Re: [PATCH] kvm: consistently return 0/-errno from kvm_convert_memory

[Xiaoyao Li]

On 12/12/2024 11:57 PM, Paolo Bonzini wrote:
> In case of incorrect parameters, kvm_convert_memory() was returning
> -1 instead of -EINVAL.  The guest won't notice because it will move
> anyway to RUN_STATE_INTERNAL_ERROR, but fix this for consistency and
> clarity.

I think we need add more clarification about "guest".

kvm_convert_memory() is also used to service the request of 
KVM_HC_MAP_GPA_RANGE from guest since commit 47e76d03b155 ("i386/kvm: 
Add KVM_EXIT_HYPERCALL handling for KVM_HC_MAP_GPA_RANGE"). It might 
need to return error back to guest in case of incorrect parameters, in 
the future.

For the code change,

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>

> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   accel/kvm/kvm-all.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index 4c5cef766ad..81821af7d7a 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -2998,17 +2998,17 @@ int kvm_convert_memory(hwaddr start, hwaddr size, bool 
> to_private)
>       ram_addr_t offset;
>       MemoryRegion *mr;
>       RAMBlock *rb;
> -    int ret = -1;
> +    int ret = -EINVAL;
>   
>       trace_kvm_convert_memory(start, size, to_private ? "shared_to_private" : "private_to_shared");
>   
>       if (!QEMU_PTR_IS_ALIGNED(start, qemu_real_host_page_size()) ||
>           !QEMU_PTR_IS_ALIGNED(size, qemu_real_host_page_size())) {
> -        return -1;
> +        return ret;
>       }
>   
>       if (!size) {
> -        return -1;
> +        return ret;
>       }
>   
>       section = memory_region_find(get_system_memory(), start, size);
> @@ -3026,7 +3026,7 @@ int kvm_convert_memory(hwaddr start, hwaddr size, bool 
> to_private)
>           if (!to_private) {
>               return 0;
>           }
> -        return -1;
> +        return ret;
>       }
>   
>       if (!memory_region_has_guest_memfd(mr)) {