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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12D57ECAAD4 for ; Sat, 3 Sep 2022 20:06:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233408AbiICUGJ (ORCPT ); Sat, 3 Sep 2022 16:06:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229509AbiICUGG (ORCPT ); Sat, 3 Sep 2022 16:06:06 -0400 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 78B544DB0E; Sat, 3 Sep 2022 13:06:03 -0700 (PDT) Received: from pps.filterd (m0246630.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 2839EGQB031956; Sat, 3 Sep 2022 20:06:00 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=corp-2022-7-12; bh=DvtTk1Z/ESP+39Y8V1aV0Jj1x/WVB/9tkpYI5Y8WQPA=; b=pZSp6QJ8sJxouzIrBcgGoyhKRUsxh8Gkz7M7iedc3WmPmrNOCoqAmjYpmMTO5/BrfZoO PGidL0AumTumJJ0Tk76fzFgb54+36dVNWz69ron937qSX5ebQJ+dj1DhF8nrHiZsaAki ziA3/31ioQ4eL81sd9xsYjERqJIWGh298CUw75yMzlUiV97gl9VjrFCkuLXcJ4v8ni1Z NotYlHWgDKR9lY7RnBby7o2tExfy/shPuoud6ReqiPTbvRgHF1HxIzaBr/zGgX67DQ2H 7pl6jodzdgqNh4g+Ybl854KZG67lsCpiFqhTZZa9EUugeGUli0evBXoRoqBH4Ouc/Hb/ Ew== Received: from phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta01.appoci.oracle.com [138.1.114.2]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 3jbwbc101k-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 03 Sep 2022 20:05:59 +0000 Received: from pps.filterd (phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (8.17.1.5/8.17.1.5) with ESMTP id 283IkqjE016402; Sat, 3 Sep 2022 20:05:58 GMT Received: from pps.reinject (localhost [127.0.0.1]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 3jbwc0ma52-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 03 Sep 2022 20:05:58 +0000 Received: from phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 283K5wZM018676; Sat, 3 Sep 2022 20:05:58 GMT Received: from alaljime-amd-bm-e3.allregionalphxs.osdevelopmenphx.oraclevcn.com (alaljime-amd-bm-e3.allregionalphxs.osdevelopmenphx.oraclevcn.com [100.107.196.22]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTP id 3jbwc0ma4y-1; Sat, 03 Sep 2022 20:05:58 +0000 From: Alejandro Jimenez To: seanjc@google.com, pbonzini@redhat.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, suravee.suthikulpanit@amd.com, mlevitsk@redhat.com, joao.m.martins@oracle.com, alejandro.j.jimenez@oracle.com Subject: [PATCH 1/1] KVM: x86: Allow emulation of EOI writes with AVIC enabled Date: Sat, 3 Sep 2022 20:05:57 +0000 Message-Id: <20220903200557.1719-1-alejandro.j.jimenez@oracle.com> X-Mailer: git-send-email 2.34.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-09-03_10,2022-08-31_03,2022-06-22_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 malwarescore=0 mlxscore=0 suspectscore=0 mlxlogscore=999 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2207270000 definitions=main-2209030104 X-Proofpoint-ORIG-GUID: oQMLQonpWEv3fjYMeJ-EE-4jul812gHa X-Proofpoint-GUID: oQMLQonpWEv3fjYMeJ-EE-4jul812gHa Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org According to section 15.29.9.2 - AVIC Access to un-accelerated vAPIC register of the AMD APM [1]: "A guest access to an APIC register that is not accelerated by AVIC results in a #VMEXIT with the exit code of AVIC_NOACCEL. This fault is also generated if an EOI is attempted when the highest priority in-service interrupt is set for level-triggered mode." This is also stated in Table 15-22 - Guest vAPIC Register Access Behavior, confirming that AVIC hardware traps on EOI writes for level triggered interrupts, and leading to the following call stack: avic_unaccelerated_access_interception() -> avic_unaccel_trap_write() -> kvm_apic_write_nodecode() -> kvm_lapic_msr_read() -> kvm_lapic_reg_read() In kvm_lapic_reg_read(), the APIC_EOI offset (0xb0) is not allowed as valid, so the error returned triggers the assertion introduced by 'commit 70c8327c11c6 ("KVM: x86: Bug the VM if an accelerated x2APIC trap occurs on a "bad" reg")' and kills the VM. Add APIC_EOI offset to the valid mask in kvm_lapic_reg_read() to allow the emulation of EOI behavior for level triggered interrupts. [1] https://www.amd.com/system/files/TechDocs/24593.pdf Fixes: 0105d1a52640 ("KVM: x2apic interface to lapic") Signed-off-by: Alejandro Jimenez Cc: stable@vger.kernel.org --- I am unsure as to the proper commit to use for the Fixes: tag. Technically the issue was introduced by the initial SVM AVIC commits in 2016, since they failed to add the EOI offset to the valid mask. To be safe, I used the commit that introduces the valid mask, but that is somewhat misleading since at the time AVIC was not available, and I believe that Intel posted interrupts implementation does not require access to EOI offset in this code. Please correct Fixes: tag if necessary. --- arch/x86/kvm/lapic.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 9dda989a1cf0..61041fecfa89 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1452,6 +1452,7 @@ static int kvm_lapic_reg_read(struct kvm_lapic *apic, u32 offset, int len, APIC_REG_MASK(APIC_LVR) | APIC_REG_MASK(APIC_TASKPRI) | APIC_REG_MASK(APIC_PROCPRI) | + APIC_REG_MASK(APIC_EOI) | APIC_REG_MASK(APIC_LDR) | APIC_REG_MASK(APIC_DFR) | APIC_REG_MASK(APIC_SPIV) | -- 2.34.2