Quoting Kalesh Singh (2022-03-07 10:48:59)
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index bc2aba953299..ccb2847ee2f4 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -457,22 +457,17 @@ int create_hyp_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
> return 0;
> }
>
> -static int __create_hyp_private_mapping(phys_addr_t phys_addr, size_t size,
> - unsigned long *haddr,
> - enum kvm_pgtable_prot prot)
> +
> +/**
> + * hyp_alloc_private_va_range - Allocates a private VA range.
> + * @size: The size of the VA range to reserve.
> + *
> + * The private VA range is allocated below io_map_base and
> + * aligned based on the order of @size.
Add what it returns?
Return: Start address of allocated VA range or some error value... (I don't
understand this part).
It may also be a good idea to write out what VA is in the description:
The private virtual address (VA) range is allocated below io_map_base
> + */
> +unsigned long hyp_alloc_private_va_range(size_t size)
> {
> unsigned long base;
> - int ret = 0;
> -
> - if (!kvm_host_owns_hyp_mappings()) {
> - base = kvm_call_hyp_nvhe(__pkvm_create_private_mapping,
> - phys_addr, size, prot);
> - if (IS_ERR_OR_NULL((void *)base))
> - return PTR_ERR((void *)base);
> - *haddr = base;
> -
> - return 0;
> - }
>
> mutex_lock(&kvm_hyp_pgd_mutex);
>
> @@ -484,29 +479,53 @@ static int __create_hyp_private_mapping(phys_addr_t phys_addr, size_t size,
> *
> * The allocated size is always a multiple of PAGE_SIZE.
> */
> - size = PAGE_ALIGN(size + offset_in_page(phys_addr));
> - base = io_map_base - size;
> + base = io_map_base - PAGE_ALIGN(size);
> +
> + /* Align the allocation based on the order of its size */
> + base = ALIGN_DOWN(base, PAGE_SIZE << get_order(size));
>
> /*
> * Verify that BIT(VA_BITS - 1) hasn't been flipped by
> * allocating the new area, as it would indicate we've
> * overflowed the idmap/IO address range.
> */
> - if ((base ^ io_map_base) & BIT(VA_BITS - 1))
> - ret = -ENOMEM;
> + if (!base || (base ^ io_map_base) & BIT(VA_BITS - 1))
> + base = (unsigned long)ERR_PTR(-ENOMEM);
It looks odd to use an error pointer casted to unsigned long to return
from an address allocation function. Why not pass a pointer for base
like the function was written before and return an int from this
function with 0 for success and negative error value? Otherwise some
sort of define should made like DMA_MAPPING_ERROR and that can be used
to indicate to the caller that the allocation failed, or a simple zero
may work?
> else
> io_map_base = base;
>
> mutex_unlock(&kvm_hyp_pgd_mutex);
>
> - if (ret)
> - goto out;
> + return base;
> +}
> +
> +static int __create_hyp_private_mapping(phys_addr_t phys_addr, size_t size,
> + unsigned long *haddr,
> + enum kvm_pgtable_prot prot)
> +{
> + unsigned long addr;
> + int ret = 0;
> +
> + if (!kvm_host_owns_hyp_mappings()) {
> + addr = kvm_call_hyp_nvhe(__pkvm_create_private_mapping,
> + phys_addr, size, prot);
> + if (IS_ERR((void *)addr))
IS_ERR_VALUE()?
> + return PTR_ERR((void *)addr);
> + *haddr = addr;
> +
> + return 0;
> + }
> +
> + size += offset_in_page(phys_addr);
> + addr = hyp_alloc_private_va_range(size);
> + if (IS_ERR((void *)addr))
IS_ERR_VALUE()?
> + return PTR_ERR((void *)addr);
>
> - ret = __create_hyp_mappings(base, size, phys_addr, prot);
> + ret = __create_hyp_mappings(addr, size, phys_addr, prot);
> if (ret)
> goto out;
>
> - *haddr = base + offset_in_page(phys_addr);
> + *haddr = addr + offset_in_page(phys_addr);
> out:
> return ret;
Would be simpler to remove the goto, or return early.
if (!ret)
*haddr = addr + offset_in_page(phys_addr);
return ret;
> }
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