Re: [Qemu-devel] [PATCH v6 01/17] pci: fix unaligned access in pci_xxx_quad()

[Michael S. Tsirkin]

On Mon, May 30, 2016 at 12:14:26PM +0300, Leonid Bloch wrote:
> From: Dmitry Fleytman <address@hidden>
> 
> Replace legacy cpu_to_le64w()/le64_to_cpup()
> calls with stq_le_p()/ldq_le_p().
> 
> Signed-off-by: Dmitry Fleytman <address@hidden>
> Signed-off-by: Leonid Bloch <address@hidden>

Could you please add a code comment to clarify what's going on a bit more?
Something to the point that capabilities are guaranteed to
be dword-aligned only.

Also, this isn't a dependency of this patchset I think -
as far as I could say the only user of this is
        pcie: Introduce function for DSN capability creation
but that merely accesses a capability, and all callers pass in
an aligned offset.

> ---
>  include/hw/pci/pci.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index ef6ba51..ee238ad 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -468,13 +468,13 @@ pci_get_long(const uint8_t *config)
>  static inline void
>  pci_set_quad(uint8_t *config, uint64_t val)
>  {
> -    cpu_to_le64w((uint64_t *)config, val);
> +    stq_le_p(config, val);
>  }
>  
>  static inline uint64_t
>  pci_get_quad(const uint8_t *config)
>  {
> -    return le64_to_cpup((const uint64_t *)config);
> +    return ldq_le_p(config);
>  }
>  
>  static inline void
> -- 
> 2.5.5