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From: Jan Beulich <jbeulich@suse.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	Andrew Cooper <andrew.cooper3@citrix.com>, Wei Liu <wl@xen.org>,
	George Dunlap <george.dunlap@citrix.com>,
	Kevin Tian <kevin.tian@intel.com>,
	Jun Nakajima <jun.nakajima@intel.com>, Tim Deegan <tim@xen.org>
Subject: Re: [PATCH v4] VMX: use a single, global APIC access page
Date: Tue, 13 Apr 2021 14:03:52 +0200	[thread overview]
Message-ID: <4190da5f-65c2-dfee-e84e-9d5560dabf69@suse.com> (raw)
In-Reply-To: <YHVv/wyD6BphWaU/@Air-de-Roger>

On 13.04.2021 12:18, Roger Pau Monné wrote:
> On Tue, Apr 13, 2021 at 11:24:09AM +0200, Jan Beulich wrote:
>> On 12.04.2021 17:31, Roger Pau Monné wrote:
>>> On Mon, Apr 12, 2021 at 12:40:48PM +0200, Jan Beulich wrote:
>>>> +    {
>>>> +        const struct page_info *pg = mfn_to_page(mfn);
>>>> +
>>>> +        if ( !page_get_owner(pg) && (pg->count_info & PGC_extra) )
>>>> +        {
>>>> +            ASSERT(type == p2m_mmio_direct);
>>>> +            return 0;
>>>
>>> Are there any other pages that could pass this check? I don't think
>>> so, but wanted to assert.
>>
>> "Normal" extra pages have an owner, so no, there aren't any others.
>> If and when any appear, this may need further customizing, albeit
>> generally I'd hope further pages matching this pattern would also
>> want similar treatment.
> 
> I wonder whether we want to add an assert here to make sure only the
> APIC access page receives this special handling by the shadow code,
> but maybe that's a bit too much?

I think so, yes: It would require either a separate function or
making the variable global. Both feel like a layering violation.

Jan


  reply	other threads:[~2021-04-13 12:04 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-22 10:55 [PATCH v3 0/2] VMX: apic access page handling adjustments Jan Beulich
2021-02-22 10:56 ` [PATCH v3 1/2][4.15] VMX: delay p2m insertion of APIC access page Jan Beulich
2021-02-22 11:25   ` Ian Jackson
2021-02-22 14:05     ` Jan Beulich
2021-02-22 17:17       ` Ian Jackson
2021-02-22 12:15   ` Roger Pau Monné
2021-02-25  8:44   ` Jan Beulich
2021-02-26  7:06     ` Tian, Kevin
2021-02-22 10:57 ` [PATCH v3 2/2] VMX: use a single, global " Jan Beulich
2021-03-01  2:34   ` Tian, Kevin
2021-03-01  8:18     ` Jan Beulich
2021-04-12 10:40 ` [PATCH v4] " Jan Beulich
2021-04-12 15:31   ` Roger Pau Monné
2021-04-13  9:24     ` Jan Beulich
2021-04-13 10:18       ` Roger Pau Monné
2021-04-13 12:03         ` Jan Beulich [this message]
2021-04-13 13:03           ` Roger Pau Monné
2021-04-17 19:24   ` Tim Deegan
2021-04-19 11:25     ` Jan Beulich
2021-04-22  7:42       ` Tim Deegan
2021-04-22  9:38         ` Jan Beulich
2021-04-22 15:05           ` Tim Deegan
2021-04-23 10:51 ` [PATCH v4 0/3] VMX APIC access page and shadow adjustments Jan Beulich
2021-04-23 10:52   ` [PATCH v4 1/3] VMX: use a single, global APIC access page Jan Beulich
2021-04-23 14:17     ` Roger Pau Monné
2021-04-23 14:42       ` Jan Beulich
2021-04-26 17:55         ` Tim Deegan
2021-04-25  1:27     ` Tian, Kevin
2021-04-26 17:53     ` Tim Deegan
2021-04-23 10:53   ` [PATCH v4 2/3] x86/shadow: re-use variables in shadow_get_page_from_l1e() Jan Beulich
2021-04-23 10:54   ` [PATCH v4 3/3] x86/shadow: streamline shadow_get_page_from_l1e() Jan Beulich
2021-04-23 11:00   ` Really v5 (was: [PATCH v4 0/3] VMX APIC access page and shadow adjustments) Jan Beulich

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