Re: [Xen-devel] [PATCH 1/2] vpci/msi: split code to bind pirq

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 08.05.18 at 11:25, <roger.pau@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/hvm/vmsi.c
> +++ b/xen/arch/x86/hvm/vmsi.c
> @@ -663,6 +663,42 @@ void vpci_msi_arch_mask(struct vpci_msi *msi, const 
> struct pci_dev *pdev,
>      vpci_mask_pirq(pdev->domain, msi->arch.pirq + entry, mask);
>  }
>  
> +static int vpci_msi_update(const struct pci_dev *pdev, uint32_t data,
> +                           uint64_t address, unsigned int vectors,
> +                           unsigned int pirq, uint32_t mask)
> +{
> +    unsigned int i;
> +
> +    ASSERT(pcidevs_locked());
> +
> +    for ( i = 0; i < vectors; i++ )
> +    {
> +        uint8_t vector = MASK_EXTR(data, MSI_DATA_VECTOR_MASK);
> +        uint8_t vector_mask = 0xff >> (8 - fls(vectors) + 1);
> +        struct xen_domctl_bind_pt_irq bind = {
> +            .machine_irq = pirq + i,
> +            .irq_type = PT_IRQ_TYPE_MSI,
> +            .u.msi.gvec = (vector & ~vector_mask) |
> +                          ((vector + i) & vector_mask),
> +            .u.msi.gflags = msi_gflags(data, address, (mask >> i) & 1),
> +        };
> +        int rc = pt_irq_create_bind(pdev->domain, &bind);
> +
> +        if ( rc )
> +        {
> +            gdprintk(XENLOG_ERR,
> +                     "%04x:%02x:%02x.%u: failed to bind PIRQ %u: %d\n",
> +                     pdev->seg, pdev->bus, PCI_SLOT(pdev->devfn),
> +                     PCI_FUNC(pdev->devfn), pirq + i, rc);
> +            while ( bind.machine_irq-- )
> +                pt_irq_destroy_bind(pdev->domain, &bind);

I realize this is just code movement, but is this while() correct? I think it
can only be correct if pirq (which bind.machine_irq gets initialized from)
was always zero, yet that doesn't look to be the case.

If you agree, I'd prefer fixed code to be moved (read: wants a prereq
patch), or for the fix to be applied while moving the code (suitably
reasoned about in the description).

Jan



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