On 26/03/2020 15:24, Alexandru Elisei wrote:
> From PCI Local Bus Specification Revision 3.0. section 3.8 "64-Bit Bus
> Extension":
>
> "The bandwidth requirements for I/O and configuration transactions cannot
> justify the added complexity, and, therefore, only memory transactions
> support 64-bit data transfers".
>
> Further down, the spec also describes the possible responses of a target
> which has been requested to do a 64-bit transaction. Limit the transaction
> to the lower 32 bits, to match the second accepted behaviour.
That looks like a reasonable behaviour.
AFAICS there is one code path from powerpc/spapr_pci.c which isn't
covered by those limitations (rtas_ibm_write_pci_config() ->
pci__config_wr() -> cfg_ops.write() -> vfio_pci_cfg_write()).
Same for read.
I am not sure we really care, maybe you can fix it if you like.
Either way this patch seems right, so:
> Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>
Cheers,
Andre
> ---
> pci.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/pci.c b/pci.c
> index 7399c76c0819..611e2c0bf1da 100644
> --- a/pci.c
> +++ b/pci.c
> @@ -119,6 +119,9 @@ static bool pci_config_data_out(struct ioport *ioport, struct kvm_cpu *vcpu, u16
> {
> union pci_config_address pci_config_address;
>
> + if (size > 4)
> + size = 4;
> +
> pci_config_address.w = ioport__read32(&pci_config_address_bits);
> /*
> * If someone accesses PCI configuration space offsets that are not
> @@ -135,6 +138,9 @@ static bool pci_config_data_in(struct ioport *ioport, struct kvm_cpu *vcpu, u16
> {
> union pci_config_address pci_config_address;
>
> + if (size > 4)
> + size = 4;
> +
> pci_config_address.w = ioport__read32(&pci_config_address_bits);
> /*
> * If someone accesses PCI configuration space offsets that are not
> @@ -248,6 +254,9 @@ static void pci_config_mmio_access(struct kvm_cpu *vcpu, u64 addr, u8 *data,
> cfg_addr.w = (u32)addr;
> cfg_addr.enable_bit = 1;
>
> + if (len > 4)
> + len = 4;
> +
> if (is_write)
> pci__config_wr(kvm, cfg_addr, data, len);
> else
>
