e5cb62e7b6
Consider the following nested setup: An L1 host uses some virtio device (e.g. virtio-keyboard) for the L2 guest, and this L2 guest passes this device through to the L3 guest. Since the L3 guest sees a virtio device, it might send virtio notifications to the QEMU in L2 for that device. But since the QEMU in L2 defined this device as vfio-ccw, the function handle_virtio_ccw_notify() cannot handle this and crashes: It calls virtio_ccw_get_vdev() that casts sch->driver_data into a VirtioCcwDevice, but since "sch" belongs to a vfio-ccw device, that driver_data rather points to a CcwDevice instead. So as soon as QEMU tries to use some VirtioCcwDevice specific data from that device, we've lost. We must not take virtio notifications for such devices. Thus fix the issue by adding a check to the handle_virtio_ccw_notify() handler to refuse all devices that are not our own virtio devices. Like in the other branches that detect wrong settings, we return -EINVAL from the function, which will later be placed in GPR2 to inform the guest about the error. Reviewed-by: Halil Pasic <pasic@linux.ibm.com> Reviewed-by: Eric Farman <farman@linux.ibm.com> Tested-by: Eric Farman <farman@linux.ibm.com> Reviewed-by: Cornelia Huck <cohuck@redhat.com> Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com> Signed-off-by: Thomas Huth <thuth@redhat.com> Message-ID: <20251118174047.73103-1-thuth@redhat.com>
99 lines
2.9 KiB
C
99 lines
2.9 KiB
C
/*
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* Support for QEMU/KVM hypercalls on s390
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*
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* Copyright 2012 IBM Corp.
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* Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or (at
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* your option) any later version. See the COPYING file in the top-level
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* directory.
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*/
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#include "qemu/osdep.h"
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#include "qemu/error-report.h"
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#include "cpu.h"
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#include "hw/s390x/s390-virtio-ccw.h"
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#include "hw/s390x/s390-hypercall.h"
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#include "hw/s390x/ioinst.h"
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#include "hw/s390x/css.h"
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#include "virtio-ccw.h"
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static int handle_virtio_notify(uint64_t mem)
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{
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MachineState *ms = MACHINE(qdev_get_machine());
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if (mem < ms->ram_size) {
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/* Early printk */
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return 0;
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}
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return -EINVAL;
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}
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static int handle_virtio_ccw_notify(uint64_t subch_id, uint64_t data)
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{
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SubchDev *sch;
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VirtIODevice *vdev;
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int cssid, ssid, schid, m;
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uint16_t vq_idx = data;
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if (ioinst_disassemble_sch_ident(subch_id, &m, &cssid, &ssid, &schid)) {
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return -EINVAL;
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}
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sch = css_find_subch(m, cssid, ssid, schid);
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if (!sch || !css_subch_visible(sch)) {
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return -EINVAL;
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}
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if (sch->id.cu_type != VIRTIO_CCW_CU_TYPE) {
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/*
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* This might happen in nested setups: If the L1 host defined the
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* L2 guest with a virtio device (e.g. virtio-keyboard), and the
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* L2 guest passes this device through to the L3 guest, the L3 guest
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* might send virtio notifications to the QEMU in L2 for that device.
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* But since the QEMU in L2 defined this device as vfio-ccw, it's not
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* a VirtIODevice that we can handle here!
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*/
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warn_report_once("Got virtio notification for unsupported device "
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"on subchannel %02x.%1x.%04x!", cssid, ssid, schid);
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return -EINVAL;
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}
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vdev = virtio_ccw_get_vdev(sch);
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if (vq_idx >= VIRTIO_QUEUE_MAX || !virtio_queue_get_num(vdev, vq_idx)) {
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return -EINVAL;
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}
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if (virtio_vdev_has_feature(vdev, VIRTIO_F_NOTIFICATION_DATA)) {
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virtio_queue_set_shadow_avail_idx(virtio_get_queue(vdev, vq_idx),
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(data >> 16) & 0xFFFF);
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}
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virtio_queue_notify(vdev, vq_idx);
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return 0;
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}
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static uint64_t handle_storage_limit(void)
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{
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S390CcwMachineState *s390ms = S390_CCW_MACHINE(qdev_get_machine());
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return s390_get_memory_limit(s390ms) - 1;
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}
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void handle_diag_500(S390CPU *cpu, uintptr_t ra)
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{
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CPUS390XState *env = &cpu->env;
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const uint64_t subcode = env->regs[1];
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switch (subcode) {
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case DIAG500_VIRTIO_NOTIFY:
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env->regs[2] = handle_virtio_notify(env->regs[2]);
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break;
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case DIAG500_VIRTIO_CCW_NOTIFY:
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env->regs[2] = handle_virtio_ccw_notify(env->regs[2], env->regs[3]);
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break;
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case DIAG500_STORAGE_LIMIT:
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env->regs[2] = handle_storage_limit();
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break;
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default:
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s390_program_interrupt(env, PGM_SPECIFICATION, ra);
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}
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}
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