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Groups > linux.kernel > #1533551 > unrolled thread
| Started by | Andy Lutomirski <luto@kernel.org> |
|---|---|
| First post | 2016-11-30 21:40 +0100 |
| Last post | 2016-12-02 01:40 +0100 |
| Articles | 6 on this page of 46 — 8 participants |
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[PATCH 0/4] CPUID-less CPU fixes and improvements Andy Lutomirski <luto@kernel.org> - 2016-11-30 21:40 +0100
[PATCH 4/4] x86/asm: Change sync_core() to use MOV to CR2 to serialize Andy Lutomirski <luto@kernel.org> - 2016-11-30 21:40 +0100
Re: [PATCH 4/4] x86/asm: Change sync_core() to use MOV to CR2 to serialize Borislav Petkov <bp@alien8.de> - 2016-12-01 10:30 +0100
Re: [PATCH 4/4] x86/asm: Change sync_core() to use MOV to CR2 to serialize Andy Lutomirski <luto@amacapital.net> - 2016-12-01 18:10 +0100
Re: [PATCH 4/4] x86/asm: Change sync_core() to use MOV to CR2 to serialize Andrew Cooper <andrew.cooper3@citrix.com> - 2016-12-01 18:50 +0100
Re: [PATCH 4/4] x86/asm: Change sync_core() to use MOV to CR2 to serialize Ingo Molnar <mingo@kernel.org> - 2016-12-02 08:40 +0100
[PATCH 3/4] x86/microcode/intel: Replace sync_core() with cpuid_eax(1) Andy Lutomirski <luto@kernel.org> - 2016-11-30 21:40 +0100
Re: [PATCH 3/4] x86/microcode/intel: Replace sync_core() with cpuid_eax(1) Borislav Petkov <bp@alien8.de> - 2016-12-01 10:20 +0100
[PATCH v2 6/6] x86/asm: Change sync_core() to use MOV to CR2 to serialize Andy Lutomirski <luto@kernel.org> - 2016-12-02 01:40 +0100
[PATCH v2 4/6] x86/paravirt: Make sync_core() be a paravirt op Andy Lutomirski <luto@kernel.org> - 2016-12-02 01:40 +0100
[PATCH v2 3/6] x86/microcode/intel: Replace sync_core() with cpuid_eax(1) Andy Lutomirski <luto@kernel.org> - 2016-12-02 01:40 +0100
[PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andy Lutomirski <luto@kernel.org> - 2016-12-02 01:40 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andrew Cooper <andrew.cooper3@citrix.com> - 2016-12-02 12:50 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andy Lutomirski <luto@amacapital.net> - 2016-12-02 18:10 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andrew Cooper <andrew.cooper3@citrix.com> - 2016-12-02 18:20 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andrew Cooper <andrew.cooper3@citrix.com> - 2016-12-02 18:30 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andy Lutomirski <luto@amacapital.net> - 2016-12-02 18:30 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-12-02 19:50 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andy Lutomirski <luto@amacapital.net> - 2016-12-02 20:40 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2016-12-02 21:10 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-02 18:40 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andy Lutomirski <luto@kernel.org> - 2016-12-02 18:40 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Borislav Petkov <bp@kernel.org> - 2016-12-02 19:20 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-02 19:30 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Borislav Petkov <bp@kernel.org> - 2016-12-02 20:00 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-02 20:10 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-02 20:30 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Borislav Petkov <bp@alien8.de> - 2016-12-02 20:30 +0100
[PATCH] x86/alternatives: Do not use sync_core() to serialize I$ Borislav Petkov <bp@alien8.de> - 2016-12-03 16:10 +0100
Re: [PATCH] x86/alternatives: Do not use sync_core() to serialize I$ Andy Lutomirski <luto@amacapital.net> - 2016-12-03 18:20 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-02 20:40 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andy Lutomirski <luto@amacapital.net> - 2016-12-02 21:50 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-02 22:20 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andy Lutomirski <luto@amacapital.net> - 2016-12-03 00:00 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-03 00:20 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andy Lutomirski <luto@amacapital.net> - 2016-12-02 20:40 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Andy Lutomirski <luto@amacapital.net> - 2016-12-02 20:30 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Borislav Petkov <bp@alien8.de> - 2016-12-02 20:40 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Borislav Petkov <bp@alien8.de> - 2016-12-02 20:30 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-02 19:20 +0100
Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation Borislav Petkov <bp@alien8.de> - 2016-12-03 13:50 +0100
[PATCH v2 2/6] Revert "x86/boot: Fail the boot if !M486 and CPUID is missing" Andy Lutomirski <luto@kernel.org> - 2016-12-02 01:40 +0100
Re: [PATCH 0/4] CPUID-less CPU fixes and improvements Andy Lutomirski <luto@amacapital.net> - 2016-12-02 01:40 +0100
Re: [PATCH 0/4] CPUID-less CPU fixes and improvements Ingo Molnar <mingo@kernel.org> - 2016-12-02 11:20 +0100
[PATCH v2 0/6] CPUID-less CPU/sync_core fixes and improvements Andy Lutomirski <luto@kernel.org> - 2016-12-02 01:40 +0100
[PATCH v2 1/6] x86/asm/32: Make sync_core() handle missing CPUID on all 32-bit kernels Andy Lutomirski <luto@kernel.org> - 2016-12-02 01:40 +0100
Page 3 of 3 — ← Prev page 1 2 [3]
| From | Borislav Petkov <bp@alien8.de> |
|---|---|
| Date | 2016-12-03 13:50 +0100 |
| Subject | Re: [PATCH v2 5/6] x86/xen: Add a Xen-specific sync_core() implementation |
| Message-ID | <sKhVo-1bT-13@gated-at.bofh.it> |
| In reply to | #1535100 |
On Fri, Dec 02, 2016 at 09:38:38AM -0800, Andy Lutomirski wrote:
> TBH, I didn't start down this path for performance. I did it because
> I wanted to kill off a CPUID that was breaking on old CPUs that don't
> have CPUID. So I propose MOV-to-CR2 followed by an unconditional
> jump. My goal here is to make the #*!& thing work reliably and not be
> ludicrously slow. Borislav and I mulled over using an alternative to
> use CPUID if and only if we have CPUID, but that doesn't work because
> we call sync_core() before we're done applying alternatives.
Btw if the noinline thing which Linus suggested, works out, we can still
do the alternatives thing with CPUID in sync_core() because we won't
need it in alternatives.c itself anymore.
Just putting it on the table, I know you complained about the mess
yesterday on IRC and in case the CR2 move looks painful on xen, we can
still do what we initially considered. I.e., that thing:
+ /* Do a CPUID if available, otherwise do a forward jump. */
+ alternative_io("jmp 1f\n\t1:", "cpuid",
+ X86_FEATURE_CPUID,
+ "=a" (tmp),
+ "0" (1)
+ : "ebx", "ecx", "edx", "memory");
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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| From | Andy Lutomirski <luto@kernel.org> |
|---|---|
| Date | 2016-12-02 01:40 +0100 |
| Subject | [PATCH v2 2/6] Revert "x86/boot: Fail the boot if !M486 and CPUID is missing" |
| Message-ID | <sJK3o-4BW-29@gated-at.bofh.it> |
| In reply to | #1533551 |
This reverts commit ed68d7e9b9cfb64f3045ffbcb108df03c09a0f98.
The patch wasn't quite correct -- there are non-Intel (and hence
non-486) CPUs that we support that don't have CPUID. Since we no
longer require CPUID for sync_core(), just revert the patch.
I think the relevant CPUs are Geode and Elan, but I'm not sure.
In principle, we should try to do better at identifying CPUID-less
CPUs in early boot, but that's more complicated.
Reported-by: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Matthew Whitehead <tedheadster@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/boot/cpu.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/arch/x86/boot/cpu.c b/arch/x86/boot/cpu.c
index 4224ede43b4e..26240dde081e 100644
--- a/arch/x86/boot/cpu.c
+++ b/arch/x86/boot/cpu.c
@@ -87,12 +87,6 @@ int validate_cpu(void)
return -1;
}
- if (CONFIG_X86_MINIMUM_CPU_FAMILY <= 4 && !IS_ENABLED(CONFIG_M486) &&
- !has_eflag(X86_EFLAGS_ID)) {
- printf("This kernel requires a CPU with the CPUID instruction. Build with CONFIG_M486=y to run on this CPU.\n");
- return -1;
- }
-
if (err_flags) {
puts("This kernel requires the following features "
"not present on the CPU:\n");
--
2.9.3
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| From | Andy Lutomirski <luto@amacapital.net> |
|---|---|
| Date | 2016-12-02 01:40 +0100 |
| Message-ID | <sJK3o-4BW-31@gated-at.bofh.it> |
| In reply to | #1533551 |
Ugh, please ignore the accidental re-send of v1. I suck at using git. v2 is what I meant to send, but I accidentally sent both versions. :-( --Andy
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| From | Ingo Molnar <mingo@kernel.org> |
|---|---|
| Date | 2016-12-02 11:20 +0100 |
| Message-ID | <sJT6F-2yH-11@gated-at.bofh.it> |
| In reply to | #1534596 |
* Andy Lutomirski <luto@amacapital.net> wrote: > Ugh, please ignore the accidental re-send of v1. I suck at using git. > v2 is what I meant to send, but I accidentally sent both versions. :-( Would be nice to get an Ack from the Xen bits - can pick -v2 up after that. Thanks, Ingo
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| From | Andy Lutomirski <luto@kernel.org> |
|---|---|
| Date | 2016-12-02 01:40 +0100 |
| Subject | [PATCH v2 0/6] CPUID-less CPU/sync_core fixes and improvements |
| Message-ID | <sJK3o-4BW-19@gated-at.bofh.it> |
| In reply to | #1533551 |
*** PATCHES 1 and 2 MAY BE 4.9 MATERIAL ***
Alan Cox pointed out that the 486 isn't the only supported CPU that
doesn't have CPUID. Let's clean up the mess and make everything
faster while we're at it.
Patch 1 is intended to be an easy fix: it makes sync_core() work
without CPUID on all 32-bit kernels. It should be quite safe. This
will have a negligible performance cost during boot on kernels built
for newer CPUs. With this in place, patch 2 reverts the buggy 486
check I added.
Patches 3-6 are meant to improve the situation. Patch 3 cleans
up the Intel microcode loader and the rest (which depend on patch 3)
stops using CPUID in sync_core() altogether.
Changes from v1:
- Fix Xen
- Add timing info to the changelog (hint: 2x speedup)
- Document patch 1 a bit better.
Andy Lutomirski (6):
x86/asm/32: Make sync_core() handle missing CPUID on all 32-bit
kernels
Revert "x86/boot: Fail the boot if !M486 and CPUID is missing"
x86/microcode/intel: Replace sync_core() with cpuid_eax(1)
x86/paravirt: Make sync_core() be a paravirt op
x86/xen: Add a Xen-specific sync_core() implementation
x86/asm: Change sync_core() to use MOV to CR2 to serialize
arch/x86/boot/cpu.c | 6 ------
arch/x86/include/asm/paravirt.h | 5 +++++
arch/x86/include/asm/paravirt_types.h | 2 ++
arch/x86/include/asm/processor.h | 34 ++++++++++------------------------
arch/x86/kernel/cpu/microcode/intel.c | 6 +++---
arch/x86/kernel/paravirt.c | 2 ++
arch/x86/xen/enlighten.c | 35 +++++++++++++++++++++++++++++++++++
7 files changed, 57 insertions(+), 33 deletions(-)
--
2.9.3
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| From | Andy Lutomirski <luto@kernel.org> |
|---|---|
| Date | 2016-12-02 01:40 +0100 |
| Subject | [PATCH v2 1/6] x86/asm/32: Make sync_core() handle missing CPUID on all 32-bit kernels |
| Message-ID | <sJK3n-4BW-13@gated-at.bofh.it> |
| In reply to | #1533551 |
We support various non-Intel CPUs that don't have the CPUID
instruction, so the M486 test was wrong. For now, fix it with a big
hammer: handle missing CPUID on all 32-bit CPUs.
Reported-by: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
arch/x86/include/asm/processor.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 984a7bf17f6a..64fbc937d586 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -595,7 +595,7 @@ static inline void sync_core(void)
{
int tmp;
-#ifdef CONFIG_M486
+#ifdef CONFIG_X86_32
/*
* Do a CPUID if available, otherwise do a jump. The jump
* can conveniently enough be the jump around CPUID.
--
2.9.3
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