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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42031C73C41 for ; Tue, 9 Jul 2019 12:25:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 21F5C214AF for ; Tue, 9 Jul 2019 12:25:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726701AbfGIMZb (ORCPT ); Tue, 9 Jul 2019 08:25:31 -0400 Received: from foss.arm.com ([217.140.110.172]:42696 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726692AbfGIMZa (ORCPT ); Tue, 9 Jul 2019 08:25:30 -0400 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?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Cc: Andre Przywara , Andrew Murray , Dave Martin , Eric Auger , James Morse , Julien Thierry , Steven Price , Sudeep Holla , Suzuki K Poulose , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org 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 Content-Transfer-Encoding: 8bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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: -- 2.20.1