Re: [Xen-devel] [RFC v1 07/15] vt-d: Add API to update IRTE when VT-d PI is used

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Wu, Feng
> Sent: Wednesday, March 25, 2015 8:32 PM
> 
> This patch adds an API which is used to update the IRTE
> for posted-interrupt when guest changes MSI/MSI-X information.
> 
> Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
> ---
>  xen/drivers/passthrough/vtd/intremap.c | 83
> ++++++++++++++++++++++++++++++++++
>  xen/drivers/passthrough/vtd/iommu.h    |  3 ++
>  xen/include/asm-x86/iommu.h            |  2 +
>  3 files changed, 88 insertions(+)
> 
> diff --git a/xen/drivers/passthrough/vtd/intremap.c
> b/xen/drivers/passthrough/vtd/intremap.c
> index 0333686..f44e74d 100644
> --- a/xen/drivers/passthrough/vtd/intremap.c
> +++ b/xen/drivers/passthrough/vtd/intremap.c
> @@ -898,3 +898,86 @@ void iommu_disable_x2apic_IR(void)
>      for_each_drhd_unit ( drhd )
>          disable_qinval(drhd->iommu);
>  }
> +
> +/*
> + * This function is used to update the IRTE for posted-interrupt
> + * when guest changes MSI/MSI-X information
> + */
> +int pi_update_irte(struct vcpu *v, struct pirq *pirq, uint32_t gvec )
> +{
> +    struct irq_desc *desc;
> +    struct msi_desc *msi_desc;
> +    int remap_index, rc = -1;
> +    struct pci_dev *pci_dev;
> +    struct acpi_drhd_unit *drhd;
> +    struct iommu *iommu;
> +    struct ir_ctrl *ir_ctrl;
> +    struct iremap_entry *iremap_entries = NULL, *p = NULL;
> +    struct iremap_entry new_ire;
> +    struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc;
> +    unsigned long flags;
> +
> +    desc = pirq_spin_lock_irq_desc(pirq, NULL);
> +    if ( !desc )
> +        return -1;
> +
> +    msi_desc = desc->msi_desc;
> +    if ( !msi_desc )
> +        goto unlock_out;
> +
> +    remap_index = msi_desc->remap_index;
> +    pci_dev = msi_desc->dev;
> +    if ( !pci_dev )
> +        goto unlock_out;
> +
> +    drhd = acpi_find_matched_drhd_unit(pci_dev);
> +    if (!drhd)
> +    {
> +        dprintk(XENLOG_INFO VTDPREFIX, "failed to get drhd!\n");
> +        goto unlock_out;
> +    }
> +
> +    iommu = drhd->iommu;
> +    ir_ctrl = iommu_ir_ctrl(iommu);
> +    if ( !ir_ctrl )
> +    {
> +        dprintk(XENLOG_INFO VTDPREFIX, "failed to get ir_ctrl!\n");
> +        goto unlock_out;
> +    }
> +
> +    spin_lock_irqsave(&ir_ctrl->iremap_lock, flags);
> +
> +    GET_IREMAP_ENTRY(ir_ctrl->iremap_maddr, remap_index,
> iremap_entries, p);
> +
> +    memcpy(&new_ire, p, sizeof(struct iremap_entry));
> +
> +    /* Setup/Update interrupt remapping table entry */
> +    new_ire.lo_intpost.urg = 0;
> +    new_ire.lo_intpost.vector = gvec;
> +    new_ire.lo_intpost.pda_l = (((u64)virt_to_maddr(pi_desc)) >>
> +                                (32 - PDA_LOW_BIT)) & ~(-1UL <<
> PDA_LOW_BIT);
> +    new_ire.hi_intpost.pda_h = (((u64)virt_to_maddr(pi_desc)) >>  32) &
> +                                ~(-1UL << PDA_HIGH_BIT);
> +
> +    new_ire.lo_intpost.res_1 = 0;
> +    new_ire.lo_intpost.res_2 = 0;
> +    new_ire.lo_intpost.res_3 = 0;
> +    new_ire.hi_intpost.res_1 = 0;
> +
> +    new_ire.lo_intpost.im = 1;
> +

Is above code for creating a new entry or updating an existing entry?
suppose two purposes would require different steps but here I didn't
see a difference... or if you mean every update is equal to what's
required for creating a new one, better add a comment for that.

Thanks
Kevin

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