From patchwork Fri May 29 16:01:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 11579245 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 79C36139A for ; Fri, 29 May 2020 16:04:41 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4559B207BC for ; Fri, 29 May 2020 16:04:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="L8vR+3+A"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="nU0ZVT5b" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4559B207BC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ZWPhNiwJdxrHtQLN7OzKL9vleyOwKHkdsN6OOrTAKzE=; b=L8vR+3+A8z66aR Fy12GTMlovVu5TD5vNYGiSG/Z+ofJXJ/xBMgMwQVjoV1J1XtXhKlQNXpBU8HI99L8eUPJL6W/x/CB //apGuSaXEpTXG7+dScB8YZ0ghtwwHWOyOK5jW2S2/nMvGfERizGuNf9fWZWRJuKt/vBUP18AewYh rFeLm18+aowgL5KFQ1HIAz/GEzp2BBuU1hR+YXcTlQ1g5xcmeRwxdjkgSQWypEQfrvdT8Zse1fGsK XCvJWMjvRJWM/ghjFgNqQ8u1G1LsbdTfCjji0Coq2DERDYxYWQBFk5tjDShvuL2RUnbf5M7Wj6aLZ o+pYzFbDd/UdV0I/Sj6w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jehUr-0005bU-Ec; Fri, 29 May 2020 16:04:37 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jehSA-0003c0-O4 for linux-arm-kernel@lists.infradead.org; Fri, 29 May 2020 16:01:52 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E38A1207F9; Fri, 29 May 2020 16:01:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590768110; bh=KUg14+CaJZ9AWk7EfYjAKCvGH6MwQ8/GM6yO+OJnz2o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nU0ZVT5bQTXNPcH/tNLx+E/sIBFGAHakUFGO27I9qF638KtmUb+kEQHH5rZJGDbnL ZB2959WiGax5gp4wQEnlrIC4oUjBwVCZPpw7FgrDBuZdb3Yn+mtk114WBD9S5TxuiG cRv+1Gyb4qs2RHxmFGuSjy5Ml5m5c6+0z4RdTxAo= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jehS8-00GJKc-CJ; Fri, 29 May 2020 17:01:48 +0100 From: Marc Zyngier To: Paolo Bonzini Subject: [PATCH 09/24] KVM: arm64: Sidestep stage2_unmap_vm() on vcpu reset when S2FWB is supported Date: Fri, 29 May 2020 17:01:06 +0100 Message-Id: <20200529160121.899083-10-maz@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200529160121.899083-1-maz@kernel.org> References: <20200529160121.899083-1-maz@kernel.org> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: pbonzini@redhat.com, alexandru.elisei@arm.com, ascull@google.com, ardb@kernel.org, christoffer.dall@arm.com, dbrazdil@google.com, tabba@google.com, james.morse@arm.com, giangyi@amazon.com, zhukeqian1@huawei.com, mark.rutland@arm.com, suzuki.poulose@arm.com, will@kernel.org, yuzenghui@huawei.com, julien.thierry.kdev@gmail.com, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200529_090150_867965_91336399 X-CRM114-Status: GOOD ( 13.40 ) X-Spam-Score: -5.2 (-----) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-5.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [198.145.29.99 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 -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain 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 -0.0 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Will Deacon , Suzuki K Poulose , Keqian Zhu , Christoffer Dall , Jiang Yi , James Morse , Andrew Scull , Zenghui Yu , Julien Thierry , David Brazdil , Alexandru Elisei , Ard Biesheuvel , Fuad Tabba , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org From: Zenghui Yu stage2_unmap_vm() was introduced to unmap user RAM region in the stage2 page table to make the caches coherent. E.g., a guest reboot with stage1 MMU disabled will access memory using non-cacheable attributes. If the RAM and caches are not coherent at this stage, some evicted dirty cache line may go and corrupt guest data in RAM. Since ARMv8.4, S2FWB feature is mandatory and KVM will take advantage of it to configure the stage2 page table and the attributes of memory access. So we ensure that guests always access memory using cacheable attributes and thus, the caches always be coherent. So on CPUs that support S2FWB, we can safely reset the vcpu without a heavy stage2 unmapping. Signed-off-by: Zenghui Yu Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20200415072835.1164-1-yuzenghui@huawei.com --- arch/arm64/kvm/arm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index ee1b5bba1d08..0ea9a0266d9a 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -983,8 +983,11 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu, /* * Ensure a rebooted VM will fault in RAM pages and detect if the * guest MMU is turned off and flush the caches as needed. + * + * S2FWB enforces all memory accesses to RAM being cacheable, we + * ensure that the cache is always coherent. */ - if (vcpu->arch.has_run_once) + if (vcpu->arch.has_run_once && !cpus_have_const_cap(ARM64_HAS_STAGE2_FWB)) stage2_unmap_vm(vcpu->kvm); vcpu_reset_hcr(vcpu);