Re: [PATCH 5/5] hw/vfio/pci: Re-order pre-reset

[Eric Auger <eric.auger@redhat.com>]

On 2/20/25 11:48 PM, Alex Williamson wrote:
> We want the device in the D0 power state going into reset, but the
> config write can enable the BARs in the address space, which are
> then removed from the address space once we clear the memory enable
> bit in the command register.  Re-order to clear the command bit
> first, so the power state change doesn't enable the BARs.
>
> Cc: Cédric Le Goater <clg@redhat.com>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric
> ---
>  hw/vfio/pci.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index ba4ef65b16fa..fcc5f118bf90 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -2405,6 +2405,15 @@ void vfio_pci_pre_reset(VFIOPCIDevice *vdev)
>  
>      vfio_disable_interrupts(vdev);
>  
> +    /*
> +     * Stop any ongoing DMA by disconnecting I/O, MMIO, and bus master.
> +     * Also put INTx Disable in known state.
> +     */
> +    cmd = vfio_pci_read_config(pdev, PCI_COMMAND, 2);
> +    cmd &= ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER |
> +             PCI_COMMAND_INTX_DISABLE);
> +    vfio_pci_write_config(pdev, PCI_COMMAND, cmd, 2);
> +
>      /* Make sure the device is in D0 */
>      if (pdev->pm_cap) {
>          uint16_t pmcsr;
> @@ -2424,15 +2433,6 @@ void vfio_pci_pre_reset(VFIOPCIDevice *vdev)
>              }
>          }
>      }
> -
> -    /*
> -     * Stop any ongoing DMA by disconnecting I/O, MMIO, and bus master.
> -     * Also put INTx Disable in known state.
> -     */
> -    cmd = vfio_pci_read_config(pdev, PCI_COMMAND, 2);
> -    cmd &= ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER |
> -             PCI_COMMAND_INTX_DISABLE);
> -    vfio_pci_write_config(pdev, PCI_COMMAND, cmd, 2);
>  }
>  
>  void vfio_pci_post_reset(VFIOPCIDevice *vdev)