Re: [Xen-devel] [PATCH 03 of 14 V3] amd iommu: Add iommu emulation for hvm guest

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.01.12 at 18:07, Wei Wang <wei.wang2@xxxxxxx> wrote:
> +static unsigned long get_gfn_from_base_reg(uint64_t base_raw)
> +{ 
> +    uint64_t addr_lo, addr_hi, addr64;
> +
> +    addr_lo = iommu_get_addr_lo_from_reg(base_raw & DMA_32BIT_MASK);
> +    addr_hi = iommu_get_addr_hi_from_reg(base_raw >> 32);
> +    addr64 = (addr_hi << 32) | (addr_lo << PAGE_SHIFT);

I suppose that this isn't really correct - addr_lo shouldn't really
need any shifting, or else base_raw would be a pretty odd entity.
I'll convert the function to use reg_to_u64() instead. While I
won't do this, I then also wonder whether the first two operations
could be converted to u64_to_reg(), and if so, what the purpose
of the whole function is (it would then merely shift the input
value to obtain a frame number).

Jan

> +
> +    ASSERT ( addr64 != 0 );
> +
> +    return addr64 >> PAGE_SHIFT;
> +}



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