On 12/02/2016 14:59, Suravee Suthikulpanit wrote:
> + "icrh:icrl=%#010x:%08x, id=%u, index=%u\n",
> + __func__, svm->vcpu.cpu, svm->vcpu.vcpu_id,
> + icrh, icrl, id, index);
> +
> + switch (id) {
> + case AVIC_INCMP_IPI_ERR_INVALID_INT_TYPE:
> + /*
> + * AVIC hardware handles the generation of
> + * IPIs when the specified Message Type is Fixed
> + * (also known as fixed delivery mode) and
> + * the Trigger Mode is edge-triggered. The hardware
> + * also supports self and broadcast delivery modes
> + * specified via the Destination Shorthand(DSH)
> + * field of the ICRL. Logical and physical APIC ID
> + * formats are supported. All other IPI types cause
> + * a #VMEXIT, which needs to emulated.
> + */
> + kvm_lapic_reg_write(apic, APIC_ICR2, icrh);
> + kvm_lapic_reg_write(apic, APIC_ICR, icrl);
> + break;
> + case AVIC_INCMP_IPI_ERR_TARGET_NOT_RUN:
> + kvm_lapic_reg_write(apic, APIC_ICR2, icrh);
> + kvm_lapic_reg_write(apic, APIC_ICR, icrl);
Wouldn't this cause a double injection of the IPI if the following happens:
1) destination 1 is running, so the processor sets IRR and sends a
doorbell message
2) destination 2 is not running, so the processor sets IRR and exits
3) destination 1 processes the interrupt, moving it from IRR to ISR
4) destination 1 sends an EOI
5) the source exits and reinjects the interrupt
6) destination 1 then receives the interrupt again.
Or alternatively:
1) destination 1 is not running, so the processor sets IRR and exits
2) another CPU executes VMRUN for destination 1, so the processor
injects the interrupt
3) destination 1 sends an EOI
4) the source exits and reinjects the interrupt
5) destination 1 then receives the interrupt again.
The handling of races for IsRunning and incomplete IPIs has always been
very confusing to me whenever I read the AVIC specification. It would
be great if you could clarify this.
Paolo
> + break;
> + case AVIC_INCMP_IPI_ERR_INV_TARGET:
> + pr_err("SVM: %s: Invalid IPI target (icr=%#08x:%08x, idx=%u)\n",
> + __func__, icrh, icrl, index);
> + BUG();
> + break;
> + case AVIC_INCMP_IPI_ERR_INV_BK_PAGE:
> + pr_err("SVM: %s: Invalid bk page (icr=%#08x:%08x, idx=%u)\n",
> + __func__, icrh, icrl, index);
> + BUG();
