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=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 8C609C433E2 for ; Fri, 11 Sep 2020 13:43:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DE7F22272 for ; Fri, 11 Sep 2020 13:43:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599831832; bh=WrKfuh3yAbeARMYEHR1js9UP1lzjuhWNQKJKsRGMwbg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZeemT0X7zy2hgJo/cDdn8hXDdIjJYQdPt2pjDExHGVEwzqUFyc9oe/crY4cwvQVE+ mOkuQbgM3mjj6rWK9cXKOdepDQzPi9s91H8bot5XPZaDI9RUWkdUbZ9cqHbpl7JnKH CPulCq4FkXpWRNkS/8Z3p9Y8UqPL3lhb5m0f6exI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725778AbgIKNnd (ORCPT ); Fri, 11 Sep 2020 09:43:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:52804 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726205AbgIKNFo (ORCPT ); Fri, 11 Sep 2020 09:05:44 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 094EE22244; Fri, 11 Sep 2020 12:57:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599829067; bh=WrKfuh3yAbeARMYEHR1js9UP1lzjuhWNQKJKsRGMwbg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pirSo71w2yZIoqOUcuLqses2fxB0OqL2CPPn3InnLvm4kIUyeXsMfep0qDYEUpr/v CoffsopHQvCyqLtOzq5L6PqjCmX2tv8jzLHGqQLr+i/q8ScJ8JmoqqO7qAvTxzQLiR 6NRHosyI5FMsoaD3FgqaDjH9K2RsOVQmK/NUooQM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , James Morse , Marc Zyngier , Andre Przywara Subject: [PATCH 4.9 53/71] KVM: arm64: Defer guest entry when an asynchronous exception is pending Date: Fri, 11 Sep 2020 14:46:37 +0200 Message-Id: <20200911122507.555558810@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200911122504.928931589@linuxfoundation.org> References: <20200911122504.928931589@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: James Morse commit 5dcd0fdbb492d49dac6bf21c436dfcb5ded0a895 upstream. 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. v4.9-backport: as this kernel version doesn't have the RAS support at all, remove the RAS alternative. Cc: stable@vger.kernel.org # v4.9 Signed-off-by: James Morse Signed-off-by: Marc Zyngier [ James: Removed v8.2 RAS related barriers ] Signed-off-by: James Morse Signed-off-by: Andre Przywara Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kvm/hyp/entry.S | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -17,6 +17,7 @@ #include +#include #include #include #include @@ -62,6 +63,15 @@ 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. + mrs x1, isr_el1 + cbz x1, 1f + mov x0, #ARM_EXCEPTION_IRQ + ret + +1: add x18, x0, #VCPU_CONTEXT // Restore guest regs x0-x17