Hi Mike,

>
> The memory size calculation in kvm_cma_reserve() traverses memblock.memory
> rather than simply call memblock_phys_mem_size(). The comment in that
> function suggests that at some point there should have been call to
> memblock_analyze() before memblock_phys_mem_size() could be used.
> As of now, there is no memblock_analyze() at all and
> memblock_phys_mem_size() can be used as soon as cold-plug memory is
> registerd with memblock.
>
> Replace loop over memblock.memory with a call to memblock_phys_mem_size().
>
> Signed-off-by: Mike Rapoport <r...@linux.ibm.com>
> ---
>  arch/powerpc/kvm/book3s_hv_builtin.c | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c 
> b/arch/powerpc/kvm/book3s_hv_builtin.c
> index 7cd3cf3d366b..56ab0d28de2a 100644
> --- a/arch/powerpc/kvm/book3s_hv_builtin.c
> +++ b/arch/powerpc/kvm/book3s_hv_builtin.c
> @@ -95,22 +95,15 @@ EXPORT_SYMBOL_GPL(kvm_free_hpt_cma);
>  void __init kvm_cma_reserve(void)
>  {
>       unsigned long align_size;
> -     struct memblock_region *reg;
> -     phys_addr_t selected_size = 0;
> +     phys_addr_t selected_size;
>  
>       /*
>        * We need CMA reservation only when we are in HV mode
>        */
>       if (!cpu_has_feature(CPU_FTR_HVMODE))
>               return;
> -     /*
> -      * We cannot use memblock_phys_mem_size() here, because
> -      * memblock_analyze() has not been called yet.
> -      */
> -     for_each_memblock(memory, reg)
> -             selected_size += memblock_region_memory_end_pfn(reg) -
> -                              memblock_region_memory_base_pfn(reg);
>  
> +     selected_size = PHYS_PFN(memblock_phys_mem_size());
>       selected_size = (selected_size * kvm_cma_resv_ratio / 100) << 
> PAGE_SHIFT;

I think this is correct, but PHYS_PFN does x >> PAGE_SHIFT and then the
next line does x << PAGE_SHIFT, so I think we could combine those two
lines as:

selected_size = PAGE_ALIGN(memblock_phys_mem_size() * kvm_cma_resv_ratio / 100);

(I think that might technically change it from aligning down to aligning
up but I don't think 1 page matters here.)

Kind regards,
Daniel


>       if (selected_size) {
>               pr_debug("%s: reserving %ld MiB for global area\n", __func__,
> -- 
> 2.26.2
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