On Tue, 12 Dec 2017, Julien Grall wrote:
> The function copy_to_guest can easily be extended to support zeroing
> guest VA. To avoid using a new bit, it is considered that a NULL buffer
> (i.e buf == NULL) means the guest memory will be zeroed.
>
> Lastly, reimplement raw_clear_guest using copy_to_guest.
>
> Signed-off-by: Julien Grall
Reviewed-by: Stefano Stabellini
> ---
> Changes in v3:
> - Use vaddr_t
> ---
> xen/arch/arm/guestcopy.c | 41 +++--
> 1 file changed, 11 insertions(+), 30 deletions(-)
>
> diff --git a/xen/arch/arm/guestcopy.c b/xen/arch/arm/guestcopy.c
> index 12fb03dd19..ff7d15380f 100644
> --- a/xen/arch/arm/guestcopy.c
> +++ b/xen/arch/arm/guestcopy.c
> @@ -31,7 +31,16 @@ static unsigned long copy_guest(void *buf, uint64_t addr,
> unsigned int len,
> p = __map_domain_page(page);
> p += offset;
> if ( flags & COPY_to_guest )
> -memcpy(p, buf, size);
> +{
> +/*
> + * buf will be NULL when the caller request to zero the
> + * guest memory.
> + */
> +if ( buf )
> +memcpy(p, buf, size);
> +else
> +memset(p, 0, size);
> +}
> else
> memcpy(buf, p, size);
>
> @@ -67,35 +76,7 @@ unsigned long raw_copy_to_guest_flush_dcache(void *to,
> const void *from,
>
> unsigned long raw_clear_guest(void *to, unsigned len)
> {
> -/* XXX needs to handle faults */
> -unsigned offset = (vaddr_t)to & ~PAGE_MASK;
> -
> -while ( len )
> -{
> -void *p;
> -unsigned size = min(len, (unsigned)PAGE_SIZE - offset);
> -struct page_info *page;
> -
> -page = get_page_from_gva(current, (vaddr_t) to, GV2M_WRITE);
> -if ( page == NULL )
> -return len;
> -
> -p = __map_domain_page(page);
> -p += offset;
> -memset(p, 0x00, size);
> -
> -unmap_domain_page(p - offset);
> -put_page(page);
> -len -= size;
> -to += size;
> -/*
> - * After the first iteration, guest virtual address is correctly
> - * aligned to PAGE_SIZE.
> - */
> -offset = 0;
> -}
> -
> -return 0;
> +return copy_guest(NULL, (vaddr_t)to, len, COPY_to_guest);
> }
>
> unsigned long raw_copy_from_guest(void *to, const void __user *from,
> unsigned len)
> --
> 2.11.0
>
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