On Fri, Mar 20, 2026 at 4:20 PM Sourav Poddar <[email protected]> wrote: > > hyperv_is_synic_enabled() is a global flag that returns true after the > first CPU initializes SynIC. With -smp N, all subsequent CPUs skip > hyperv_x86_synic_add(), leaving them without a synic object. This causes > get_synic() to return NULL, making hyperv_sint_route_new() fail and > triggering an assertion crash in hyperv_testdev. > > Fix by introducing hyperv_is_synic_present() which checks per-CPU > whether a synic object is already attached instead of using the global > flag.
You may want to rebase this on top of fhttps://mail.gnu.org/archive/html/qemu-devel/2026-03/msg05998.html and then fix hyperv_enable_synic() > > Fixes: c4cf32fc63f1 ("kvm/hyperv: add synic feature to CPU only if its not > enabled") > Reported-by: Xudong Hao > Signed-off-by: Sourav Poddar <[email protected]> > --- > hw/hyperv/hyperv.c | 5 +++++ > include/hw/hyperv/hyperv.h | 1 + > target/i386/kvm/kvm.c | 2 +- > 3 files changed, 7 insertions(+), 1 deletion(-) > > diff --git a/hw/hyperv/hyperv.c b/hw/hyperv/hyperv.c > index 27e323a819..ff53cbc699 100644 > --- a/hw/hyperv/hyperv.c > +++ b/hw/hyperv/hyperv.c > @@ -60,6 +60,11 @@ static SynICState *get_synic(CPUState *cs) > return SYNIC(object_resolve_path_component(OBJECT(cs), "synic")); > } > > +bool hyperv_is_synic_present(CPUState *cs) > +{ > + return get_synic(cs) != NULL; > +} > + > static void synic_update(SynICState *synic, bool sctl_enable, > hwaddr msg_page_addr, hwaddr event_page_addr) > { > diff --git a/include/hw/hyperv/hyperv.h b/include/hw/hyperv/hyperv.h > index 63a8b65278..23091301d0 100644 > --- a/include/hw/hyperv/hyperv.h > +++ b/include/hw/hyperv/hyperv.h > @@ -81,6 +81,7 @@ void hyperv_synic_reset(CPUState *cs); > void hyperv_synic_update(CPUState *cs, bool enable, > hwaddr msg_page_addr, hwaddr event_page_addr); > bool hyperv_is_synic_enabled(void); > +bool hyperv_is_synic_present(CPUState *cs); > > /* > * Process HVCALL_RESET_DEBUG_SESSION hypercall. > diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c > index a29f757c16..f5faf32606 100644 > --- a/target/i386/kvm/kvm.c > +++ b/target/i386/kvm/kvm.c > @@ -1754,7 +1754,7 @@ static int hyperv_init_vcpu(X86CPU *cpu) > return ret; > } > > - if (!hyperv_is_synic_enabled()) { > + if (!hyperv_is_synic_present(CPU(cpu))) { > ret = hyperv_x86_synic_add(cpu); > if (ret < 0) { > error_report("failed to create HyperV SynIC: %s", > -- > 2.53.0 >
