVZeNPo1BZax52gHDIRYYUVVchDwJ3M=; b=B4YEAoOanRjVv2OjcjGuDw4eGa 20n1qriaULmEv8IhqbKsn+Q0UIvBsVJgR161kcKQLo3PYwIOMKrVaTlowg/jYeMU7LIfkWGZOaxCV hkoFj9doGI4jSdw4GvZ5o3dc739gyfsuhyiPDiMCugcMeeG9kRDHckRVo6qfGddQ6HlZdPkTG0d01 0X2rZHN32WLIJ1NKltrYFE+sEsCjeQqb82QpizVC/01MPjmKmhg4Qu1os62GsvTi1lIEldMshzHGp 2sLpLNLmj8xKhvgXDAyh9hEsV+oXoy/iii26ZkxLrcGK9xmKlrvFilqeeP0gqvnrL8bPB+fuzR1hy vfPUWjtA==; Received: from [54.239.6.190] (helo=u3832b3a9db3152.ant.amazon.com) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1qgiRe-00235x-Ck; Thu, 14 Sep 2023 09:15:30 +0000 Message-ID: Subject: Re: [PATCH 0/8] KVM: xen: update shared_info and vcpu_info handling From: David Woodhouse To: Paul Durrant , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Paul Durrant , "H. Peter Anvin" , Borislav Petkov , Dave Hansen , Ingo Molnar , Paolo Bonzini , Sean Christopherson , Thomas Gleixner , x86@kernel.org Date: Thu, 14 Sep 2023 11:15:28 +0200 In-Reply-To: <20230914084946.200043-1-paul@xen.org> References: <20230914084946.200043-1-paul@xen.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-YJFPGXPOJUd2T57PB0mD" User-Agent: Evolution 3.44.4-0ubuntu2 MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-YJFPGXPOJUd2T57PB0mD Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2023-09-14 at 08:49 +0000, Paul Durrant wrote: > From: Paul Durrant >=20 > Currently we treat the shared_info page as guest memory and the VMM infor= ms > KVM of its location using a GFN. However it is not guest memory as such; > it's an overlay page. So we pointlessly invalidate and re-cache a mapping > to the *same page* of memory every time the guest requests that shared_in= fo > be mapped into its address space. Let's avoid doing that by modifying the > pfncache code to allow activation using a fixed userspace HVA as well as > a GPA. Looks sane to me in general; thanks. The changes to the pfncache ended up being a little bit more than I originally anticipated when I said you just needed to disable the GPA=E2=86=92uHVA lookup via memslots which was about 10 lines... but I thin= k it's still true that it's worth using the pfncache to avoid reproducing the intricate mmu_notifier invalidations. --=-YJFPGXPOJUd2T57PB0mD Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCEkQw ggYQMIID+KADAgECAhBNlCwQ1DvglAnFgS06KwZPMA0GCSqGSIb3DQEBDAUAMIGIMQswCQYDVQQG EwJVUzETMBEGA1UECBMKTmV3IEplcnNleTEUMBIGA1UEBxMLSmVyc2V5IENpdHkxHjAcBgNVBAoT FVRoZSBVU0VSVFJVU1QgTmV0d29yazEuMCwGA1UEAxMlVVNFUlRydXN0IFJTQSBDZXJ0aWZpY2F0 aW9uIEF1dGhvcml0eTAeFw0xODExMDIwMDAwMDBaFw0zMDEyMzEyMzU5NTlaMIGWMQswCQYDVQQG EwJHQjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxmb3JkMRgwFgYD 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