From: Dave Hansen <dave.hansen@linux.intel.com>
To: Andy Lutomirski <luto@kernel.org>, Nadav Amit <namit@vmware.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>, Willy Tarreau <w@1wt.eu>,
Nadav Amit <nadav.amit@gmail.com>, X86 ML <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC v2 5/6] x86: Use global pages when PTI is disabled
Date: Thu, 15 Feb 2018 12:32:50 -0800 [thread overview]
Message-ID: <3f69237a-ee32-3d06-dacd-a7f7897f6251@linux.intel.com> (raw)
In-Reply-To: <CALCETrX+F5apPenXGBf9oAc+aJieQYDA81zigPk6q6q6pa_i5A@mail.gmail.com>
On 02/15/2018 11:53 AM, Andy Lutomirski wrote:
>> --- a/arch/x86/include/asm/tlbflush.h
>> +++ b/arch/x86/include/asm/tlbflush.h
>> @@ -319,6 +319,12 @@ static inline void set_cpu_pti_disable(unsigned short disable)
>> WARN_ON_ONCE(preemptible());
>>
>> pti_update_user_cs64(cpu_pti_disable(), disable);
>> + if (__supported_pte_mask & _PAGE_GLOBAL) {
>> + if (disable)
>> + cr4_set_bits(X86_CR4_PGE);
>> + else
>> + cr4_clear_bits(X86_CR4_PGE);
>> + }
> This will be *extremely* slow, and I don't see the point at all. What
> are you accomplishing here?
It won't be slow if you always run compat processes, I guess.
But mixing these in here will eat a big chunk of the benefit of having
global pages (or PCIDs for that matter) in the first place.
next prev parent reply other threads:[~2018-02-15 20:32 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-15 16:35 [PATCH RFC v2 0/6] x86: Disabling PTI in compatibility mode Nadav Amit
2018-02-15 16:35 ` [PATCH RFC v2 1/6] x86: Skip PTI when disable indication is set Nadav Amit
2018-02-15 18:10 ` Dave Hansen
2018-02-15 19:51 ` Andy Lutomirski
2018-02-15 20:51 ` Nadav Amit
2018-02-15 23:35 ` Andy Lutomirski
2018-02-15 16:35 ` [PATCH RFC v2 2/6] x86: Save pti_disable for each mm_context Nadav Amit
2018-02-15 16:35 ` [PATCH RFC v2 3/6] x86: Switching page-table isolation Nadav Amit
2018-02-15 16:36 ` [PATCH RFC v2 4/6] x86: Disable PTI on compatibility mode Nadav Amit
2018-02-15 20:02 ` Andy Lutomirski
2018-02-15 20:58 ` Nadav Amit
2018-02-15 23:29 ` Andy Lutomirski
2018-02-16 0:08 ` Linus Torvalds
2018-02-16 0:22 ` Nadav Amit
2018-02-16 0:42 ` Linus Torvalds
2018-02-16 3:03 ` Andy Lutomirski
2018-02-16 4:55 ` Nadav Amit
2018-02-16 0:35 ` Andrew Cooper
2018-02-16 15:20 ` Andy Lutomirski
2018-02-16 7:11 ` Cyrill Gorcunov
2018-02-16 22:07 ` Dmitry Safonov
2018-02-16 22:11 ` Nadav Amit
2018-02-16 16:25 ` Dmitry Safonov
2018-02-15 16:36 ` [PATCH RFC v2 5/6] x86: Use global pages when PTI is disabled Nadav Amit
2018-02-15 16:54 ` Dave Hansen
2018-02-15 17:36 ` Nadav Amit
2018-02-15 17:47 ` Nadav Amit
2018-02-15 18:08 ` Dave Hansen
2018-02-15 19:53 ` Andy Lutomirski
2018-02-15 20:32 ` Dave Hansen [this message]
2018-02-15 20:45 ` Nadav Amit
2018-02-15 16:36 ` [PATCH RFC v2 6/6] selftest: x86: test using CS64 on compatibility-mode Nadav Amit
2018-02-16 0:21 ` [PATCH RFC v2 0/6] x86: Disabling PTI in compatibility mode Dave Hansen
2018-02-16 0:25 ` Nadav Amit
2018-02-16 0:42 ` Dave Hansen
2018-02-16 0:48 ` Nadav Amit
2018-02-16 0:45 ` Andrew Cooper
2018-02-16 0:51 ` Nadav Amit
2018-02-16 1:04 ` Andrew Cooper
2018-02-16 3:05 ` Andy Lutomirski
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