[PATCH] KVM: PPC: Book3S HV: Fix reverse map real-mode address lookup with huge vmalloc

[Christophe Leroy]

Nicholas Piggin <npiggin at gmail.com> a écrit :

> real_vmalloc_addr() does not currently work for huge vmalloc, which is
> what the reverse map can be allocated with for radix host, hash guest.
>
> Add huge page awareness to the function.
>
> Fixes: 8abddd968a30 ("powerpc/64s/radix: Enable huge vmalloc mappings")
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
>  arch/powerpc/kvm/book3s_hv_rm_mmu.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c  
> b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> index 7af7c70f1468..5f68cb5cc009 100644
> --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> @@ -26,16 +26,23 @@
>  static void *real_vmalloc_addr(void *x)
>  {
>  	unsigned long addr = (unsigned long) x;
> +	unsigned long mask;
> +	int shift;
>  	pte_t *p;
> +
>  	/*
> -	 * assume we don't have huge pages in vmalloc space...
> -	 * So don't worry about THP collapse/split. Called
> -	 * Only in realmode with MSR_EE = 0, hence won't need irq_save/restore.
> +	 * This is called only in realmode with MSR_EE = 0, hence won't need
> +	 * irq_save/restore around find_init_mm_pte.
>  	 */
> -	p = find_init_mm_pte(addr, NULL);
> +	p = find_init_mm_pte(addr, &shift);
>  	if (!p || !pte_present(*p))
>  		return NULL;
> -	addr = (pte_pfn(*p) << PAGE_SHIFT) | (addr & ~PAGE_MASK);
> +	if (!shift)
> +		shift = PAGE_SHIFT;
> +
> +	mask = (1UL << shift) - 1;
> +	addr = (pte_pfn(*p) << PAGE_SHIFT) | (addr & mask);

Looks strange, before we have ~MASK now we have mask without the ~

Also use PFN_PHYS() instead of open coding ?




> +
>  	return __va(addr);
>  }
>
> --
> 2.23.0