From: George Dunlap <george.dunlap@citrix.com>
To: Razvan Cojocaru <rcojocaru@bitdefender.com>,
xen-devel@lists.xenproject.org
Cc: "George Dunlap" <george.dunlap@eu.citrix.com>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Wei Liu" <wei.liu2@citrix.com>,
"Jan Beulich" <jbeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH V11 4/5] p2m: Always use hostp2m when clipping rangesets
Date: Thu, 20 Dec 2018 16:31:23 +0000 [thread overview]
Message-ID: <ea30fe84-5fee-3a57-8500-23c55e3e6e2b@citrix.com> (raw)
In-Reply-To: <1544001488-23763-5-git-send-email-rcojocaru@bitdefender.com>
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.dunlap@citrix.com>
> Signed-off-by: Razvan Cojocaru <rcojocaru@bitdefender.com>
> Tested-by: Tamas K Lengyel <tamas@tklengyel.com>
>
> ---
> CC: George Dunlap <george.dunlap@eu.citrix.com>
> CC: Jan Beulich <jbeulich@suse.com>
> CC: Andrew Cooper <andrew.cooper3@citrix.com>
> CC: Wei Liu <wei.liu2@citrix.com>
> CC: "Roger Pau Monné" <roger.pau@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;
> +
> + if ( start >= host_max_pfn )
> + printk(XENLOG_G_WARNING "Dom%d logdirty rangeset clipped to max_mapped_pfn\n",
> + d->domain_id);
> +
> + /* Always clip the rangeset down to the host p2m. */
> + if ( unlikely(end > host_max_pfn) )
> + end = host_max_pfn;
> +
> + /* If the requested range is out of scope, return doing nothing. */
> + if ( start > end )
> + return;
> +
> + /*
> + * If all valid gfns are in the invalidation range, just do a
> + * global type change. Otherwise, invalidate only the range we
> + * need.
> + */
> + if ( !start && end >= p2m->max_mapped_pfn )
> + p2m->change_entry_type_global(p2m, ot, nt);
> + else
> + rc = p2m->change_entry_type_range(p2m, ot, nt, start, end);
> +
> if ( rc )
> {
> - printk(XENLOG_G_ERR "Error %d changing Dom%d GFNs [%lx,%lx] from %d to %d\n",
> - rc, d->domain_id, start, end - 1, ot, nt);
> + printk(XENLOG_G_ERR "Error %d changing Dom%d GFNs [%lx,%lx) from %d to %d\n",
> + rc, d->domain_id, start, end, ot, nt);
Nitpick: This is printk is also wrong ATM: It uses [..), which would
indicate that the last value was exclusive. And it was when we weren't
modifying end; but with the `--end` at the top, the range is now inclusive.
Whatever we end up doing with `end`, this should match. If we name the
argument as end_exclusive, I'd say leave the string and use
end_exclusive here.
-George
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next prev parent reply other threads:[~2018-12-20 16:45 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-05 9:18 [PATCH V11 0/5] Fix VGA logdirty related display freezes with altp2m Razvan Cojocaru
2018-12-05 9:18 ` [PATCH V11 1/5] x86/p2m: allocate logdirty_ranges for altp2ms Razvan Cojocaru
2018-12-05 9:18 ` [PATCH V11 2/5] x86/p2m: refactor p2m_reset_altp2m() Razvan Cojocaru
2018-12-05 9:18 ` [PATCH V11 3/5] x86/altp2m: fix display frozen when switching to a new view early Razvan Cojocaru
2018-12-20 15:31 ` George Dunlap
2018-12-05 9:18 ` [PATCH V11 4/5] p2m: Always use hostp2m when clipping rangesets Razvan Cojocaru
2018-12-05 16:30 ` Jan Beulich
2018-12-13 10:22 ` Razvan Cojocaru
2018-12-13 10:43 ` Jan Beulich
2018-12-19 17:26 ` George Dunlap
2018-12-20 8:20 ` Jan Beulich
2018-12-20 12:59 ` George Dunlap
2018-12-20 13:52 ` Jan Beulich
2018-12-20 14:38 ` George Dunlap
2018-12-20 14:49 ` Jan Beulich
2018-12-20 15:14 ` Razvan Cojocaru
2018-12-20 15:22 ` George Dunlap
2018-12-20 15:01 ` Jan Beulich
2018-12-20 16:09 ` George Dunlap
2018-12-20 16:25 ` Razvan Cojocaru
2018-12-20 16:31 ` George Dunlap [this message]
2018-12-20 16:46 ` Razvan Cojocaru
2018-12-05 9:18 ` [PATCH V11 5/5] p2m: change_type_range: Only invalidate mapped gfns Razvan Cojocaru
2018-12-20 16:17 ` George Dunlap
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