[PULL,05/26] hw/remote/vfio-user: Fix config space access byte order

Commit Message

Philippe Mathieu-Daudé May 8, 2024, 5:44 p.m. UTC

From: Mattias Nissler <[e-mail]>

PCI config space is little-endian, so on a big-endian host we need to
perform byte swaps for values as they are passed to and received from
the generic PCI config space access machinery.

Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>
Reviewed-by: Stefan Hajnoczi <[e-mail]>
Reviewed-by: Jagannathan Raman <[e-mail]>
Signed-off-by: Mattias Nissler <[e-mail]>
Message-ID: <[e-mail]>
Signed-off-by: Philippe Mathieu-Daudé <[e-mail]>
---
 hw/remote/vfio-user-obj.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Michael Tokarev May 10, 2024, 8:18 a.m. UTC | #1

08.05.2024 20:44, Philippe Mathieu-Daudé wrote:
> From: Mattias Nissler <[e-mail]>
> 
> PCI config space is little-endian, so on a big-endian host we need to
> perform byte swaps for values as they are passed to and received from
> the generic PCI config space access machinery.

Is this a material for stable?

Thanks,

/mjt

>   hw/remote/vfio-user-obj.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c
> index d9b879e056..8dbafafb9e 100644
> --- a/hw/remote/vfio-user-obj.c
> +++ b/hw/remote/vfio-user-obj.c
> @@ -281,7 +281,7 @@ static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, char * const buf,
>       while (bytes > 0) {
>           len = (bytes > pci_access_width) ? pci_access_width : bytes;
>           if (is_write) {
> -            memcpy(&val, ptr, len);
> +            val = ldn_le_p(ptr, len);
>               pci_host_config_write_common(o->pci_dev, offset,
>                                            pci_config_size(o->pci_dev),
>                                            val, len);
> @@ -289,7 +289,7 @@ static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, char * const buf,
>           } else {
>               val = pci_host_config_read_common(o->pci_dev, offset,
>                                                 pci_config_size(o->pci_dev), len);
> -            memcpy(ptr, &val, len);
> +            stn_le_p(ptr, len, val);
>               trace_vfu_cfg_read(offset, val);
>           }
>           offset += len;

Philippe Mathieu-Daudé May 10, 2024, 9:54 a.m. UTC | #2

On 10/5/24 10:18, Michael Tokarev wrote:
> 08.05.2024 20:44, Philippe Mathieu-Daudé wrote:
>> From: Mattias Nissler <[e-mail]>
>>
>> PCI config space is little-endian, so on a big-endian host we need to
>> perform byte swaps for values as they are passed to and received from
>> the generic PCI config space access machinery.
> 
> Is this a material for stable?

Yes, sorry for not adding the tag :\

> 
> Thanks,
> 
> /mjt

Patch

diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c
index d9b879e056..8dbafafb9e 100644
--- a/hw/remote/vfio-user-obj.c
+++ b/hw/remote/vfio-user-obj.c
@@ -281,7 +281,7 @@  static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, char * const buf,
     while (bytes > 0) {
         len = (bytes > pci_access_width) ? pci_access_width : bytes;
         if (is_write) {
-            memcpy(&val, ptr, len);
+            val = ldn_le_p(ptr, len);
             pci_host_config_write_common(o->pci_dev, offset,
                                          pci_config_size(o->pci_dev),
                                          val, len);
@@ -289,7 +289,7 @@  static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, char * const buf,
         } else {
             val = pci_host_config_read_common(o->pci_dev, offset,
                                               pci_config_size(o->pci_dev), len);
-            memcpy(ptr, &val, len);
+            stn_le_p(ptr, len, val);
             trace_vfu_cfg_read(offset, val);
         }
         offset += len;