hw/xen: Implement EVTCHNOP_unmask
This finally comes with a mechanism for actually injecting events into the guest vCPU, with all the atomic-test-and-set that's involved in setting the bit in the shinfo, then the index in the vcpu_info, and injecting either the lapic vector as MSI, or letting KVM inject the bare vector. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Paul Durrant <paul@xen.org>
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@ -224,6 +224,13 @@ int xen_evtchn_set_callback_param(uint64_t param)
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return ret;
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}
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static void inject_callback(XenEvtchnState *s, uint32_t vcpu)
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{
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int type = s->callback_param >> CALLBACK_VIA_TYPE_SHIFT;
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kvm_xen_inject_vcpu_callback_vector(vcpu, type);
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}
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static bool valid_port(evtchn_port_t port)
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{
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if (!port) {
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@ -294,6 +301,152 @@ int xen_evtchn_status_op(struct evtchn_status *status)
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return 0;
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}
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/*
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* Never thought I'd hear myself say this, but C++ templates would be
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* kind of nice here.
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*
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* template<class T> static int do_unmask_port(T *shinfo, ...);
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*/
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static int do_unmask_port_lm(XenEvtchnState *s, evtchn_port_t port,
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bool do_unmask, struct shared_info *shinfo,
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struct vcpu_info *vcpu_info)
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{
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const int bits_per_word = BITS_PER_BYTE * sizeof(shinfo->evtchn_pending[0]);
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typeof(shinfo->evtchn_pending[0]) mask;
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int idx = port / bits_per_word;
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int offset = port % bits_per_word;
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mask = 1UL << offset;
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if (idx >= bits_per_word) {
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return -EINVAL;
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}
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if (do_unmask) {
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/*
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* If this is a true unmask operation, clear the mask bit. If
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* it was already unmasked, we have nothing further to do.
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*/
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if (!((qatomic_fetch_and(&shinfo->evtchn_mask[idx], ~mask) & mask))) {
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return 0;
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}
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} else {
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/*
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* This is a pseudo-unmask for affinity changes. We don't
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* change the mask bit, and if it's *masked* we have nothing
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* else to do.
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*/
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if (qatomic_fetch_or(&shinfo->evtchn_mask[idx], 0) & mask) {
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return 0;
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}
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}
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/* If the event was not pending, we're done. */
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if (!(qatomic_fetch_or(&shinfo->evtchn_pending[idx], 0) & mask)) {
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return 0;
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}
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/* Now on to the vcpu_info evtchn_pending_sel index... */
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mask = 1UL << idx;
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/* If a port in this word was already pending for this vCPU, all done. */
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if (qatomic_fetch_or(&vcpu_info->evtchn_pending_sel, mask) & mask) {
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return 0;
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}
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/* Set evtchn_upcall_pending for this vCPU */
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if (qatomic_fetch_or(&vcpu_info->evtchn_upcall_pending, 1)) {
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return 0;
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}
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inject_callback(s, s->port_table[port].vcpu);
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return 0;
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}
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static int do_unmask_port_compat(XenEvtchnState *s, evtchn_port_t port,
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bool do_unmask,
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struct compat_shared_info *shinfo,
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struct compat_vcpu_info *vcpu_info)
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{
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const int bits_per_word = BITS_PER_BYTE * sizeof(shinfo->evtchn_pending[0]);
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typeof(shinfo->evtchn_pending[0]) mask;
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int idx = port / bits_per_word;
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int offset = port % bits_per_word;
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mask = 1UL << offset;
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if (idx >= bits_per_word) {
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return -EINVAL;
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}
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if (do_unmask) {
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/*
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* If this is a true unmask operation, clear the mask bit. If
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* it was already unmasked, we have nothing further to do.
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*/
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if (!((qatomic_fetch_and(&shinfo->evtchn_mask[idx], ~mask) & mask))) {
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return 0;
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}
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} else {
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/*
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* This is a pseudo-unmask for affinity changes. We don't
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* change the mask bit, and if it's *masked* we have nothing
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* else to do.
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*/
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if (qatomic_fetch_or(&shinfo->evtchn_mask[idx], 0) & mask) {
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return 0;
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}
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}
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/* If the event was not pending, we're done. */
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if (!(qatomic_fetch_or(&shinfo->evtchn_pending[idx], 0) & mask)) {
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return 0;
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}
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/* Now on to the vcpu_info evtchn_pending_sel index... */
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mask = 1UL << idx;
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/* If a port in this word was already pending for this vCPU, all done. */
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if (qatomic_fetch_or(&vcpu_info->evtchn_pending_sel, mask) & mask) {
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return 0;
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}
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/* Set evtchn_upcall_pending for this vCPU */
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if (qatomic_fetch_or(&vcpu_info->evtchn_upcall_pending, 1)) {
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return 0;
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}
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inject_callback(s, s->port_table[port].vcpu);
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return 0;
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}
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static int unmask_port(XenEvtchnState *s, evtchn_port_t port, bool do_unmask)
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{
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void *vcpu_info, *shinfo;
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if (s->port_table[port].type == EVTCHNSTAT_closed) {
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return -EINVAL;
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}
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shinfo = xen_overlay_get_shinfo_ptr();
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if (!shinfo) {
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return -ENOTSUP;
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}
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vcpu_info = kvm_xen_get_vcpu_info_hva(s->port_table[port].vcpu);
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if (!vcpu_info) {
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return -EINVAL;
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}
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if (xen_is_long_mode()) {
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return do_unmask_port_lm(s, port, do_unmask, shinfo, vcpu_info);
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} else {
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return do_unmask_port_compat(s, port, do_unmask, shinfo, vcpu_info);
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}
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}
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static int clear_port_pending(XenEvtchnState *s, evtchn_port_t port)
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{
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void *p = xen_overlay_get_shinfo_ptr();
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@ -380,3 +533,25 @@ int xen_evtchn_close_op(struct evtchn_close *close)
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return ret;
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}
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int xen_evtchn_unmask_op(struct evtchn_unmask *unmask)
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{
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XenEvtchnState *s = xen_evtchn_singleton;
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int ret;
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if (!s) {
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return -ENOTSUP;
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}
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if (!valid_port(unmask->port)) {
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return -EINVAL;
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}
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qemu_mutex_lock(&s->port_lock);
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ret = unmask_port(s, unmask->port, true);
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qemu_mutex_unlock(&s->port_lock);
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return ret;
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}
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@ -17,7 +17,9 @@ int xen_evtchn_set_callback_param(uint64_t param);
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struct evtchn_status;
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struct evtchn_close;
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struct evtchn_unmask;
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int xen_evtchn_status_op(struct evtchn_status *status);
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int xen_evtchn_close_op(struct evtchn_close *close);
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int xen_evtchn_unmask_op(struct evtchn_unmask *unmask);
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#endif /* QEMU_XEN_EVTCHN_H */
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@ -817,6 +817,18 @@ static bool kvm_xen_hcall_evtchn_op(struct kvm_xen_exit *exit, X86CPU *cpu,
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err = xen_evtchn_close_op(&close);
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break;
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}
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case EVTCHNOP_unmask: {
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struct evtchn_unmask unmask;
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qemu_build_assert(sizeof(unmask) == 4);
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if (kvm_copy_from_gva(cs, arg, &unmask, sizeof(unmask))) {
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err = -EFAULT;
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break;
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}
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err = xen_evtchn_unmask_op(&unmask);
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break;
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}
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default:
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return false;
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}
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