From patchwork Thu Oct 10 18:23:36 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 1995775 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; dkim=pass (2048-bit key; secure) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=NvLTRej/; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20230601 header.b=wwsVmKdK; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.infradead.org (client-ip=2607:7c80:54:3::133; helo=bombadil.infradead.org; envelope-from=kvm-riscv-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org; receiver=patchwork.ozlabs.org) Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (secp384r1) server-digest SHA384) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4XPjHV24vLz1xsc for ; Fri, 11 Oct 2024 08:16:38 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:Reply-To:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:Message-ID :References:Mime-Version:In-Reply-To:Date:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=KU7dlcIhPbvL2g07Yt7o6Z1j0QYJXNJA5ILY4esmpfU=; b=NvLTRej/j6C0c8 Fk5su6190uq4N9TE61oheRcdXfk3yteXDzMP9JK8bOFECo9W8f2+FjTJWBa93XkAynMssGcCInnsy YL7iFTOuCBDo9+I3uvAdJ5sO4UX2KhTq3Mu/peMy+nwsTe1KIdLMgsPJmsoEEP2AMEiS4x5Tbm4aa +i0UbYGc0bpf3P4gS6tHAYDQhvhCx8VBv+uU5Z82UlmEiD91QWrs8Zoot8CYody/qVrCiBpAT28Zg rFWVRh+ZueXwpdCcHgrbTVN4r+xMgkY1ho40qWv9EMDFTVqYGS+djkhEde/tUFlcmQ1UmffE6ENyH CYMqo25DrDbOkIMCiMTA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1sz0WR-0000000ENdd-3UZm; Thu, 10 Oct 2024 21:16:35 +0000 Received: from mail-pf1-x44a.google.com ([2607:f8b0:4864:20::44a]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1syxrQ-0000000DqX2-1vaC for kvm-riscv@lists.infradead.org; Thu, 10 Oct 2024 18:26:06 +0000 Received: by mail-pf1-x44a.google.com with SMTP id d2e1a72fcca58-71dfda86c8dso1460314b3a.0 for ; Thu, 10 Oct 2024 11:26:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1728584763; x=1729189563; darn=lists.infradead.org; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:reply-to:from:to:cc:subject:date :message-id:reply-to; bh=w3u38MFKj4Hgu0NiviVwRjtFpk/ioMNBGBDQlt4DAgY=; b=wwsVmKdK+SipFg1qIF50TrdP6Oo7jO28ReLYz/VDjQtbPUYfeyWnk0GVNrM0uvKMns yzO1p2PHSyt6/6J6LjJccz4eC9X33n2N2DFqSywzlwGAsAWPs0+b7iefqw5tZpUARPQu 9OG64S1K6L+hc8UcCB61w0V2JL630JzshC0mLEAVFvK8USjgHGCuqzpy7gkmEW0tty66 NRob1YtQ6GGUHdVw6r2QY0qsQ4+DlBD5nwBCrRtcLzLwX9krXorOWvD+nF58Mr7YwjaH LDcNdo4BOKyAvdYIXqY2QFZaKTbi1CdYfH/QTc06gv+b8kc00QbcJRcZEUai+QUcejZU 3v4Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728584763; x=1729189563; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:reply-to:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=w3u38MFKj4Hgu0NiviVwRjtFpk/ioMNBGBDQlt4DAgY=; b=SeBjboETaRcEIPH03OHsDkPT4pzSctBsXH2iw1CUzSr/Sk22yrc8YPYCG7SnHwFIxZ 5BwDWGdPigEIPZwMc8k35gUYtRhuHflApD3KM8HCxz74jz1qt6+XH8PCEO8cxXb27K9h m+xM0034v+7sJI1LzawKRCXbEBZ2/0NYw+fv9TcNetlBM+r2rp9t4mB5a62TesunTD/+ LPyep4AmCaRaRSTREF0r8cjTSnwNqTh6G6BGumv2ELWUZxXQ04XW2JXZLyavz3ayiZfJ DYVAym+inX14UZRAAx8VNpSwu4zz+XaSCzug7PxwevwAMnGcXd8G2fD5kFnDv2hykkH/ cpzw== X-Forwarded-Encrypted: i=1; AJvYcCV2rjsZdy136I04DGhe+nQ4Y+gZDoJsRlTXgIo4SpksqIcSi+9LeSBp1Xm9WSIoJNpwOzgfRqrex04=@lists.infradead.org X-Gm-Message-State: AOJu0YyrYdOI23dWBzAmVFGrAOmaPRRshRm5/f+SXwEMkOvVKk7wag2O AXmCHFXco5aUhfGHMdmIDq88jSAccLrjVyjIG45BzYKtOpUTPWGnNOIiNVjda+9praRWf10fvDy tqg== X-Google-Smtp-Source: AGHT+IHthU1bxxWE76UmRU/cmSB/2b+tJYVulTyd1SGmZGLYBHQFEbukUNmDJAlwNs2CFth+SfvGFADhDCI= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:9d:3983:ac13:c240]) (user=seanjc job=sendgmr) by 2002:a05:6a00:2f51:b0:71e:dd:8f9b with SMTP id d2e1a72fcca58-71e1dbe8750mr6976b3a.5.1728584762866; Thu, 10 Oct 2024 11:26:02 -0700 (PDT) Date: Thu, 10 Oct 2024 11:23:36 -0700 In-Reply-To: <20241010182427.1434605-1-seanjc@google.com> Mime-Version: 1.0 References: <20241010182427.1434605-1-seanjc@google.com> X-Mailer: git-send-email 2.47.0.rc1.288.g06298d1525-goog Message-ID: <20241010182427.1434605-35-seanjc@google.com> Subject: [PATCH v13 34/85] KVM: Get writable mapping for __kvm_vcpu_map() only when necessary From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Sean Christopherson Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, " =?utf-8?q?Alex_Benn=C3=A9e?= " , Yan Zhao , David Matlack , David Stevens , Andrew Jones X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241010_112604_609917_2A897CB9 X-CRM114-Status: GOOD ( 10.35 ) X-Spam-Score: -9.5 (---------) X-Spam-Report: Spam detection software, running on the system "bombadil.infradead.org", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: When creating a memory map for read, don't request a writable pfn from the primary MMU. While creating read-only mappings can be theoretically slower, as they don't play nice with fast GUP due to the [...] Content analysis details: (-9.5 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:44a listed in] [list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record -7.5 USER_IN_DEF_DKIM_WL From: address is in the default DKIM welcome-list -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] -0.0 DKIMWL_WL_MED DKIMwl.org - Medium trust sender X-BeenThere: kvm-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Sender: "kvm-riscv" Errors-To: kvm-riscv-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org When creating a memory map for read, don't request a writable pfn from the primary MMU. While creating read-only mappings can be theoretically slower, as they don't play nice with fast GUP due to the need to break CoW before mapping the underlying PFN, practically speaking, creating a mapping isn't a super hot path, and getting a writable mapping for reading is weird and confusing. Tested-by: Alex Bennée Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 080740f65061..b845e9252633 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3122,7 +3122,7 @@ int __kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map, struct kvm_follow_pfn kfp = { .slot = gfn_to_memslot(vcpu->kvm, gfn), .gfn = gfn, - .flags = FOLL_WRITE, + .flags = writable ? FOLL_WRITE : 0, .refcounted_page = &map->pinned_page, .pin = true, };