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=unavailable 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 B6FB6C433E2 for ; Tue, 8 Sep 2020 18:05:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 54D512074D for ; Tue, 8 Sep 2020 18:05:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599588309; bh=K98OJv2GkRlivNz34fJtumK8rOF+TnINn+n3z1nP8KI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=i9ZUGD02ULTGOag3uv0Ez8cCUJdsnbpi+ay3lzhtBGqBXW1RDLj0o/jkPTBoKUb7V QaGQxLKu/m0EgxyZRTRqz77sL5MKDSsaLw1LoSet4TPLofZuqTWpe3weYQuIkrvK5o GkHaMw+aGsnCsSHW04F5NtbhRlJfCu45QGB57ZDI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732195AbgIHSFH (ORCPT ); Tue, 8 Sep 2020 14:05:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:56086 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731520AbgIHQMK (ORCPT ); Tue, 8 Sep 2020 12:12:10 -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 39F9724762; Tue, 8 Sep 2020 15:50:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599580258; bh=K98OJv2GkRlivNz34fJtumK8rOF+TnINn+n3z1nP8KI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ycZEGvGvJXATZMaOroP/DtFEsSYuSrGh1qYNvarU7GPytliRm+ZgBmq2aVQwh4AYF KyekqE9pSwEP9akgu0pMWC4SHpd/NTAzIfHPvnpb9BHtxaUPxHfLv3FZapA3FkGZY2 5CKOnJXb0BxvmiG6s8/8+lNjS44I4oNsIUJUsvik= 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 4.19 81/88] KVM: arm64: Defer guest entry when an asynchronous exception is pending Date: Tue, 8 Sep 2020 17:26:22 +0200 Message-Id: <20200908152225.234291269@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200908152221.082184905@linuxfoundation.org> References: <20200908152221.082184905@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. Cc: stable@vger.kernel.org # v4.19 Signed-off-by: James Morse Signed-off-by: Marc Zyngier Signed-off-by: Andre Przywara Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kvm/hyp/entry.S | 15 +++++++++++++++ 1 file changed, 15 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 +63,20 @@ 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 // Restore guest regs x0-x17