Re: [Xen-devel] [PATCH for 4.7] Remove HVMMEM_mmio_write_dm from the public interface.

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Yu Zhang [mailto:yu.c.zhang@xxxxxxxxxxxxxxx]
> Sent: 28 April 2016 09:30
> To: xen-devel@xxxxxxxxxxxxx
> Cc: zhiyuan.lv@xxxxxxxxx; Jan Beulich; Andrew Cooper; George Dunlap; Paul
> Durrant; Wei Liu
> Subject: [PATCH for 4.7] Remove HVMMEM_mmio_write_dm from the
> public interface.
> 
> HVMMEM_mmio_write_dm is removed for new xen interface versions, and
> is replaced with type HVMMEM_unused. Attempts to set a page to this
> type will return -EINVAL in xen after 4.7.0. And there will be no
> pages with type p2m_mmio_write_dm, therefore HVMOP_get_mem_type
> will
> never get the old type - HVMMEM_mmio_write_dm.
> 
> New approaches to write protect guest ram pages will be provided in
> future patches.
> 
> Signed-off-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>
> ---
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> Cc: Paul Durrant <paul.durrant@xxxxxxxxxx>

Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
> ---
>  xen/arch/x86/hvm/hvm.c          | 7 +++----
>  xen/include/public/hvm/hvm_op.h | 5 +++++
>  2 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 8cb6e9e..82e2ed1 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -5497,8 +5497,6 @@ long do_hvm_op(unsigned long op,
> XEN_GUEST_HANDLE_PARAM(void) arg)
>              get_gfn_query_unlocked(d, a.pfn, &t);
>              if ( p2m_is_mmio(t) )
>                  a.mem_type =  HVMMEM_mmio_dm;
> -            else if ( t == p2m_mmio_write_dm )
> -                a.mem_type = HVMMEM_mmio_write_dm;
>              else if ( p2m_is_readonly(t) )
>                  a.mem_type =  HVMMEM_ram_ro;
>              else if ( p2m_is_ram(t) )
> @@ -5529,7 +5527,7 @@ long do_hvm_op(unsigned long op,
> XEN_GUEST_HANDLE_PARAM(void) arg)
>              [HVMMEM_ram_rw]  = p2m_ram_rw,
>              [HVMMEM_ram_ro]  = p2m_ram_ro,
>              [HVMMEM_mmio_dm] = p2m_mmio_dm,
> -            [HVMMEM_mmio_write_dm] = p2m_mmio_write_dm
> +            [HVMMEM_unused] = p2m_invalid
>          };
> 
>          if ( copy_from_guest(&a, arg, 1) )
> @@ -5553,7 +5551,8 @@ long do_hvm_op(unsigned long op,
> XEN_GUEST_HANDLE_PARAM(void) arg)
>               ((a.first_pfn + a.nr - 1) > domain_get_maximum_gpfn(d)) )
>              goto setmemtype_fail;
> 
> -        if ( a.hvmmem_type >= ARRAY_SIZE(memtype) )
> +        if ( a.hvmmem_type >= ARRAY_SIZE(memtype) ||
> +             unlikely(a.hvmmem_type == HVMMEM_unused) )
>              goto setmemtype_fail;
> 
>          while ( a.nr > start_iter )
> diff --git a/xen/include/public/hvm/hvm_op.h
> b/xen/include/public/hvm/hvm_op.h
> index 1606185..ebb907a 100644
> --- a/xen/include/public/hvm/hvm_op.h
> +++ b/xen/include/public/hvm/hvm_op.h
> @@ -83,7 +83,12 @@ typedef enum {
>      HVMMEM_ram_rw,             /* Normal read/write guest RAM */
>      HVMMEM_ram_ro,             /* Read-only; writes are discarded */
>      HVMMEM_mmio_dm,            /* Reads and write go to the device model */
> +#if __XEN_INTERFACE_VERSION__ < 0x00040700
>      HVMMEM_mmio_write_dm       /* Read-only; writes go to the device
> model */
> +#else
> +    HVMMEM_unused              /* Placeholder; setting memory to this type
> +                                  will fail for code after 4.7.0 */
> +#endif
>  } hvmmem_type_t;
> 
>  /* Following tools-only interfaces may change in future. */
> --
> 1.9.1


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