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From: Thomas Gleixner <tglx@linutronix.de>
To: "Li, Xin3" <xin3.li@intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"x86@kernel.org" <x86@kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Cc: "mingo@redhat.com" <mingo@redhat.com>,
	"bp@alien8.de" <bp@alien8.de>,
	"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
	"Christopherson,, Sean" <seanjc@google.com>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"Shankar, Ravi V" <ravi.v.shankar@intel.com>,
	"jiangshanlai@gmail.com" <jiangshanlai@gmail.com>,
	"Kang, Shan" <shan.kang@intel.com>
Subject: RE: [PATCH v8 30/33] x86/fred: allow dynamic stack frame size
Date: Tue, 06 Jun 2023 15:27:25 +0200	[thread overview]
Message-ID: <87fs74lo02.ffs@tglx> (raw)
In-Reply-To: <SA1PR11MB673430AC2D6F20C5F77FC83AA852A@SA1PR11MB6734.namprd11.prod.outlook.com>

On Tue, Jun 06 2023 at 06:18, Xin3 Li wrote:
>> > A FRED stack frame could contain different amount of information for
>> > This approach also works for IDT, thus we unify the code.
>> 
>> And thereby remove the useful comment and replace it with an undocumented
>> macro mess.
>> 
>> I'm simply refusing to review this. It's not my job to understand this
>> undocumented hackery.
>> 
>
> I believe it's a nice idea to allow dynamic stack frame size, at least for
> FRED.

Believe belongs in the realm of religion. What we need here are proper
facts, explanations and justifications. Nice ideas are not helpful when
they are not having a value.

> It's totally my bad that I didn't make it meet the minimum standards,
> I will rewrite the commit message and add better comments.
>
> After a second thought, I probably should only apply the change to FRED for
> 2 reasons, the change seems problematic with ESPFIX (which FRED
> doesn't need),

Indeed. Making this FRED only is going to need even more justification.

> and such corner cases are hard to test (self-tests needed?)

There is a test. It's not that hard to find:

# git grep -li ESPFIX tools/testing/selftests/
tools/testing/selftests/x86/sigreturn.c

Thanks,

        tglx

  reply	other threads:[~2023-06-06 13:27 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-10  8:14 [PATCH v8 00/33] x86: enable FRED for x86-64 Xin Li
2023-04-10  8:14 ` [PATCH v8 01/33] x86/traps: let common_interrupt() handle IRQ_MOVE_CLEANUP_VECTOR Xin Li
2023-05-07 11:59   ` Borislav Petkov
2023-06-03 19:19     ` Li, Xin3
2023-06-03 20:51   ` Thomas Gleixner
2023-06-05 17:07     ` Thomas Gleixner
2023-06-05 17:09       ` H. Peter Anvin
2023-06-06 20:09         ` Thomas Gleixner
2023-06-06 23:16           ` Li, Xin3
2023-06-19  8:00           ` Li, Xin3
2023-06-19 14:22             ` Thomas Gleixner
2023-06-19 18:47               ` Li, Xin3
2023-06-19 19:16                 ` H. Peter Anvin
2023-06-20  0:04                   ` Li, Xin3
2023-04-10  8:14 ` [PATCH v8 02/33] x86/fred: make unions for the cs and ss fields in struct pt_regs Xin Li
2023-06-03  9:48   ` Borislav Petkov
2023-06-05 12:07   ` Thomas Gleixner
2023-06-05 17:12     ` H. Peter Anvin
2023-06-05 17:29       ` Thomas Gleixner
2023-04-10  8:14 ` [PATCH v8 03/33] x86/traps: add a system interrupt table for system interrupt dispatch Xin Li
2023-06-05  8:34   ` Thomas Gleixner
2023-06-06  8:05     ` Li, Xin3
2023-06-05  8:38   ` Thomas Gleixner
2023-06-05  8:39   ` Thomas Gleixner
2023-04-10  8:14 ` [PATCH v8 04/33] x86/traps: add install_system_interrupt_handler() Xin Li
2023-06-05  8:57   ` Thomas Gleixner
2023-06-06  5:46     ` Li, Xin3
2023-04-10  8:14 ` [PATCH v8 05/33] x86/traps: add external_interrupt() to dispatch external interrupts Xin Li
2023-06-05 11:56   ` Thomas Gleixner
2023-06-05 17:52     ` Thomas Gleixner
2023-06-19 19:16     ` Li, Xin3
2023-06-19 21:13       ` Thomas Gleixner
2023-06-20  0:16         ` Li, Xin3
2023-04-10  8:14 ` [PATCH v8 06/33] x86/cpufeature: add the cpu feature bit for FRED Xin Li
2023-04-10  8:14 ` [PATCH v8 07/33] x86/opcode: add ERETU, ERETS instructions to x86-opcode-map Xin Li
2023-04-10  8:14 ` [PATCH v8 08/33] x86/objtool: teach objtool about ERETU and ERETS Xin Li
2023-04-10  8:14 ` [PATCH v8 09/33] x86/cpu: add X86_CR4_FRED macro Xin Li
2023-06-05 12:01   ` Thomas Gleixner
2023-06-05 17:06     ` H. Peter Anvin
2023-06-05 17:19     ` H. Peter Anvin
2023-04-10  8:14 ` [PATCH v8 10/33] x86/fred: add Kconfig option for FRED (CONFIG_X86_FRED) Xin Li
2023-04-10  8:14 ` [PATCH v8 11/33] x86/fred: if CONFIG_X86_FRED is disabled, disable FRED support Xin Li
2023-04-10  8:14 ` [PATCH v8 12/33] x86/cpu: add MSR numbers for FRED configuration Xin Li
2023-04-10  8:14 ` [PATCH v8 13/33] x86/fred: header file for event types Xin Li
2023-04-10  8:14 ` [PATCH v8 14/33] x86/fred: header file with FRED definitions Xin Li
2023-04-10  8:14 ` [PATCH v8 15/33] x86/fred: reserve space for the FRED stack frame Xin Li
2023-04-10  8:14 ` [PATCH v8 16/33] x86/fred: add a page fault entry stub for FRED Xin Li
2023-04-10  8:14 ` [PATCH v8 17/33] x86/fred: add a debug " Xin Li
2023-04-10  8:14 ` [PATCH v8 18/33] x86/fred: add a NMI " Xin Li
2023-04-10  8:14 ` [PATCH v8 19/33] x86/fred: add a machine check " Xin Li
2023-04-10  8:14 ` [PATCH v8 20/33] x86/fred: FRED entry/exit and dispatch code Xin Li
2023-06-05 13:21   ` Thomas Gleixner
2023-04-10  8:14 ` [PATCH v8 21/33] x86/fred: FRED initialization code Xin Li
2023-06-05 12:15   ` Thomas Gleixner
2023-06-05 13:41   ` Thomas Gleixner
2023-04-10  8:14 ` [PATCH v8 22/33] x86/fred: update MSR_IA32_FRED_RSP0 during task switch Xin Li
2023-04-10  8:14 ` [PATCH v8 23/33] x86/fred: let ret_from_fork() jmp to fred_exit_user when FRED is enabled Xin Li
2023-04-10  8:14 ` [PATCH v8 24/33] x86/fred: disallow the swapgs instruction " Xin Li
2023-06-05 13:47   ` Thomas Gleixner
2023-04-10  8:14 ` [PATCH v8 25/33] x86/fred: no ESPFIX needed " Xin Li
2023-04-10  8:14 ` [PATCH v8 26/33] x86/fred: allow single-step trap and NMI when starting a new thread Xin Li
2023-06-05 13:50   ` Thomas Gleixner
2023-06-05 13:52     ` Thomas Gleixner
2023-04-10  8:14 ` [PATCH v8 27/33] x86/fred: fixup fault on ERETU by jumping to fred_entrypoint_user Xin Li
2023-04-10  8:14 ` [PATCH v8 28/33] x86/ia32: do not modify the DPL bits for a null selector Xin Li
2023-04-10  8:14 ` [PATCH v8 29/33] x86/fred: allow FRED systems to use interrupt vectors 0x10-0x1f Xin Li
2023-06-05 14:06   ` Thomas Gleixner
2023-06-05 16:55     ` H. Peter Anvin
2023-04-10  8:14 ` [PATCH v8 30/33] x86/fred: allow dynamic stack frame size Xin Li
2023-06-05 14:11   ` Thomas Gleixner
2023-06-06  6:18     ` Li, Xin3
2023-06-06 13:27       ` Thomas Gleixner [this message]
2023-06-06 23:08         ` H. Peter Anvin
2023-04-10  8:14 ` [PATCH v8 31/33] x86/fred: BUG() when ERETU with %rsp not equal to that when the ring 3 event was just delivered Xin Li
2023-06-05 14:15   ` Thomas Gleixner
2023-06-05 16:42     ` H. Peter Anvin
2023-06-05 17:16       ` Thomas Gleixner
2023-04-10  8:14 ` [PATCH v8 32/33] x86/fred: disable FRED by default in its early stage Xin Li
2023-04-10  8:14 ` [PATCH v8 33/33] KVM: x86/vmx: refactor VMX_DO_EVENT_IRQOFF to generate FRED stack frames Xin Li
2023-04-10 21:50   ` Sean Christopherson
2023-04-11  5:06     ` Li, Xin3
2023-04-11 18:34       ` Sean Christopherson
2023-04-11 22:50         ` Li, Xin3
2023-04-12 18:26     ` Li, Xin3
2023-04-12 19:37       ` Sean Christopherson
2023-04-10 18:37 ` [PATCH v8 00/33] x86: enable FRED for x86-64 Dave Hansen
2023-04-10 19:14   ` Li, Xin3
2023-04-10 19:32     ` Borislav Petkov
2023-04-10 19:38       ` Dave Hansen
2023-04-10 20:52         ` Li, Xin3
2023-04-11  4:14       ` Li, Xin3
2023-04-10 18:49 ` Dave Hansen
2023-04-10 19:16   ` Li, Xin3
2023-06-05 17:11     ` Thomas Gleixner
2023-06-05 17:22 ` H. Peter Anvin
2023-06-05 17:32   ` Thomas Gleixner

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