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Groups > linux.kernel > #1672014
| From | Andy Lutomirski <luto@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v3 10/11] x86/mm: Enable CR4.PCIDE on supported systems |
| Date | 2017-06-21 22:40 +0200 |
| Message-ID | <tUUzU-2OU-13@gated-at.bofh.it> (permalink) |
| References | <tUGnf-1Tn-3@gated-at.bofh.it> <tUGnh-1Tn-41@gated-at.bofh.it> <tUKhd-4ly-43@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Wed, Jun 21, 2017 at 2:39 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Tue, 20 Jun 2017, Andy Lutomirski wrote:
>> + /* Set up PCID */
>> + if (cpu_has(c, X86_FEATURE_PCID)) {
>> + if (cpu_has(c, X86_FEATURE_PGE)) {
>> + cr4_set_bits(X86_CR4_PCIDE);
>
> So I assume that you made sure that the PCID bits in CR3 are zero under all
> circumstances as setting PCIDE would cause a #GP if not.
Yes. All existing code just shoves a PA of a page table in there. As
far as I know, neither Linux nor anyone else uses the silly PCD and
PWT bits. It's not even clear to me that they are functional if PAT
is enabled.
>
> And what happens on kexec etc? We need to reset the asid and PCIDE I assume.
>
I assume it works roughly the same way as suspend, etc --
mmu_cr4_features has the desired CR4 and the init code deals with it.
And PGE, PKE, etc all work correctly. I'm not sure why PCIDE needs to
be cleared -- the init code will work just fine even if PCIDE is
unexpectedly set.
That being said, I haven't managed to understand what exactly the
kexec code is doing. But I think the relevant bit is here in
relocate_kernel_64.S:
/*
* Set cr4 to a known state:
* - physical address extension enabled
*/
movl $X86_CR4_PAE, %eax
movq %rax, %cr4
Kexec folks, is it safe to assume that kexec can already deal with the
new and old kernels disagreeing on what CR4 should be?
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[PATCH v3 00/11] PCID and improved laziness Andy Lutomirski <luto@kernel.org> - 2017-06-21 07:30 +0200
[PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Andy Lutomirski <luto@kernel.org> - 2017-06-21 07:30 +0200
Re: [PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Thomas Gleixner <tglx@linutronix.de> - 2017-06-21 15:40 +0200
Re: [PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Thomas Gleixner <tglx@linutronix.de> - 2017-06-21 15:50 +0200
Re: [PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Andy Lutomirski <luto@kernel.org> - 2017-06-22 05:00 +0200
Re: [PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Thomas Gleixner <tglx@linutronix.de> - 2017-06-22 14:30 +0200
Re: [PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Andy Lutomirski <luto@kernel.org> - 2017-06-22 20:20 +0200
Re: [PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Thomas Gleixner <tglx@linutronix.de> - 2017-06-22 23:30 +0200
Re: [PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Andy Lutomirski <luto@kernel.org> - 2017-06-23 05:10 +0200
Re: [PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Thomas Gleixner <tglx@linutronix.de> - 2017-06-23 09:30 +0200
Re: [PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Nadav Amit <nadav.amit@gmail.com> - 2017-06-22 18:20 +0200
Re: [PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Andy Lutomirski <luto@kernel.org> - 2017-06-22 20:20 +0200
Re: [PATCH v3 11/11] x86/mm: Try to preserve old TLB entries using PCID Borislav Petkov <bp@alien8.de> - 2017-06-26 18:10 +0200
[PATCH v3 08/11] x86/mm: Disable PCID on 32-bit kernels Andy Lutomirski <luto@kernel.org> - 2017-06-21 07:30 +0200
Re: [PATCH v3 08/11] x86/mm: Disable PCID on 32-bit kernels Thomas Gleixner <tglx@linutronix.de> - 2017-06-21 11:30 +0200
Re: [PATCH v3 08/11] x86/mm: Disable PCID on 32-bit kernels Borislav Petkov <bp@alien8.de> - 2017-06-23 11:30 +0200
[PATCH v3 02/11] x86/ldt: Simplify LDT switching logic Andy Lutomirski <luto@kernel.org> - 2017-06-21 07:30 +0200
Re: [PATCH v3 02/11] x86/ldt: Simplify LDT switching logic Thomas Gleixner <tglx@linutronix.de> - 2017-06-21 10:10 +0200
Re: [PATCH v3 02/11] x86/ldt: Simplify LDT switching logic Borislav Petkov <bp@alien8.de> - 2017-06-21 11:50 +0200
[tip:x86/mm] x86/ldt: Simplify the LDT switching logic tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2017-06-22 13:20 +0200
[PATCH v3 01/11] x86/mm: Don't reenter flush_tlb_func_common() Andy Lutomirski <luto@kernel.org> - 2017-06-21 07:30 +0200
Re: [PATCH v3 01/11] x86/mm: Don't reenter flush_tlb_func_common() Thomas Gleixner <tglx@linutronix.de> - 2017-06-21 10:10 +0200
Re: [PATCH v3 01/11] x86/mm: Don't reenter flush_tlb_func_common() Borislav Petkov <bp@alien8.de> - 2017-06-21 10:50 +0200
Re: [PATCH v3 01/11] x86/mm: Don't reenter flush_tlb_func_common() Andy Lutomirski <luto@kernel.org> - 2017-06-21 17:20 +0200
Re: [PATCH v3 01/11] x86/mm: Don't reenter flush_tlb_func_common() Nadav Amit <nadav.amit@gmail.com> - 2017-06-22 01:30 +0200
Re: [PATCH v3 01/11] x86/mm: Don't reenter flush_tlb_func_common() Andy Lutomirski <luto@kernel.org> - 2017-06-22 04:30 +0200
Re: [PATCH v3 01/11] x86/mm: Don't reenter flush_tlb_func_common() Ingo Molnar <mingo@kernel.org> - 2017-06-22 09:40 +0200
[PATCH v3 06/11] x86/mm: Rework lazy TLB mode and TLB freshness tracking Andy Lutomirski <luto@kernel.org> - 2017-06-21 07:30 +0200
Re: [PATCH v3 06/11] x86/mm: Rework lazy TLB mode and TLB freshness tracking Thomas Gleixner <tglx@linutronix.de> - 2017-06-21 11:10 +0200
Re: [PATCH v3 06/11] x86/mm: Rework lazy TLB mode and TLB freshness tracking Andy Lutomirski <luto@kernel.org> - 2017-06-21 18:30 +0200
Re: [PATCH v3 06/11] x86/mm: Rework lazy TLB mode and TLB freshness tracking Borislav Petkov <bp@alien8.de> - 2017-06-21 19:30 +0200
Re: [PATCH v3 06/11] x86/mm: Rework lazy TLB mode and TLB freshness tracking Borislav Petkov <bp@alien8.de> - 2017-06-22 17:00 +0200
Re: [PATCH v3 06/11] x86/mm: Rework lazy TLB mode and TLB freshness tracking Andy Lutomirski <luto@kernel.org> - 2017-06-22 19:50 +0200
Re: [PATCH v3 06/11] x86/mm: Rework lazy TLB mode and TLB freshness tracking Borislav Petkov <bp@alien8.de> - 2017-06-22 21:10 +0200
Re: [PATCH v3 06/11] x86/mm: Rework lazy TLB mode and TLB freshness tracking Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-06-23 15:40 +0200
Re: [PATCH v3 06/11] x86/mm: Rework lazy TLB mode and TLB freshness tracking Andy Lutomirski <luto@kernel.org> - 2017-06-23 17:30 +0200
[PATCH v3 04/11] x86/mm: Give each mm TLB flush generation a unique ID Andy Lutomirski <luto@kernel.org> - 2017-06-21 07:30 +0200
Re: [PATCH v3 04/11] x86/mm: Give each mm TLB flush generation a unique ID Thomas Gleixner <tglx@linutronix.de> - 2017-06-21 10:10 +0200
Re: [PATCH v3 04/11] x86/mm: Give each mm TLB flush generation a unique ID Borislav Petkov <bp@alien8.de> - 2017-06-21 12:40 +0200
Re: [PATCH v3 04/11] x86/mm: Give each mm TLB flush generation a unique ID Andy Lutomirski <luto@kernel.org> - 2017-06-21 18:40 +0200
Re: [PATCH v3 04/11] x86/mm: Give each mm TLB flush generation a unique ID Borislav Petkov <bp@alien8.de> - 2017-06-21 19:10 +0200
Re: [PATCH v3 04/11] x86/mm: Give each mm TLB flush generation a unique ID Borislav Petkov <bp@alien8.de> - 2017-06-21 19:50 +0200
Re: [PATCH v3 04/11] x86/mm: Give each mm TLB flush generation a unique ID Andy Lutomirski <luto@kernel.org> - 2017-06-22 04:40 +0200
[PATCH v3 10/11] x86/mm: Enable CR4.PCIDE on supported systems Andy Lutomirski <luto@kernel.org> - 2017-06-21 07:30 +0200
Re: [PATCH v3 10/11] x86/mm: Enable CR4.PCIDE on supported systems Thomas Gleixner <tglx@linutronix.de> - 2017-06-21 11:40 +0200
Re: [PATCH v3 10/11] x86/mm: Enable CR4.PCIDE on supported systems Thomas Gleixner <tglx@linutronix.de> - 2017-06-21 15:50 +0200
Re: [PATCH v3 10/11] x86/mm: Enable CR4.PCIDE on supported systems Andy Lutomirski <luto@kernel.org> - 2017-06-21 22:40 +0200
Re: [PATCH v3 10/11] x86/mm: Enable CR4.PCIDE on supported systems Borislav Petkov <bp@alien8.de> - 2017-06-23 14:00 +0200
Re: [PATCH v3 10/11] x86/mm: Enable CR4.PCIDE on supported systems Andy Lutomirski <luto@kernel.org> - 2017-06-23 17:30 +0200
Re: [PATCH v3 10/11] x86/mm: Enable CR4.PCIDE on supported systems Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-06-23 15:40 +0200
[PATCH v3 07/11] x86/mm: Stop calling leave_mm() in idle code Andy Lutomirski <luto@kernel.org> - 2017-06-21 07:30 +0200
Re: [PATCH v3 07/11] x86/mm: Stop calling leave_mm() in idle code Thomas Gleixner <tglx@linutronix.de> - 2017-06-21 11:30 +0200
Re: [PATCH v3 07/11] x86/mm: Stop calling leave_mm() in idle code Andy Lutomirski <luto@kernel.org> - 2017-06-21 18:30 +0200
Re: [PATCH v3 07/11] x86/mm: Stop calling leave_mm() in idle code Borislav Petkov <bp@alien8.de> - 2017-06-23 11:10 +0200
Re: [PATCH v3 00/11] PCID and improved laziness Linus Torvalds <torvalds@linux-foundation.org> - 2017-06-21 20:30 +0200
Re: [PATCH v3 00/11] PCID and improved laziness Andy Lutomirski <luto@kernel.org> - 2017-06-22 07:30 +0200
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