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From: Nadav Amit <nadav.amit@gmail.com>
To: "Anaczkowski, Lukasz" <lukasz.anaczkowski@intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"ak@linux.intel.com" <ak@linux.intel.com>,
	"kirill.shutemov@linux.intel.com"
	<kirill.shutemov@linux.intel.com>,
	"mhocko@suse.com" <mhocko@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Srinivasappa, Harish" <harish.srinivasappa@intel.com>,
	"Odzioba, Lukasz" <lukasz.odzioba@intel.com>,
	"Andrejczuk, Grzegorz" <grzegorz.andrejczuk@intel.com>,
	"Daniluk, Lukasz" <lukasz.daniluk@intel.com>
Subject: Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak
Date: Wed, 15 Jun 2016 13:04:48 -0700	[thread overview]
Message-ID: <613007E2-2A88-4934-9364-A5A66A555305@gmail.com> (raw)
In-Reply-To: <C1C2579D7BE026428F81F41198ADB17237A8670A@irsmsx110.ger.corp.intel.com>

Lukasz <lukasz.anaczkowski@intel.com> wrote:

> From: Nadav Amit [mailto:nadav.amit@gmail.com] 
> Sent: Tuesday, June 14, 2016 8:38 PM
> 
>>> +	pte_t pte = ptep_get_and_clear(mm, addr, ptep);
>>> +
>>> +	if (boot_cpu_has_bug(X86_BUG_PTE_LEAK))
>>> +		fix_pte_leak(mm, addr, ptep);
>>> +	return pte;
>>> }
>> 
>> I missed it on the previous iteration: ptep_get_and_clear already calls 
>> fix_pte_leak when needed. So do you need to call it again here?
> 
> You're right, Nadav. Not needing this. Will be removed in next version of the patch.

Be careful here. According to the SDM when invalidating a huge-page,
each 4KB page needs to be invalidated separately. In practice, when
Linux invalidates 2MB/1GB pages it performs a full TLB flush. The
full flush may not be required on knights landing, and specifically
for the workaround, but you should check.  

Regards,
Nadav

WARNING: multiple messages have this Message-ID (diff)
From: Nadav Amit <nadav.amit@gmail.com>
To: "Anaczkowski, Lukasz" <lukasz.anaczkowski@intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"ak@linux.intel.com" <ak@linux.intel.com>,
	"kirill.shutemov@linux.intel.com"
	<kirill.shutemov@linux.intel.com>,
	"mhocko@suse.com" <mhocko@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Srinivasappa, Harish" <harish.srinivasappa@intel.com>,
	"Odzioba, Lukasz" <lukasz.odzioba@intel.com>,
	"Andrejczuk, Grzegorz" <grzegorz.andrejczuk@intel.com>,
	"Daniluk, Lukasz" <lukasz.daniluk@intel.com>
Subject: Re: [PATCH v2] Linux VM workaround for Knights Landing A/D leak
Date: Wed, 15 Jun 2016 13:04:48 -0700	[thread overview]
Message-ID: <613007E2-2A88-4934-9364-A5A66A555305@gmail.com> (raw)
In-Reply-To: <C1C2579D7BE026428F81F41198ADB17237A8670A@irsmsx110.ger.corp.intel.com>

Lukasz <lukasz.anaczkowski@intel.com> wrote:

> From: Nadav Amit [mailto:nadav.amit@gmail.com] 
> Sent: Tuesday, June 14, 2016 8:38 PM
> 
>>> +	pte_t pte = ptep_get_and_clear(mm, addr, ptep);
>>> +
>>> +	if (boot_cpu_has_bug(X86_BUG_PTE_LEAK))
>>> +		fix_pte_leak(mm, addr, ptep);
>>> +	return pte;
>>> }
>> 
>> I missed it on the previous iteration: ptep_get_and_clear already calls 
>> fix_pte_leak when needed. So do you need to call it again here?
> 
> You're right, Nadav. Not needing this. Will be removed in next version of the patch.

Be careful here. According to the SDM when invalidating a huge-page,
each 4KB page needs to be invalidated separately. In practice, when
Linux invalidates 2MB/1GB pages it performs a full TLB flush. The
full flush may not be required on knights landing, and specifically
for the workaround, but you should check.  

Regards,
Nadav
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  reply	other threads:[~2016-06-15 20:04 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-14 15:58 [PATCH] Linux VM workaround for Knights Landing A/D leak Lukasz Anaczkowski
2016-06-14 15:58 ` Lukasz Anaczkowski
2016-06-14 16:31 ` kbuild test robot
2016-06-14 16:31   ` kbuild test robot
2016-06-14 16:47 ` Nadav Amit
2016-06-14 16:47   ` Nadav Amit
2016-06-14 16:54   ` Anaczkowski, Lukasz
2016-06-14 16:54     ` Anaczkowski, Lukasz
2016-06-14 17:01   ` [PATCH v2] " Lukasz Anaczkowski
2016-06-14 17:01     ` Lukasz Anaczkowski
2016-06-14 17:24     ` Dave Hansen
2016-06-14 17:24       ` Dave Hansen
2016-06-14 18:34       ` One Thousand Gnomes
2016-06-14 18:34         ` One Thousand Gnomes
2016-06-14 18:54         ` Dave Hansen
2016-06-14 18:54           ` Dave Hansen
2016-06-14 19:19           ` Borislav Petkov
2016-06-14 19:19             ` Borislav Petkov
2016-06-14 20:20             ` H. Peter Anvin
2016-06-14 20:47               ` Borislav Petkov
2016-06-14 20:54                 ` H. Peter Anvin
2016-06-14 21:02                   ` Borislav Petkov
2016-06-14 21:08                     ` H. Peter Anvin
2016-06-14 21:13                     ` H. Peter Anvin
2016-06-14 18:10     ` Borislav Petkov
2016-06-14 18:10       ` Borislav Petkov
2016-06-15 13:12       ` Anaczkowski, Lukasz
2016-06-15 13:12         ` Anaczkowski, Lukasz
2016-06-14 18:38     ` Nadav Amit
2016-06-14 18:38       ` Nadav Amit
2016-06-15 13:12       ` Anaczkowski, Lukasz
2016-06-15 13:12         ` Anaczkowski, Lukasz
2016-06-15 20:04         ` Nadav Amit [this message]
2016-06-15 20:04           ` Nadav Amit
2016-06-15 20:10           ` Dave Hansen
2016-06-15 20:10             ` Dave Hansen
2016-06-15 20:26             ` Nadav Amit
2016-06-15 20:26               ` Nadav Amit
2016-06-16 15:14     ` [PATCH v3] " Lukasz Anaczkowski
2016-06-16 15:14       ` Lukasz Anaczkowski
2016-06-16 16:43       ` Nadav Amit
2016-06-16 16:43         ` Nadav Amit
2016-06-16 20:23       ` Dave Hansen
2016-06-16 20:23         ` Dave Hansen
2016-06-14 17:18   ` [PATCH] " Dave Hansen
2016-06-14 17:18     ` Dave Hansen
2016-06-14 20:16     ` Nadav Amit
2016-06-14 20:16       ` Nadav Amit
2016-06-14 21:37       ` Dave Hansen
2016-06-14 21:37         ` Dave Hansen
2016-06-15  2:20         ` Andy Lutomirski
2016-06-15  2:20           ` Andy Lutomirski
2016-06-15  2:35           ` Nadav Amit
2016-06-15  2:35             ` Nadav Amit
2016-06-15  2:36             ` Andy Lutomirski
2016-06-15  2:36               ` Andy Lutomirski
2016-06-15  2:44               ` Nadav Amit
2016-06-15  2:44                 ` Nadav Amit
2016-06-15  3:09                 ` Andy Lutomirski
2016-06-15  3:09                   ` Andy Lutomirski
2016-06-15  3:20         ` Nadav Amit
2016-06-15  3:20           ` Nadav Amit
2016-06-14 16:58 ` kbuild test robot
2016-06-14 16:58   ` kbuild test robot
2016-06-14 17:19 ` Dave Hansen
2016-06-14 17:19   ` Dave Hansen
2016-06-15 13:06   ` Anaczkowski, Lukasz
2016-06-15 13:06     ` Anaczkowski, Lukasz
2016-06-14 17:47 ` kbuild test robot
2016-06-14 17:47   ` kbuild test robot

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