Re: [PATCH v2 1/2] x86: add p2m_mmio_write_dm

["Jan Beulich" <JBeulich@suse.com>]

>>> On 22.08.14 at 21:18, <wei.ye@intel.com> wrote:
> --- a/xen/arch/x86/mm/p2m-ept.c
> +++ b/xen/arch/x86/mm/p2m-ept.c
> @@ -127,6 +127,7 @@ static void ept_p2m_type_to_flags(ept_entry_t *entry, p2m_type_t type, p2m_acces
>          case p2m_ram_logdirty:
>          case p2m_ram_ro:
>          case p2m_ram_shared:
> +        case p2m_mmio_write_dm:
>              entry->r = entry->x = 1;
>              entry->w = 0;
>              break;

Is that really what you want? I.e. should such pages be executable?

> --- a/xen/arch/x86/mm/p2m-pt.c
> +++ b/xen/arch/x86/mm/p2m-pt.c
> @@ -98,6 +98,7 @@ static unsigned long p2m_type_to_flags(p2m_type_t t, mfn_t mfn)
>      case p2m_ram_ro:
>      case p2m_ram_logdirty:
>      case p2m_ram_shared:
> +    case p2m_mmio_write_dm:
>          return flags | P2M_BASE_FLAGS;

Same here - this would likely better be grouped with
p2m_grant_map_ro.

> --- a/xen/include/asm-x86/p2m.h
> +++ b/xen/include/asm-x86/p2m.h
> @@ -71,6 +71,7 @@ typedef enum {
>      p2m_ram_shared = 12,          /* Shared or sharable memory */
>      p2m_ram_broken = 13,          /* Broken page, access cause domain crash */
>      p2m_map_foreign  = 14,        /* ram pages from foreign domain */
> +    p2m_mmio_write_dm = 15,       /* Read-only; write go to the device model */
>  } p2m_type_t;

I'm still not really convinced introducing a new p2m type is the right
approach here, but I'll leave the final decision to Tim.

Jan