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Tsirkin" , Mohamed Mediouni Subject: [PATCH] hw/intc: apic: stop register accesses for invalid situations Date: Sat, 11 Apr 2026 15:18:06 +0200 Message-ID: <20260411131806.94653-1-mohamed@unpredictable.fr> X-Mailer: git-send-email 2.50.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDExMDExMyBTYWx0ZWRfX6KuJnfN+jstx 6j+i1jvrST3m/ebDjNlLd3H5cNhqGcT4WVN8/SPkO4uwquQi6zi4ALnQZckV2g6p7WDvWn3/GBj 3y4aGuxYsMsQ5k/6BmhNocJkianZiGqqZa1m0zhMkq/fXi/f5YW4LmMJ1MTCP00rjNL4T4IZkOu OuScpcYR17UvWoQsGPvzE/oV4ejyfrmwz6UnMj6wDoJqBMU+OM28uPxtdv9eIvwViWeTdn+ukN0 BVXj9/cE8E9jDrTiotau+zGrpMr54csY2DL/2OiCJLOZo+aV3lkmUFFivYfuYRzIPRpyLBHrL4Y qCfKX4KheKLgym4XAIsip9bgUSFmHTomMjECbWMbFwkl9Dvhuu8oO16EXqrw4o= X-Proofpoint-GUID: gokvfFS0J8BPtV1u1cNTx0UxKfmIr46a X-Proofpoint-ORIG-GUID: gokvfFS0J8BPtV1u1cNTx0UxKfmIr46a X-Authority-Info-Out: v=2.4 cv=F9lat6hN c=1 sm=1 tr=0 ts=69da4a14 cx=c_apl:c_pps:t_out a=qkKslKyYc0ctBTeLUVfTFg==:117 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=zBtDF0ibdIbUSHW8crcA:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-11_03,2026-04-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 phishscore=0 mlxscore=0 clxscore=1030 suspectscore=0 lowpriorityscore=0 malwarescore=0 bulkscore=0 mlxlogscore=821 adultscore=0 classifier=spam authscore=0 adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2604110113 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists1p.gnu.org; Received-SPF: pass client-ip=57.103.72.239; envelope-from=mohamed@unpredictable.fr; helo=outbound.ms.icloud.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @unpredictable.fr) X-ZM-MESSAGEID: 1775913551515158501 Content-Type: text/plain; charset="utf-8" kvm-unit-tests's apic.c tests for: !APICBASE_ENABLE + attempting to read xAPIC registers is not an allowed combination. And neither is x2APIC enabled + attempting to read xAPIC registers This was tested on WHPX with kernel-irqchip=3Doff with x2APIC emulation enabled (in a posted series) and TCG. Signed-off-by: Mohamed Mediouni --- hw/intc/apic.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/hw/intc/apic.c b/hw/intc/apic.c index 8766ed00b9..c09dddef39 100644 --- a/hw/intc/apic.c +++ b/hw/intc/apic.c @@ -875,6 +875,15 @@ static uint64_t apic_mem_read(void *opaque, hwaddr add= r, unsigned size) return -1; } =20 + /* if the xAPIC is disabled, return early. */ + if (!(s->apicbase & MSR_IA32_APICBASE_ENABLE)) { + return 0xffffffff; + } + + if (s->apicbase & MSR_IA32_APICBASE_EXTD) { + return 0xffffffff; + } + index =3D (addr >> 4) & 0xff; apic_register_read(s, index, &val); =20 --=20 2.50.1 (Apple Git-155)