On 12/5/18 9:18 AM, Razvan Cojocaru wrote:
> The logdirty rangesets of the altp2ms need to be kept in sync with the
> hostp2m. This means when iterating through the altp2ms, we need to
> use the host p2m to clip the rangeset, not the indiviual altp2m's
> value.
>
> This change also:
>
> - Documents that the end is non-inclusive
>
> - Calculates an "inclusive" value for the end once, rather than
> open-coding the modification, and (worse) back-modifying updates so
> that the calculation ends up correct
>
> - Clarifies the logic deciding whether to call
> change_entry_type_global() or change_entry_type_range()
>
> - Handles the case where start >= hostp2m->max_mapped_pfn
>
> Signed-off-by: George Dunlap <george.dun...@citrix.com>
> Signed-off-by: Razvan Cojocaru <rcojoc...@bitdefender.com>
> Tested-by: Tamas K Lengyel <ta...@tklengyel.com>
>
> ---
> CC: George Dunlap <george.dun...@eu.citrix.com>
> CC: Jan Beulich <jbeul...@suse.com>
> CC: Andrew Cooper <andrew.coop...@citrix.com>
> CC: Wei Liu <wei.l...@citrix.com>
> CC: "Roger Pau Monné" <roger....@citrix.com>
>
> ---
> Changes since V10:
> - Fixed a double-space in the patch description.
> - Fixed a coding style issue for
> "if ( !start && end >= p2m->max_mapped_pfn)" (no space before
> closing ')').
> - Switched the early return comment back to "/* If the requested
> range is out of scope, return doing nothing. */.
> - Added Tamas' Tested-by.
> ---
> xen/arch/x86/mm/p2m.c | 47 ++++++++++++++++++++++++++++++-----------------
> 1 file changed, 30 insertions(+), 17 deletions(-)
>
> diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
> index d145850..539ea16 100644
> --- a/xen/arch/x86/mm/p2m.c
> +++ b/xen/arch/x86/mm/p2m.c
> @@ -1002,30 +1002,43 @@ int p2m_change_type_one(struct domain *d, unsigned
> long gfn_l,
> return rc;
> }
>
> -/* Modify the p2m type of a range of gfns from ot to nt. */
> +/* Modify the p2m type of [start, end) from ot to nt. */
> static void change_type_range(struct p2m_domain *p2m,
> unsigned long start, unsigned long end,
> p2m_type_t ot, p2m_type_t nt)
> {
> - unsigned long gfn = start;
> struct domain *d = p2m->domain;
> + const unsigned long host_max_pfn = p2m_get_hostp2m(d)->max_mapped_pfn;
> int rc = 0;
>
> - if ( unlikely(end > p2m->max_mapped_pfn) )
> - {
> - if ( !gfn )
> - {
> - p2m->change_entry_type_global(p2m, ot, nt);
> - gfn = end;
> - }
> - end = p2m->max_mapped_pfn + 1;
> - }
> - if ( gfn < end )
> - rc = p2m->change_entry_type_range(p2m, ot, nt, gfn, end - 1);
> + --end;
I don't like the idea of modifying arguments, which is why I duplicated
them in the first place.
What about calling the argument end_exclusive, and having a local
variable, 'end', which we set to be end_exclusive-1?
> + if ( start >= host_max_pfn )
> + printk(XENLOG_G_WARNING "Dom%d logdirty rangeset clipped to
> max_mapped_pfn\n",
> + d->domain_id);
This doesn't seem to be the right condition for this warning.. Surely
this warning would go better under the next conditional, where we
actually do the clipping?
> + /* Always clip the rangeset down to the host p2m. */
> + if ( unlikely(end > host_max_pfn) )
> + end = host_max_pfn;
So what about modifying this comment thus:
"Always clip the rangeset down to the host p2m. This is probably not
the right behavior. This should be revisited later, but for now post a
warning."
Thanks,
-George
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