On Thu, Jun 12, 2014 at 09:30:10AM -0700, Victor Kamensky wrote:
> Fix vgic_bitmap_get_reg function to return 'right' word address of
> 'unsigned long' bitmap value in case of BE 64bit image.
>
> Signed-off-by: Victor Kamensky <victor.kamensky@xxxxxxxxxx>
> ---
> virt/kvm/arm/vgic.c | 24 ++++++++++++++++++++++--
> 1 file changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 529c336..b4ffd82 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -101,14 +101,34 @@ static u32 vgic_nr_lr;
>
> static unsigned int vgic_maint_irq;
>
> +/*
> + * struct vgic_bitmap contains unions that provide two views of
> + * the same data. In one case it is an array of registers of
> + * u32's, and in the other case it is a bitmap of unsigned
> + * longs.
> + *
> + * This does not work on 64-bit BE systems, because the bitmap access
> + * will store two consecutive 32-bit words with the higher-addressed
> + * register's bits at the lower index and the lower-addressed register's
> + * bits at the higher index.
> + *
> + * Therefore, swizzle the register index when accessing the 32-bit word
> + * registers to access the right register's value.
> + */
> +#if defined(CONFIG_CPU_BIG_ENDIAN) && BITS_PER_LONG == 64
> +#define REG_OFFSET_SWIZZLE 1
> +#else
> +#define REG_OFFSET_SWIZZLE 0
> +#endif
> +
> static u32 *vgic_bitmap_get_reg(struct vgic_bitmap *x,
> int cpuid, u32 offset)
> {
> offset >>= 2;
> if (!offset)
> - return x->percpu[cpuid].reg;
> + return x->percpu[cpuid].reg + (offset ^ REG_OFFSET_SWIZZLE);
> else
> - return x->shared.reg + offset - 1;
> + return x->shared.reg + ((offset - 1) ^ REG_OFFSET_SWIZZLE);
> }
>
> static int vgic_bitmap_get_irq_val(struct vgic_bitmap *x,
> --
> 1.8.1.4
>
I had wished there was a cleaner way to abstract this, but I can't think
of a cleaner solution, and restructuring the whole thing would be very
invasive.
I'm curious to hear from Marc on this one, but you can add:
Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
because it looks correct.
Thanks for picking up my suggestion on the commenting.
-Christoffer
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