2015-03-09 23:05-0600, James Sullivan: > Hi folks, > > This is a small patch that implements logic to handle the RH bit > being set in the msi message address register. Currently the DM bit is > the only thing used to decide irq->dest_mode (logical when DM set, > physical when unset). Documentation indicates that the DM bit will be > ignored when the RH bit is unset, and physical destination mode is used > in this case.
(I found that https://software.intel.com/en-us/forums/topic/288883 agrees with this definition of "ignored"; and it explains the weird design at the bottom.) > Fixed this to set irq->dest_mode to logical just when both bits are set, > and physical otherwise. > > Signed-off-by: James Sullivan <sullivan.jame...@gmail.com> > --- > diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c > @@ -97,18 +97,26 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct > kvm_lapic *src, > static inline void kvm_set_msi_irq(struct kvm_kernel_irq_routing_entry *e, > struct kvm_lapic_irq *irq) > { > + bool phys; > trace_kvm_msi_set_irq(e->msi.address_lo, e->msi.data); > > irq->dest_id = (e->msi.address_lo & > MSI_ADDR_DEST_ID_MASK) >> MSI_ADDR_DEST_ID_SHIFT; > irq->vector = (e->msi.data & > MSI_DATA_VECTOR_MASK) >> MSI_DATA_VECTOR_SHIFT; > - irq->dest_mode = (1 << MSI_ADDR_DEST_MODE_SHIFT) & e->msi.address_lo; > + /* > + * Set dest_mode to logical just in case both the RH and DM > + * bits are set, otherwise default to physical. > + */ > + phys = ((e->msi.address_lo & (MSI_ADDR_REDIRECTION_LOWPRI | > + MSI_ADDR_DEST_MODE_LOGICAL)) != > + (MSI_ADDR_REDIRECTION_LOWPRI | > + MSI_ADDR_DEST_MODE_LOGICAL)); > + irq->dest_mode = phys ? 0 : (MSI_ADDR_DEST_MODE_LOGICAL); (Should be APIC_DEST_LOGICAL. All works because it is a boolean and we only checked for APIC_DEST_PHYSICAL, which is 0.) > irq->trig_mode = (1 << MSI_DATA_TRIGGER_SHIFT) & e->msi.data; > irq->delivery_mode = e->msi.data & 0x700; > irq->level = 1; > irq->shorthand = 0; > - /* TODO Deal with RH bit of MSI message address */ RH bit still isn't deal with -- we do not use lowest-priority-like delivery in logical destination mode ... How does DM=1/RH=1 work on real hardware? (There seem to be interesting corner cases with irq->delivery_mode like APIC_DM_NMI.) Thanks. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
