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Mon, 17 Jun 2019 17:57:32 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3030.oracle.com with ESMTP id 2t59gdc0hq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 17 Jun 2019 17:57:32 +0000 Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x5HHvUZF029068; Mon, 17 Jun 2019 17:57:30 GMT Received: from spark.ravello.local (/213.57.127.2) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 17 Jun 2019 10:57:29 -0700 From: Liran Alon To: qemu-devel@nongnu.org Date: Mon, 17 Jun 2019 20:56:52 +0300 Message-Id: <20190617175658.135869-4-liran.alon@oracle.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190617175658.135869-1-liran.alon@oracle.com> References: <20190617175658.135869-1-liran.alon@oracle.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9291 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906170160 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9291 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906170160 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] X-Received-From: 156.151.31.85 Subject: [Qemu-devel] [QEMU PATCH v3 3/9] KVM: i386: Re-inject #DB to guest with updated DR6 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: ehabkost@redhat.com, kvm@vger.kernel.org, maran.wilson@oracle.com, mtosatti@redhat.com, dgilbert@redhat.com, Liran Alon , Nikita Leshenko , Krish Sadhukhan , pbonzini@redhat.com, rth@twiddle.net, jmattson@google.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" If userspace (QEMU) debug guest, when #DB is raised in guest and intercepted by KVM, KVM forwards information on #DB to userspace instead of injecting #DB to guest. While doing so, KVM don't update vCPU DR6 but instead report the #DB DR6 value to userspace for further handling. See KVM's handle_exception() DB_VECTOR handler. QEMU handler for this case is kvm_handle_debug(). This handler basically checks if #DB is related to one of user set hardware breakpoints and if not, it re-inject #DB into guest. The re-injection is done by setting env->exception_injected to #DB which will later be passed as events.exception.nr to KVM_SET_VCPU_EVENTS ioctl by kvm_put_vcpu_events(). However, in case userspace re-injects #DB, KVM expects userspace to set vCPU DR6 as reported to userspace when #DB was intercepted! Otherwise, KVM_REQ_EVENT handler will inject #DB with wrong DR6 to guest. Fix this issue by updating vCPU DR6 appropriately when re-inject #DB to guest. Reviewed-by: Nikita Leshenko Reviewed-by: Krish Sadhukhan Signed-off-by: Liran Alon --- target/i386/kvm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/target/i386/kvm.c b/target/i386/kvm.c index 738dd91ff3cc..c8fd53055d37 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -3558,6 +3558,9 @@ static int kvm_handle_debug(X86CPU *cpu, /* pass to guest */ env->exception_injected = arch_info->exception; env->has_error_code = 0; + if (arch_info->exception == EXCP01_DB) { + env->dr[6] = arch_info->dr6; + } } return ret; -- 2.20.1