From: Yu Zhang <yu.c.zhang@linux.intel.com>
To: Jan Beulich <JBeulich@suse.com>, Paul Durrant <paul.durrant@citrix.com>
Cc: Kevin Tian <kevin.tian@intel.com>,
George Dunlap <george.dunlap@eu.citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Tim Deegan <tim@xen.org>,
xen-devel@lists.xen.org, zhiyuan.lv@intel.com,
Jun Nakajima <jun.nakajima@intel.com>
Subject: Re: [PATCH v5 3/4] x86/ioreq server: Add HVMOP to map guest ram with p2m_ioreq_server to an ioreq server.
Date: Wed, 10 Aug 2016 16:09:44 +0800 [thread overview]
Message-ID: <57AAE148.1000401@linux.intel.com> (raw)
In-Reply-To: <57A8C4270200007800103E80@prv-mh.provo.novell.com>
On 8/8/2016 11:40 PM, Jan Beulich wrote:
>>>> On 12.07.16 at 11:02, <yu.c.zhang@linux.intel.com> wrote:
>> @@ -178,8 +179,34 @@ static int hvmemul_do_io(
>> break;
>> case X86EMUL_UNHANDLEABLE:
>> {
>> - struct hvm_ioreq_server *s =
>> - hvm_select_ioreq_server(curr->domain, &p);
>> + struct hvm_ioreq_server *s;
>> +
>> + if ( is_mmio )
>> + {
>> + unsigned long gmfn = paddr_to_pfn(addr);
>> + p2m_type_t p2mt;
>> +
>> + (void) get_gfn_query_unlocked(currd, gmfn, &p2mt);
>> +
>> + if ( p2mt == p2m_ioreq_server )
>> + {
>> + unsigned int flags;
>> +
>> + if ( dir != IOREQ_WRITE )
>> + s = NULL;
>> + else
>> + {
>> + s = p2m_get_ioreq_server(currd, &flags);
>> +
>> + if ( !(flags & P2M_IOREQ_HANDLE_WRITE_ACCESS) )
>> + s = NULL;
>> + }
>> + }
>> + else
>> + s = hvm_select_ioreq_server(currd, &p);
>> + }
>> + else
>> + s = hvm_select_ioreq_server(currd, &p);
> Wouldn't it both be more natural and make the logic even easier
> to follow if s got set to NULL up front, all the "else"-s dropped,
> and a simple
>
> if ( !s )
> s = hvm_select_ioreq_server(currd, &p);
>
> be done in the end?
>
Sorry, Jan. I tried to simplify above code, but found the new code is
still not very
clean, because in some cases the s is supposed to return NULL instead
of to be
set from the hvm_select_ioreq_server().
To keep the same logic, the simplified code looks like this:
case X86EMUL_UNHANDLEABLE:
{
- struct hvm_ioreq_server *s =
- hvm_select_ioreq_server(curr->domain, &p);
+ struct hvm_ioreq_server *s = NULL;
+ p2m_type_t p2mt = p2m_invalid;
+
+ if ( is_mmio && dir == IOREQ_WRITE )
+ {
+ unsigned long gmfn = paddr_to_pfn(addr);
+
+ (void) get_gfn_query_unlocked(currd, gmfn, &p2mt);
+
+ if ( p2mt == p2m_ioreq_server )
+ {
+ unsigned int flags;
+
+ s = p2m_get_ioreq_server(currd, &flags);
+ if ( !(flags & XEN_HVMOP_IOREQ_MEM_ACCESS_WRITE) )
+ s = NULL;
+ }
+ }
+
+ if ( !s && p2mt != p2m_ioreq_server )
+ s = hvm_select_ioreq_server(currd, &p);
/* If there is no suitable backing DM, just ignore accesses */
if ( !s )
As you can see, definition of p2mt is moved outside the if ( is_mmio )
judgement,
and is checked against p2m_ioreq_server before we search the ioreq
server's rangeset
in hvm_select_ioreq_server(). So I am not quite satisfied with this
simplification.
Any suggestions?
[snip]
Yu
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next prev parent reply other threads:[~2016-08-10 8:09 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-12 9:02 [PATCH v5 0/4] x86/ioreq server: Introduce HVMMEM_ioreq_server mem type Yu Zhang
2016-07-12 9:02 ` [PATCH v5 1/4] x86/ioreq server: Rename p2m_mmio_write_dm to p2m_ioreq_server Yu Zhang
2016-07-12 9:02 ` [PATCH v5 2/4] x86/ioreq server: Add new functions to get/set memory types Yu Zhang
2016-07-12 9:02 ` [PATCH v5 3/4] x86/ioreq server: Add HVMOP to map guest ram with p2m_ioreq_server to an ioreq server Yu Zhang
2016-08-08 15:40 ` Jan Beulich
2016-08-09 7:39 ` Yu Zhang
2016-08-09 8:11 ` Jan Beulich
2016-08-09 8:20 ` Paul Durrant
2016-08-09 8:51 ` Yu Zhang
2016-08-09 9:07 ` Paul Durrant
2016-08-10 8:09 ` Yu Zhang [this message]
2016-08-10 10:33 ` Jan Beulich
2016-08-10 10:43 ` Paul Durrant
2016-08-10 12:32 ` Yu Zhang
2016-08-10 10:43 ` Yu Zhang
2016-08-11 8:47 ` Yu Zhang
2016-08-11 8:58 ` Jan Beulich
2016-08-11 9:19 ` Yu Zhang
2016-07-12 9:02 ` [PATCH v5 4/4] x86/ioreq server: Reset outstanding p2m_ioreq_server entries when an ioreq server unmaps Yu Zhang
2016-08-08 16:29 ` Jan Beulich
2016-08-09 7:39 ` Yu Zhang
2016-08-09 8:13 ` Jan Beulich
2016-08-09 9:25 ` Yu Zhang
2016-08-09 9:45 ` Jan Beulich
2016-08-09 10:21 ` Yu Zhang
2016-08-16 13:35 ` George Dunlap
2016-08-16 13:54 ` Jan Beulich
2016-08-30 12:17 ` Yu Zhang
2016-09-02 11:00 ` Yu Zhang
2016-08-05 2:44 ` [PATCH v5 0/4] x86/ioreq server: Introduce HVMMEM_ioreq_server mem type Yu Zhang
2016-08-05 6:16 ` Jan Beulich
2016-08-05 12:46 ` George Dunlap
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