On Thu, Mar 01, 2018 at 03:15:14PM +0100, Vitaly Kuznetsov wrote: > Hyper-V 2016 on KVM with SynIC enabled doesn't boot with the following > trace: > > kvm_entry: vcpu 0 > kvm_exit: reason MSR_WRITE rip 0xfffff8000131c1e5 info 0 0 > kvm_hv_synic_set_msr: vcpu_id 0 msr 0x40000090 data 0x10000 host 0 > kvm_msr: msr_write 40000090 = 0x10000 (#GP) > kvm_inj_exception: #GP (0x0) > > KVM acts according to the following statement from TLFS: > > " > 11.8.4 SINTx Registers > ... > Valid values for vector are 16-255 inclusive. Specifying an invalid > vector number results in #GP. > " > > However, I checked and genuine Hyper-V doesn't #GP when we write 0x10000 > to SINTx. I checked with Microsoft and they confirmed that if either the > Masked bit (bit 16) or the Polling bit (bit 18) is set to 1, then they > ignore the value of Vector. Make KVM act accordingly. > > Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> > --- > Changes since v1: > - Drop 'polling' bit check for now as we don't support this mode. We'll > need to bring some form of this check back when polling mode is > implemented [Roman Kagan]. > - Add a comment explaining "!host && !masked" in synic_set_sint() > --- > arch/x86/kvm/hyperv.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) Reviewed-by: Roman Kagan <rkagan@xxxxxxxxxxxxx>
