On 12.03.2023 08:54, Huang Rui wrote:
> From: Chen Jiqian <jiqian.c...@amd.com>
>
> When dom0 is PVH and we want to passthrough gpu to guest,
> we should allow BAR writes even through BAR is mapped. If
> not, the value of BARs are not initialized when guest firstly
> start.
>From this it doesn't become clear why a GPU would be special in this
regard, or what (if any) prior bug there was. Are you suggesting ...
> --- a/xen/drivers/vpci/header.c
> +++ b/xen/drivers/vpci/header.c
> @@ -392,7 +392,7 @@ static void cf_check bar_write(
> * Xen only cares whether the BAR is mapped into the p2m, so allow BAR
> * writes as long as the BAR is not mapped into the p2m.
> */
> - if ( bar->enabled )
> + if ( pci_conf_read16(pdev->sbdf, PCI_COMMAND) & PCI_COMMAND_MEMORY )
> {
> /* If the value written is the current one avoid printing a warning.
> */
> if ( val != (uint32_t)(bar->addr >> (hi ? 32 : 0)) )
... bar->enabled doesn't properly reflect the necessary state? It
generally shouldn't be necessary to look at the physical device's
state here.
Furthermore when you make a change in a case like this, the
accompanying comment also needs updating (which might have clarified
what, if anything, has been wrong).
Jan
