From: Razvan Cojocaru <rcojocaru@bitdefender.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Wei Liu <wei.liu2@citrix.com>,
xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH V7 2/5] x86/mm: allocate logdirty_ranges for altp2ms
Date: Tue, 20 Nov 2018 12:02:10 +0200 [thread overview]
Message-ID: <286c5d63-3964-9587-f67e-16fb86da5970@bitdefender.com> (raw)
In-Reply-To: <5BF3CE5402000078001FDD83@prv1-mh.provo.novell.com>
On 11/20/18 11:05 AM, Jan Beulich wrote:
>>>> On 19.11.18 at 18:26, <rcojocaru@bitdefender.com> wrote:
>> For now, only do allocation/deallocation; keeping them in sync
>> will be done in subsequent patches.
>>
>> Logdirty synchronization will only be done for active altp2ms;
>> so allocate logdirty rangesets (copying the host logdirty
>> rangeset) when an altp2m is activated, and free it when
>> deactivated.
>>
>> Write a helper function to do altp2m activiation (appropriately
>> handling failures). Also, refactor p2m_reset_altp2m() so that it
>> can be used to remove redundant codepaths, fixing the locking
>> while we’re at it.
>
> Perhaps this should have been a separate patch again, such
> that e.g. ...
>
>> +static void p2m_reset_altp2m(struct domain *d, unsigned int idx,
>> + enum altp2m_reset_type reset_type)
>> +{
>> + struct p2m_domain *p2m;
>> +
>> + ASSERT(idx < MAX_ALTP2M);
>> + p2m = d->arch.altp2m_p2m[idx];
>> +
>> + p2m_lock(p2m);
>> +
>> + p2m_flush_table_locked(p2m);
>> +
>> + if ( reset_type == ALTP2M_DEACTIVATE )
>> + p2m_free_logdirty(p2m);
>> +
>> + /* Uninit and reinit ept to force TLB shootdown */
>> + ept_p2m_uninit(p2m);
>> + ept_p2m_init(p2m);
>> +
>> + p2m->min_remapped_gfn = gfn_x(INVALID_GFN);
>> + p2m->max_remapped_gfn = 0;
>
> ... the addition of these can be properly associated with either
> part of the change. Looking at the code you remove from e.g.
> p2m_flush_altp2m() it's not part of the refactoring, but of what
> this patch's actual purpose is. But this is guesswork of mine
> without the split and without the addition getting explained,
> not the least because this getting moved here from the original
> instance of the function might also mean that it's part of the
> refactoring, but would then need to be done only in the
> ALTP2M_RESET case.
If you mean that p2m->min_remapped_gfn = gfn_x(INVALID_GFN); and
p2m->max_remapped_gfn = 0; should only happen on the ALTP2M_RESET case,
while that is technically true (and should follow from a verbatim
refactoring), George has pointed out that the assignments are in that
case unnecessary but harmless, and so the conditional is not worth it.
I can add the if and treat the RESET case explicitly if that's required.
Thanks,
Razvan
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next prev parent reply other threads:[~2018-11-20 10:02 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-19 17:26 (no subject) Razvan Cojocaru
2018-11-19 17:26 ` [PATCH V7 1/5] x86/mm: introduce p2m_{init, free}_logdirty() Razvan Cojocaru
2018-11-19 17:26 ` [PATCH V7 2/5] x86/mm: allocate logdirty_ranges for altp2ms Razvan Cojocaru
2018-11-20 9:05 ` Jan Beulich
2018-11-20 10:02 ` Razvan Cojocaru [this message]
2018-11-20 10:27 ` Jan Beulich
2018-11-20 10:29 ` Razvan Cojocaru
2018-11-19 17:26 ` [PATCH V7 3/5] x86/altp2m: fix display frozen when switching to a new view early Razvan Cojocaru
2018-11-20 9:12 ` Jan Beulich
2018-11-20 9:30 ` Razvan Cojocaru
2018-11-20 9:43 ` George Dunlap
2018-11-20 10:03 ` Jan Beulich
2018-11-19 17:26 ` [PATCH V7 4/5] p2m: Always use hostp2m when clipping rangesets Razvan Cojocaru
2018-11-19 17:26 ` [PATCH V7 5/5] p2m: change_range_type: Only invalidate mapped gfns Razvan Cojocaru
2018-11-19 17:34 ` (no subject) Razvan Cojocaru
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