Re: [Xen-devel] [PATCH v2] tools: libxc: flush data cache after loading images into guest memory

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2013-12-12 at 14:23 +0000, Ian Campbell wrote:
> +#elif defined(__aarch64__)
> +    unsigned long start = (unsigned long)ptr;
> +    unsigned long end = start + nr;
> +    unsigned long p, ctr;
> +    int stride;
> +
> +    /* Flush cache using direct DC CVAC instructions. This is
> +     * available to EL0 when SCTLR_EL1.UCI is set, which Linux does.
> +     *
> +     * Bits 19:16 of CTR_EL0 are log2 of the minimum dcache line size
> +     * in words, which we use as our stride length. This is readable
> +     * with SCTLR_EL1.UCT is set, which Linux does.
> +     */
> +    asm volatile ("mrs %0, ctr_el0" : "=r" (ctr));
> +
> +    stride = 4 * (1 << ((ctr & 0xf0000UL) >> 16));
> +
> +    for ( p = start ; p < end ; p += stride )
> +        asm volatile ("dc cvac, %0" :  : "r" (p));

I wonder if I need a dsb here. I suspect I do.

Ian.


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