From patchwork Tue Jul 9 12:24:54 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 11036935 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 16FDF138B for ; Tue, 9 Jul 2019 12:27:08 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 03F0028628 for ; Tue, 9 Jul 2019 12:27:08 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EC4FD28707; Tue, 9 Jul 2019 12:27:07 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 7D1BE28628 for ; Tue, 9 Jul 2019 12:27:07 +0000 (UTC) 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=+xLLHtQ19bLQLJ20JaY+gIu2LubvbSEvNlyrdCPCNKw=; b=tP1X3zt8WVPvQI s03h1f7EClQvE/FvSw2/lp55YXgS/zRqm8UBXIriCa2WqDE4wMqD5XLNNkl8DanZ2BTR+hkobz4Y3 co0syos9xBuWPCKM5j26Yxgu4zCAFZO71Vpcd7EaPDbk7e1aOSSY77GrmnHIhFMBZVkFsShKyT3dC bb7AAzd1TD3SCzw0Lh0jNEHbpP0A6nDbJR2WSKjsulerZEtB/xuWjLyk0hCsy9le6bvHStftFp/qf qCZtSHUK7lI5QmDyLE15s5VVC7Hb8plwEzBjGRrMRFecS4HMoTBgWMiCfCUq6NNNCanX6mO6IQAIk +TmcqHC6XAIbUf5VApjw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hkpD2-0007pe-A5; Tue, 09 Jul 2019 12:27:00 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hkpBa-0006Wb-N9 for linux-arm-kernel@lists.infradead.org; Tue, 09 Jul 2019 12:25:32 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2E8BE1515; Tue, 9 Jul 2019 05:25:30 -0700 (PDT) Received: from filthy-habits.cambridge.arm.com (unknown [10.1.197.61]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 638713F59C; Tue, 9 Jul 2019 05:25:28 -0700 (PDT) From: Marc Zyngier To: Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= Subject: [PATCH 05/18] KVM: arm64: Defer guest entry when an asynchronous exception is pending Date: Tue, 9 Jul 2019 13:24:54 +0100 Message-Id: <20190709122507.214494-6-marc.zyngier@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190709122507.214494-1-marc.zyngier@arm.com> References: <20190709122507.214494-1-marc.zyngier@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190709_052530_914980_4FA54F09 X-CRM114-Status: UNSURE ( 9.45 ) X-CRM114-Notice: Please train this message. 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: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Julien Thierry , Andre Przywara , Suzuki K Poulose , Steven Price , Eric Auger , James Morse , Sudeep Holla , Andrew Murray , Dave Martin , 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 X-Virus-Scanned: ClamAV using ClamSMTP From: James Morse SError that occur during world-switch's entry to the guest will be accounted to the guest, as the exception is masked until we enter the guest... but we want to attribute the SError as precisely as possible. Reading DISR_EL1 before guest entry requires free registers, and using ESB+DISR_EL1 to consume and read back the ESR would leave KVM holding a host SError... We would rather leave the SError pending and let the host take it once we exit world-switch. To do this, we need to defer guest-entry if an SError is pending. Read the ISR to see if SError (or an IRQ) is pending. If so fake an exit. Place this check between __guest_enter()'s save of the host registers, and restore of the guest's. SError that occur between here and the eret into the guest must have affected the guest's registers, which we can naturally attribute to the guest. The dsb is needed to ensure any previous writes have been done before we read ISR_EL1. On systems without the v8.2 RAS extensions this doesn't give us anything as we can't contain errors, and the ESR bits to describe the severity are all implementation-defined. Replace this with a nop for these systems. Signed-off-by: James Morse Signed-off-by: Marc Zyngier --- arch/arm64/kvm/hyp/entry.S | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index fb2e218ce0c7..ebc8eb247bc9 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -6,6 +6,7 @@ #include +#include #include #include #include @@ -52,6 +53,20 @@ ENTRY(__guest_enter) // Store the host regs save_callee_saved_regs x1 + // Now the host state is stored if we have a pending RAS SError it must + // affect the host. If any asynchronous exception is pending we defer + // the guest entry. The DSB isn't necessary before v8.2 as any SError + // would be fatal. +alternative_if ARM64_HAS_RAS_EXTN + dsb nshst + isb +alternative_else_nop_endif + mrs x1, isr_el1 + cbz x1, 1f + mov x0, #ARM_EXCEPTION_IRQ + ret + +1: add x18, x0, #VCPU_CONTEXT // Macro ptrauth_switch_to_guest format: