From: Andrew Cooper <andrew.cooper3@citrix.com>
To: "Yu, Zhang" <yu.c.zhang@linux.intel.com>, xen-devel@lists.xen.org
Cc: Kevin Tian <kevin.tian@intel.com>, Keir Fraser <keir@xen.org>,
Jan Beulich <jbeulich@suse.com>,
George Dunlap <george.dunlap@eu.citrix.com>,
Tim Deegan <tim@xen.org>, Paul Durrant <paul.durrant@citrix.com>,
zhiyuan.lv@intel.com, Jun Nakajima <jun.nakajima@intel.com>
Subject: Re: [PATCH v2 3/3] x86/ioreq server: Add HVMOP to map guest ram with p2m_ioreq_server to an ioreq server
Date: Mon, 11 Apr 2016 13:20:46 +0100 [thread overview]
Message-ID: <570B969E.5030400@citrix.com> (raw)
In-Reply-To: <570B8705.3080109@linux.intel.com>
On 11/04/16 12:14, Yu, Zhang wrote:
>
>
> On 4/8/2016 9:33 PM, Andrew Cooper wrote:
>> On 31/03/16 11:53, Yu Zhang wrote:
>>> A new HVMOP - HVMOP_map_mem_type_to_ioreq_server, is added to
>>> let one ioreq server claim/disclaim its responsibility for the
>>> handling of guest pages with p2m type p2m_ioreq_server. Users
>>> of this HVMOP can specify whether the p2m_ioreq_server is supposed
>>> to handle write accesses or read ones or both in a parameter named
>>> flags. For now, we only support one ioreq server for this p2m type,
>>> so once an ioreq server has claimed its ownership, subsequent calls
>>> of the HVMOP_map_mem_type_to_ioreq_server will fail. Users can also
>>> disclaim the ownership of guest ram pages with this p2m type, by
>>> triggering this new HVMOP, with ioreq server id set to the current
>>> owner's and flags parameter set to 0.
>>>
>>> For now, both HVMOP_map_mem_type_to_ioreq_server and p2m_ioreq_server
>>> are only supported for HVMs with HAP enabled.
>>>
>>> Note that flags parameter(if not 0) of this HVMOP only indicates
>>> which kind of memory accesses are to be forwarded to an ioreq server,
>>> it has impact on the access rights of guest ram pages, but are not
>>> the same. Due to hardware limitations, if only write operations are
>>> to be forwarded, read ones will be performed at full speed, with
>>> no hypervisor intervention. But if read ones are to be forwarded to
>>> an ioreq server, writes will inevitably be trapped into hypervisor,
>>> which means significant performance impact.
>>>
>>> Also note that this HVMOP_map_mem_type_to_ioreq_server will not
>>> change the p2m type of any guest ram page, until HVMOP_set_mem_type
>>> is triggered. So normally the steps should be the backend driver
>>> first claims its ownership of guest ram pages with p2m_ioreq_server
>>> type, and then sets the memory type to p2m_ioreq_server for specified
>>> guest ram pages.
>>>
>>> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
>>> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
>>> Cc: Keir Fraser <keir@xen.org>
>>> Cc: Jan Beulich <jbeulich@suse.com>
>>> Cc: Andrew Cooper <andrew.cooper3@citrix.com>
>>> Cc: George Dunlap <george.dunlap@eu.citrix.com>
>>> Cc: Jun Nakajima <jun.nakajima@intel.com>
>>> Cc: Kevin Tian <kevin.tian@intel.com>
>>> Cc: Tim Deegan <tim@xen.org>
>>> ---
>>> xen/arch/x86/hvm/emulate.c | 125
>>> +++++++++++++++++++++++++++++++++++++--
>>> xen/arch/x86/hvm/hvm.c | 95 +++++++++++++++++++++++++++--
>>> xen/arch/x86/mm/hap/nested_hap.c | 2 +-
>>> xen/arch/x86/mm/p2m-ept.c | 14 ++++-
>>> xen/arch/x86/mm/p2m-pt.c | 25 +++++---
>>> xen/arch/x86/mm/p2m.c | 82 +++++++++++++++++++++++++
>>> xen/arch/x86/mm/shadow/multi.c | 3 +-
>>> xen/include/asm-x86/p2m.h | 36 +++++++++--
>>> xen/include/public/hvm/hvm_op.h | 37 ++++++++++++
>>> 9 files changed, 395 insertions(+), 24 deletions(-)
>>>
>>> diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
>>> index ddc8007..77a4793 100644
>>> --- a/xen/arch/x86/hvm/emulate.c
>>> +++ b/xen/arch/x86/hvm/emulate.c
>>> @@ -94,11 +94,69 @@ static const struct hvm_io_handler null_handler = {
>>> .ops = &null_ops
>>> };
>>>
>>> +static int mem_read(const struct hvm_io_handler *io_handler,
>>> + uint64_t addr,
>>> + uint32_t size,
>>> + uint64_t *data)
>>> +{
>>> + struct domain *currd = current->domain;
>>> + unsigned long gmfn = paddr_to_pfn(addr);
>>> + unsigned long offset = addr & ~PAGE_MASK;
>>> + struct page_info *page = get_page_from_gfn(currd, gmfn, NULL,
>>> P2M_UNSHARE);
>>> + uint8_t *p;
>>> +
>>> + if ( !page )
>>> + return X86EMUL_UNHANDLEABLE;
>>> +
>>> + p = __map_domain_page(page);
>>> + p += offset;
>>> + memcpy(data, p, size);
>>
>> What happens when offset + size crosses the page boundary?
>>
>
> The 'size' is set in hvmemul_linear_mmio_access(), to insure offset +
> size will not cross the page boundary.
Ok, in which case please
ASSERT(offset + size < PAGE_SIZE)
So it is absolutely clear in this function that the caller is required
to honour this restriction.
~Andrew
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next prev parent reply other threads:[~2016-04-11 12:20 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-31 10:53 [PATCH v2 0/3] x86/ioreq server: introduce HVMMEM_ioreq_server mem type Yu Zhang
2016-03-31 10:53 ` [PATCH v2 1/3] x86/ioreq server: Add new functions to get/set memory types Yu Zhang
2016-04-05 13:57 ` George Dunlap
2016-04-05 14:08 ` George Dunlap
2016-04-08 13:25 ` Andrew Cooper
2016-03-31 10:53 ` [PATCH v2 2/3] x86/ioreq server: Rename p2m_mmio_write_dm to p2m_ioreq_server Yu Zhang
2016-04-05 14:38 ` George Dunlap
2016-04-08 13:26 ` Andrew Cooper
2016-04-08 21:48 ` Jan Beulich
2016-04-18 8:41 ` Paul Durrant
2016-04-18 9:10 ` George Dunlap
2016-04-18 9:14 ` Wei Liu
2016-04-18 9:45 ` Paul Durrant
2016-04-18 16:40 ` Jan Beulich
2016-04-18 16:45 ` Paul Durrant
2016-04-18 16:47 ` Jan Beulich
2016-04-18 16:58 ` Paul Durrant
2016-04-19 11:02 ` Yu, Zhang
2016-04-19 11:15 ` Paul Durrant
2016-04-19 11:38 ` Yu, Zhang
2016-04-19 11:50 ` Paul Durrant
2016-04-19 16:51 ` Jan Beulich
2016-04-20 14:59 ` Wei Liu
2016-04-20 15:02 ` George Dunlap
2016-04-20 16:30 ` George Dunlap
2016-04-20 16:52 ` Jan Beulich
2016-04-20 16:58 ` Paul Durrant
2016-04-20 17:06 ` George Dunlap
2016-04-20 17:09 ` Paul Durrant
2016-04-21 12:24 ` Yu, Zhang
2016-04-21 13:31 ` Paul Durrant
2016-04-21 13:48 ` Yu, Zhang
2016-04-21 13:56 ` Paul Durrant
2016-04-21 14:09 ` George Dunlap
2016-04-20 17:08 ` George Dunlap
2016-04-21 12:04 ` Yu, Zhang
2016-03-31 10:53 ` [PATCH v2 3/3] x86/ioreq server: Add HVMOP to map guest ram with p2m_ioreq_server to an ioreq server Yu Zhang
[not found] ` <20160404082556.GC28633@deinos.phlegethon.org>
2016-04-05 6:01 ` Yu, Zhang
2016-04-06 17:13 ` George Dunlap
2016-04-07 7:01 ` Yu, Zhang
[not found] ` <CAFLBxZbLp2zWzCzQTaJNWbanQSmTJ57ZyTh0qaD-+YUn8o8pyQ@mail.gmail.com>
2016-04-08 10:39 ` George Dunlap
[not found] ` <5707839F.9060803@linux.intel.com>
2016-04-08 11:01 ` George Dunlap
2016-04-11 11:15 ` Yu, Zhang
2016-04-14 10:45 ` Yu, Zhang
2016-04-18 15:57 ` Paul Durrant
2016-04-19 9:11 ` Yu, Zhang
2016-04-19 9:21 ` Paul Durrant
2016-04-19 9:44 ` Yu, Zhang
2016-04-19 10:05 ` Paul Durrant
2016-04-19 11:17 ` Yu, Zhang
2016-04-19 11:47 ` Paul Durrant
2016-04-19 11:59 ` Yu, Zhang
2016-04-20 14:50 ` George Dunlap
2016-04-20 14:57 ` Paul Durrant
2016-04-20 15:37 ` George Dunlap
2016-04-20 16:30 ` Paul Durrant
2016-04-20 16:58 ` George Dunlap
2016-04-21 13:28 ` Yu, Zhang
2016-04-21 13:21 ` Yu, Zhang
2016-04-22 11:27 ` Wei Liu
2016-04-22 11:30 ` George Dunlap
2016-04-19 4:37 ` Tian, Kevin
2016-04-19 9:21 ` Yu, Zhang
2016-04-08 13:33 ` Andrew Cooper
2016-04-11 11:14 ` Yu, Zhang
2016-04-11 12:20 ` Andrew Cooper [this message]
2016-04-11 16:25 ` Jan Beulich
2016-04-08 22:28 ` Jan Beulich
2016-04-11 11:14 ` Yu, Zhang
2016-04-11 16:31 ` Jan Beulich
2016-04-12 9:37 ` Yu, Zhang
2016-04-12 15:08 ` Jan Beulich
2016-04-14 9:56 ` Yu, Zhang
2016-04-19 4:50 ` Tian, Kevin
2016-04-19 8:46 ` Paul Durrant
2016-04-19 9:27 ` Yu, Zhang
2016-04-19 9:40 ` Paul Durrant
2016-04-19 9:49 ` Yu, Zhang
2016-04-19 10:01 ` Paul Durrant
2016-04-19 9:54 ` Yu, Zhang
2016-04-19 9:15 ` Yu, Zhang
2016-04-19 9:23 ` Paul Durrant
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