Re: [PATCH v3 kvmtool 28/32] pci: Toggle BAR I/O and memory space emulation

["André Przywara" <andre.przywara@arm.com>]

On 26/03/2020 15:24, Alexandru Elisei wrote:
> During configuration of the BAR addresses, a Linux guest disables and
> enables access to I/O and memory space. When access is disabled, we don't
> stop emulating the memory regions described by the BARs. Now that we have
> callbacks for activating and deactivating emulation for a BAR region,
> let's use that to stop emulation when access is disabled, and
> re-activate it when access is re-enabled.
> 
> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>

Reviewed-by: Andre Przywara <andre.przywara@arm.com>

Cheers,
Andre

> ---
>  pci.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/pci.c b/pci.c
> index 4ace190898f2..c2860e6707fe 100644
> --- a/pci.c
> +++ b/pci.c
> @@ -163,6 +163,42 @@ static struct ioport_operations pci_config_data_ops = {
>  	.io_out	= pci_config_data_out,
>  };
>  
> +static void pci_config_command_wr(struct kvm *kvm,
> +				  struct pci_device_header *pci_hdr,
> +				  u16 new_command)
> +{
> +	int i;
> +	bool toggle_io, toggle_mem;
> +
> +	toggle_io = (pci_hdr->command ^ new_command) & PCI_COMMAND_IO;
> +	toggle_mem = (pci_hdr->command ^ new_command) & PCI_COMMAND_MEMORY;
> +
> +	for (i = 0; i < 6; i++) {
> +		if (!pci_bar_is_implemented(pci_hdr, i))
> +			continue;
> +
> +		if (toggle_io && pci__bar_is_io(pci_hdr, i)) {
> +			if (__pci__io_space_enabled(new_command))
> +				pci_hdr->bar_activate_fn(kvm, pci_hdr, i,
> +							 pci_hdr->data);
> +			else
> +				pci_hdr->bar_deactivate_fn(kvm, pci_hdr, i,
> +							   pci_hdr->data);
> +		}
> +
> +		if (toggle_mem && pci__bar_is_memory(pci_hdr, i)) {
> +			if (__pci__memory_space_enabled(new_command))
> +				pci_hdr->bar_activate_fn(kvm, pci_hdr, i,
> +							 pci_hdr->data);
> +			else
> +				pci_hdr->bar_deactivate_fn(kvm, pci_hdr, i,
> +							   pci_hdr->data);
> +		}
> +	}
> +
> +	pci_hdr->command = new_command;
> +}
> +
>  void pci__config_wr(struct kvm *kvm, union pci_config_address addr, void *data, int size)
>  {
>  	void *base;
> @@ -188,6 +224,12 @@ void pci__config_wr(struct kvm *kvm, union pci_config_address addr, void *data,
>  	if (*(u32 *)(base + offset) == 0)
>  		return;
>  
> +	if (offset == PCI_COMMAND) {
> +		memcpy(&value, data, size);
> +		pci_config_command_wr(kvm, pci_hdr, (u16)value);
> +		return;
> +	}
> +
>  	bar = (offset - PCI_BAR_OFFSET(0)) / sizeof(u32);
>  
>  	/*
>