2016-01-22 05:12+0000, Wu, Feng: >> From: Radim Krčmář [mailto:rkrcmar@xxxxxxxxxx] >> 2016-01-20 09:42+0800, Feng Wu: >>> - if (kvm_intr_is_single_vcpu_fast(kvm, irq, dest_vcpu)) >>> + if (kvm_intr_can_posting_fast(kvm, irq, dest_vcpu)) >>> return true; >> >> There is one pitfall: xAPIC flat logical broadcast returns false, > > Do you mean kvm_intr_can_posting_fast() returns false for > xAPIC flat logical lowest-priority broadcast? I did. > After carefully read the code for several times, I still cannot > find the reason, could you please give more hints? You are right, there isn't a problem in the code. > BTW, I noticed there is a "if(irq->dest_id == 0xFF) goto out;" in > this function, but it is for the physical dest mode. I am not > sure you mean this. I didn't check if my assumptions were wrong. I'm sorry. >> but lowest priority is defined for it (practically isn't a broadcast) and >> the rest of this function doesn't check for lowest priority, so the >> interrupt won't be posted. >> >> We could modify our _fast functions to cover 0xff in flat logical, but >> ignoring this case isn't bad either ... it can happen only with 8 VCPU >> guests. > > Could you please elaborate a bit more why only for the 8 VCPU guests? xAPIC flat logical doesn't forbid lowest priority broadcasts, but lowest priority delivery still needs to have all destinations enabled, which can only happen with 8 VCPUs. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
