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: Wed, 22 Mar 2017 08:29:28 -0600 [thread overview]
Message-ID: <58D2985802000078001464CC@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1490064773-26751-5-git-send-email-yu.c.zhang@linux.intel.com>
>>> 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?
> --- a/xen/arch/x86/mm/p2m-ept.c
> +++ b/xen/arch/x86/mm/p2m-ept.c
> @@ -544,6 +544,12 @@ static int resolve_misconfig(struct p2m_domain *p2m,
> unsigned long gfn)
> e.ipat = ipat;
> if ( e.recalc && p2m_is_changeable(e.sa_p2mt) )
> {
> + if ( e.sa_p2mt == p2m_ioreq_server )
> + {
> + p2m->ioreq.entry_count--;
> + ASSERT(p2m->ioreq.entry_count >= 0);
If you did the ASSERT() first (using > 0), you wouldn't need the
type be a signed one, doubling the valid value range (even if
right now the full 64 bits can't be used anyway, but it would be
one less thing to worry about once we get 6-level page tables).
Jan
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next prev parent reply other threads:[~2017-03-22 14:29 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 [this message]
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
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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