From: Borislav Petkov <bp@alien8.de>
To: Segher Boessenkool <segher@kernel.crashing.org>
Cc: shuo.a.liu@intel.com, linux-kernel@vger.kernel.org,
x86@kernel.org, Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"H . Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Yu Wang <yu1.wang@intel.com>,
Reinette Chatre <reinette.chatre@intel.com>,
Yakui Zhao <yakui.zhao@intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Fengwei Yin <fengwei.yin@intel.com>,
Zhi Wang <zhi.a.wang@intel.com>,
Zhenyu Wang <zhenyuw@linux.intel.com>,
Arvind Sankar <nivedita@alum.mit.edu>,
Peter Zijlstra <peterz@infradead.org>,
Nick Desaulniers <ndesaulniers@google.com>
Subject: Re: [PATCH v5 04/17] x86/acrn: Introduce hypercall interfaces
Date: Mon, 2 Nov 2020 19:34:30 +0100 [thread overview]
Message-ID: <20201102183430.GG15392@zn.tnic> (raw)
In-Reply-To: <20201102181000.GX2672@gate.crashing.org>
On Mon, Nov 02, 2020 at 12:10:00PM -0600, Segher Boessenkool wrote:
> movl works for moving anything g->r.
Right.
> This is not true for most insns, and not for most architectures at
> all (usually loading from memory has a separate mnemonic; moving an
> immediate number often as well (and it does not usually allow *every*
> immediate anyway, not even all numbers!)
So I've heard from other architectures. Every arch has its own problems.
:-)
> Most people do not read the documentation, they just copy from (bad)
> examples (and arguably, any example you do not really understand is a
> bad example).
Unfortunately.
> (It does not allow *all* memory and *all* constants, btw... And the
> condition for registers is not really "general register", whatever that
> means...
I think that means general purpose registers. I.e., it won't use, say
FPU, XMM or whatever special regs.
What does the asm() parsing code in gcc do for "g"? There should be
some logic which constraints what register is valid...
> I hope no one ever told you our documentation does not have white
> lies!)
I have convinced myself of this a couple of times already so I either go
ask our gcc friends or go look straight at gcc source. It is useful to
know folks which hack on it so that I can ask them stupid questions and
not go off into the weeds, trying to figure out what the documentation
says.
But hey, if that gets the documentation improved, that's a win-win
situation right there. Might even make people copying from bad examples
to go look at the docs first...
:-)
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-11-02 18:34 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 6:17 [PATCH v5 00/17] HSM driver for ACRN hypervisor shuo.a.liu
2020-10-19 6:17 ` [PATCH v5 01/17] docs: acrn: Introduce ACRN shuo.a.liu
2020-10-19 6:17 ` [PATCH v5 02/17] x86/acrn: Introduce acrn_{setup, remove}_intr_handler() shuo.a.liu
2020-10-19 6:17 ` [PATCH v5 03/17] x86/acrn: Introduce an API to check if a VM is privileged shuo.a.liu
2020-11-02 14:37 ` Borislav Petkov
2020-11-03 6:27 ` Shuo A Liu
2020-11-03 10:25 ` Borislav Petkov
2020-11-04 3:50 ` Shuo A Liu
2020-11-04 18:51 ` Borislav Petkov
2020-11-05 3:25 ` Shuo A Liu
2020-10-19 6:17 ` [PATCH v5 04/17] x86/acrn: Introduce hypercall interfaces shuo.a.liu
2020-10-19 21:53 ` Nick Desaulniers
2020-10-19 22:15 ` Arvind Sankar
2020-10-20 1:38 ` Shuo A Liu
2020-10-20 2:08 ` Arvind Sankar
2020-10-20 2:30 ` Shuo A Liu
2020-10-20 14:16 ` Arvind Sankar
2020-10-21 1:16 ` Shuo A Liu
2020-11-02 14:56 ` Borislav Petkov
2020-11-02 16:09 ` Segher Boessenkool
2020-11-02 17:19 ` Borislav Petkov
2020-11-02 18:10 ` Segher Boessenkool
2020-11-02 18:34 ` Borislav Petkov [this message]
2020-11-02 20:01 ` Segher Boessenkool
2020-11-02 22:54 ` Borislav Petkov
2020-11-02 23:18 ` Segher Boessenkool
2020-11-03 16:44 ` Borislav Petkov
2020-11-03 18:47 ` Segher Boessenkool
2020-11-03 19:43 ` Borislav Petkov
2020-10-19 6:17 ` [PATCH v5 05/17] virt: acrn: Introduce ACRN HSM basic driver shuo.a.liu
2020-10-19 6:17 ` [PATCH v5 06/17] virt: acrn: Introduce VM management interfaces shuo.a.liu
2020-11-04 19:02 ` Greg Kroah-Hartman
2020-11-05 3:10 ` Shuo A Liu
2020-11-05 6:29 ` Greg Kroah-Hartman
2020-11-05 7:35 ` Shuo A Liu
2020-11-05 8:26 ` Greg Kroah-Hartman
2020-11-05 9:02 ` Shuo A Liu
2020-11-05 9:16 ` Greg Kroah-Hartman
2020-11-05 12:48 ` Shuo A Liu
2020-11-05 13:04 ` Greg Kroah-Hartman
2020-10-19 6:17 ` [PATCH v5 07/17] virt: acrn: Introduce an ioctl to set vCPU registers state shuo.a.liu
2020-11-09 17:09 ` Greg Kroah-Hartman
2020-11-10 13:14 ` Shuo A Liu
2020-11-10 14:54 ` Greg Kroah-Hartman
2020-11-11 9:54 ` Shuo A Liu
2020-11-11 10:28 ` Greg Kroah-Hartman
2020-11-11 12:03 ` Shuo A Liu
2020-11-11 12:29 ` Greg Kroah-Hartman
2020-11-11 16:55 ` Shuo A Liu
2020-10-19 6:17 ` [PATCH v5 08/17] virt: acrn: Introduce EPT mapping management shuo.a.liu
2020-10-19 6:17 ` [PATCH v5 09/17] virt: acrn: Introduce I/O request management shuo.a.liu
2020-10-19 6:17 ` [PATCH v5 10/17] virt: acrn: Introduce PCI configuration space PIO accesses combiner shuo.a.liu
2020-10-19 6:17 ` [PATCH v5 11/17] virt: acrn: Introduce interfaces for PCI device passthrough shuo.a.liu
2020-10-19 6:17 ` [PATCH v5 12/17] virt: acrn: Introduce interrupt injection interfaces shuo.a.liu
2020-10-19 6:17 ` [PATCH v5 13/17] virt: acrn: Introduce interfaces to query C-states and P-states allowed by hypervisor shuo.a.liu
2020-10-19 6:18 ` [PATCH v5 14/17] virt: acrn: Introduce I/O ranges operation interfaces shuo.a.liu
2020-10-19 6:18 ` [PATCH v5 15/17] virt: acrn: Introduce ioeventfd shuo.a.liu
2020-10-19 6:18 ` [PATCH v5 16/17] virt: acrn: Introduce irqfd shuo.a.liu
2020-10-19 6:18 ` [PATCH v5 17/17] virt: acrn: Introduce an interface for Service VM to control vCPU shuo.a.liu
2020-10-21 15:19 ` [PATCH v5 00/17] HSM driver for ACRN hypervisor Dave Hansen
2020-10-26 0:39 ` Shuo A Liu
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