Re: [Xen-devel] [PATCH v3 3/3] xen: rework paging_log_dirty_op to work with hvm guests

[Roger Pau Monnà <roger.pau@xxxxxxxxxx>]

El 10/04/15 a les 19.29, Roger Pau Monne ha escrit:
> When the caller of paging_log_dirty_op is a hvm guest Xen would choke when
> trying to copy the dirty bitmap to the guest because the paging lock is
> already held.
> 
> Fix this by independently mapping each page of the guest bitmap as needed
> without the paging lock held.
> 
> Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
> Cc: Tim Deegan <tim@xxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> Changes since v2:
>  - Add checks for p2m_is_ram and p2m_is_discard_write when mapping a guest
>    page.
>  - Remove error checking from memset/memcpy, they unconditionally return
>    dst.
> ---
>  xen/arch/x86/mm/paging.c | 103 
> +++++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 91 insertions(+), 12 deletions(-)
> 
> diff --git a/xen/arch/x86/mm/paging.c b/xen/arch/x86/mm/paging.c
> index b54d76a..cb5feb8 100644
> --- a/xen/arch/x86/mm/paging.c
> +++ b/xen/arch/x86/mm/paging.c
> @@ -397,6 +397,53 @@ int paging_mfn_is_dirty(struct domain *d, mfn_t gmfn)
>      return rv;
>  }
>  
> +static inline void *map_dirty_bitmap(XEN_GUEST_HANDLE_64(uint8) dirty_bitmap,
> +                                     unsigned long pages,
> +                                     struct page_info **page,
> +                                     unsigned long *mapped_page)
> +{
> +    p2m_type_t p2mt;
> +    uint32_t pfec;

This should be:

uint32_t pfec = PFEC_page_present | PFEC_write_access;

Will wait for other's comments before resending the series.

Roger.

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