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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 1/3] VMX: use a single, global APIC access page
Date: Fri, 23 Apr 2021 16:42:21 +0200	[thread overview]
Message-ID: <d4c91967-2934-5b55-4228-e8028a5c4290@suse.com> (raw)
In-Reply-To: <YILXDfXfR69mwfHH@Air-de-Roger>

On 23.04.2021 16:17, Roger Pau Monné wrote:
> On Fri, Apr 23, 2021 at 12:52:57PM +0200, Jan Beulich wrote:
>> --- a/xen/arch/x86/mm/shadow/set.c
>> +++ b/xen/arch/x86/mm/shadow/set.c
>> @@ -94,6 +94,15 @@ shadow_get_page_from_l1e(shadow_l1e_t sl
>>      ASSERT(!sh_l1e_is_magic(sl1e));
>>      ASSERT(shadow_mode_refcounts(d));
>>  
>> +    /*
>> +     * Check whether refcounting is suppressed on this page. For example,
>> +     * VMX'es APIC access MFN is just a surrogate page.  It doesn't actually
>> +     * get accessed, and hence there's no need to refcount it.
>> +     */
>> +    mfn = shadow_l1e_get_mfn(sl1e);
>> +    if ( mfn_valid(mfn) && page_refcounting_suppressed(mfn_to_page(mfn)) )
>> +        return 0;
>> +
>>      res = get_page_from_l1e(sl1e, d, d);
>>  
>>      /*
>> --- a/xen/arch/x86/mm/shadow/types.h
>> +++ b/xen/arch/x86/mm/shadow/types.h
>> @@ -276,9 +276,16 @@ int shadow_set_l4e(struct domain *d, sha
>>  static void inline
>>  shadow_put_page_from_l1e(shadow_l1e_t sl1e, struct domain *d)
>>  {
>> +    mfn_t mfn;
>> +
>>      if ( !shadow_mode_refcounts(d) )
>>          return;
>>  
>> +    if ( mfn_valid(mfn = shadow_l1e_get_mfn(sl1e)) &&
> 
> Nit: I would prefer if assigned mfn outside of the condition, like
> it's done in the chunk added to shadow_get_page_from_l1e.

Well, I did it differently here because the variable really is
only needed inside the if(), whereas in "get" the subsequent
patches use it elsewhere as well. I'll wait what Tim says.

> The rest LGTM, so:
> 
> Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

Thanks.

Jan


  reply	other threads:[~2021-04-23 14:42 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
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 [this message]
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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