From: "Jan Beulich" <JBeulich@suse.com>
To: Yu Zhang <yu.c.zhang@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>,
George Dunlap <george.dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
xen-devel@lists.xen.org, Paul Durrant <paul.durrant@citrix.com>,
zhiyuan.lv@intel.com, Jun Nakajima <jun.nakajima@intel.com>
Subject: Re: [PATCH v9 4/5] x86/ioreq server: Asynchronously reset outstanding p2m_ioreq_server entries.
Date: Fri, 24 Mar 2017 04:37:38 -0600 [thread overview]
Message-ID: <58D5050202000078001472FB@prv-mh.provo.novell.com> (raw)
In-Reply-To: <58D4E16F.4090004@linux.intel.com>
>>> On 24.03.17 at 10:05, <yu.c.zhang@linux.intel.com> wrote:
>
> On 3/23/2017 5:00 PM, Jan Beulich wrote:
>>>>> On 23.03.17 at 04:23, <yu.c.zhang@linux.intel.com> wrote:
>>> On 3/22/2017 10:29 PM, Jan Beulich wrote:
>>>>>>> On 21.03.17 at 03:52, <yu.c.zhang@linux.intel.com> wrote:
>>>>> --- a/xen/arch/x86/hvm/ioreq.c
>>>>> +++ b/xen/arch/x86/hvm/ioreq.c
>>>>> @@ -949,6 +949,14 @@ int hvm_map_mem_type_to_ioreq_server(struct domain *d,
> ioservid_t id,
>>>>>
>>>>> spin_unlock_recursive(&d->arch.hvm_domain.ioreq_server.lock);
>>>>>
>>>>> + if ( rc == 0 && flags == 0 )
>>>>> + {
>>>>> + struct p2m_domain *p2m = p2m_get_hostp2m(d);
>>>>> +
>>>>> + if ( read_atomic(&p2m->ioreq.entry_count) )
>>>>> + p2m_change_entry_type_global(d, p2m_ioreq_server, p2m_ram_rw);
>>>>> + }
>>>> If you do this after dropping the lock, don't you risk a race with
>>>> another server mapping the type to itself?
>>> I believe it's OK. Remaining p2m_ioreq_server entries still needs to be
>>> cleaned anyway.
>> Are you refusing a new server mapping the type before being
>> done with the cleanup?
>
> No. I meant even a new server is mapped, we can still sweep the p2m
> table later asynchronously.
> But this reminds me other point - will a dm op be interrupted by another
> one, or should it?
Interrupted? Two of them may run in parallel on different CPUs,
against the same target domain.
> Since we have patch 5/5 which sweep the p2m table right after the unmap
> happens, maybe
> we should refuse any mapping requirement if there's remaining
> p2m_ioreq_server entries.
That's what I've tried to hint at with my question.
Jan
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next prev parent reply other threads:[~2017-03-24 10:37 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-21 2:52 [PATCH v9 0/5] x86/ioreq server: Introduce HVMMEM_ioreq_server mem type Yu Zhang
2017-03-21 2:52 ` [PATCH v9 1/5] x86/ioreq server: Release the p2m lock after mmio is handled Yu Zhang
2017-03-29 13:39 ` George Dunlap
2017-03-29 13:50 ` Jan Beulich
2017-03-21 2:52 ` [PATCH v9 2/5] x86/ioreq server: Add DMOP to map guest ram with p2m_ioreq_server to an ioreq server Yu Zhang
2017-03-22 7:49 ` Tian, Kevin
2017-03-22 10:12 ` Yu Zhang
2017-03-24 9:26 ` Tian, Kevin
2017-03-24 12:34 ` Yu Zhang
2017-03-22 14:21 ` Jan Beulich
2017-03-23 3:23 ` Yu Zhang
2017-03-23 8:57 ` Jan Beulich
2017-03-24 9:05 ` Yu Zhang
2017-03-24 10:19 ` Jan Beulich
2017-03-24 12:35 ` Yu Zhang
2017-03-24 13:09 ` Jan Beulich
2017-03-21 2:52 ` [PATCH v9 3/5] x86/ioreq server: Handle read-modify-write cases for p2m_ioreq_server pages Yu Zhang
2017-03-22 14:22 ` Jan Beulich
2017-03-21 2:52 ` [PATCH v9 4/5] x86/ioreq server: Asynchronously reset outstanding p2m_ioreq_server entries Yu Zhang
2017-03-21 10:05 ` Paul Durrant
2017-03-22 8:10 ` Tian, Kevin
2017-03-22 10:12 ` Yu Zhang
2017-03-24 9:37 ` Tian, Kevin
2017-03-24 12:45 ` Yu Zhang
2017-03-22 14:29 ` Jan Beulich
2017-03-23 3:23 ` Yu Zhang
2017-03-23 9:00 ` Jan Beulich
2017-03-24 9:05 ` Yu Zhang
2017-03-24 10:37 ` Jan Beulich [this message]
2017-03-24 12:36 ` Yu Zhang
2017-03-21 2:52 ` [PATCH v9 5/5] x86/ioreq server: Synchronously reset outstanding p2m_ioreq_server entries when an ioreq server unmaps Yu Zhang
2017-03-21 10:00 ` Paul Durrant
2017-03-21 11:15 ` Yu Zhang
2017-03-21 13:49 ` Paul Durrant
2017-03-21 14:14 ` Yu Zhang
2017-03-22 8:28 ` Tian, Kevin
2017-03-22 8:54 ` Jan Beulich
2017-03-22 9:02 ` Tian, Kevin
2017-03-22 14:39 ` Jan Beulich
2017-03-23 3:23 ` Yu Zhang
2017-03-23 9:02 ` Jan Beulich
2017-03-24 9:05 ` Yu Zhang
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