Re: [PATCH V7 07/11] vpci/header: emulate PCI_COMMAND register for guests

[Oleksandr <olekstysh@xxxxxxxxx>]

On 26.07.22 18:30, Jan Beulich wrote:

Hello Jan

> On 19.07.2022 19:42, Oleksandr Tyshchenko wrote:
> > --- a/xen/drivers/vpci/header.c
> > +++ b/xen/drivers/vpci/header.c
> > @@ -443,11 +443,27 @@ static int modify_bars(const struct pci_dev *pdev, 
> > uint16_t cmd, bool rom_only)
> >       return 0;
> >   }
> >   
> > +/* TODO: Add proper emulation for all bits of the command register. */
> >   static void cf_check cmd_write(
> >       const struct pci_dev *pdev, unsigned int reg, uint32_t cmd, void *data)
> >   {
> >       uint16_t current_cmd = pci_conf_read16(pdev->sbdf, reg);
> >   
> > +    if ( !is_hardware_domain(pdev->domain) )
> > +    {
> > +        struct vpci_header *header = data;
> > +
> > +        header->guest_cmd = cmd;
> > +#ifdef CONFIG_HAS_PCI_MSI
> > +        if ( pdev->vpci->msi->enabled || pdev->vpci->msix->enabled )
> > +            /*
> > +             * Guest wants to enable INTx, but it can't be enabled
> > +             * if MSI/MSI-X enabled.
> > +             */
> > +            cmd |= PCI_COMMAND_INTX_DISABLE;
> > +#endif
> > +    }
> > +
> >       /*
> >        * Let Dom0 play with all the bits directly except for the memory
> >        * decoding one.
> > @@ -464,6 +480,19 @@ static void cf_check cmd_write(
> >           pci_conf_write16(pdev->sbdf, reg, cmd);
> >   }
> >   
> > +static uint32_t cf_check cmd_read(
> > +    const struct pci_dev *pdev, unsigned int reg, void *data)
> > +{
> > +    if ( !is_hardware_domain(pdev->domain) )
> > +    {
> > +        struct vpci_header *header = data;
> > +
> > +        return header->guest_cmd;
> > +    }
> > +
> > +    return pci_conf_read16(pdev->sbdf, reg);
> > +}
> This function wants the same leading comment as cmd_write().
ok


>   I also
> think you better wouldn't give the guest the impression that r/o bits
> can actually be written to (but getting this right may well fall
> under the TODO).
ok


> Jan
--
Regards,

Oleksandr Tyshchenko