From: Thomas Gleixner <tglx@linutronix.de>
To: andrew.cooper3@citrix.com, Xin Li <xin3.li@intel.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org,
kvm@vger.kernel.org, xen-devel@lists.xenproject.org
Cc: mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
x86@kernel.org, hpa@zytor.com, luto@kernel.org,
pbonzini@redhat.com, seanjc@google.com, peterz@infradead.org,
jgross@suse.com, ravi.v.shankar@intel.com, mhiramat@kernel.org,
jiangshanlai@gmail.com
Subject: Re: [PATCH v10 03/38] x86/msr: Add the WRMSRNS instruction support
Date: Fri, 15 Sep 2023 02:12:29 +0200 [thread overview]
Message-ID: <87v8cc1ehe.ffs@tglx> (raw)
In-Reply-To: <7ba4ae3e-f75d-66a8-7669-b6eb17c1aa1c@citrix.com>
On Fri, Sep 15 2023 at 00:46, andrew wrote:
> On 15/09/2023 12:00 am, Thomas Gleixner wrote:
>> So no. I'm fundamentally disagreeing with your recommendation. The way
>> forward is:
>>
>> 1) Provide the native variant for wrmsrns(), i.e. rename the proposed
>> wrmsrns() to native_wrmsr_ns() and have the X86_FEATURE_WRMSRNS
>> safety net as you pointed out.
>>
>> That function can be used in code which is guaranteed to be not
>> affected by the PV_XXL madness.
>>
>> 2) Come up with a sensible solution for the PV_XXL horrorshow
>>
>> 3) Implement a sane general variant of wrmsr_ns() which handles
>> both X86_FEATURE_WRMSRNS and X86_MISFEATURE_PV_XXL
>>
>> 4) Convert other code which benefits from the non-serializing variant
>> to wrmsr_ns()
>
> Well - point 1 is mostly work that needs reverting as part of completing
> point 3, and point 2 clearly needs doing irrespective of anything else.
No. #1 has a value on its own independent of the general variant in #3.
>> That function can be used in code which is guaranteed to be not
>> affected by the PV_XXL madness.
That makes a lot of sense because it's guaranteed to generate better
code than whatever we come up with for the PV_XXL nonsense.
Thanks,
tglx
next prev parent reply other threads:[~2023-09-15 0:12 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-14 4:47 [PATCH v10 00/38] x86: enable FRED for x86-64 Xin Li
2023-09-14 4:47 ` [PATCH v10 01/38] x86/cpufeatures: Add the cpu feature bit for WRMSRNS Xin Li
2023-09-14 4:47 ` [PATCH v10 02/38] x86/opcode: Add the WRMSRNS instruction to the x86 opcode map Xin Li
2023-09-15 5:47 ` Masami Hiramatsu
2023-09-14 4:47 ` [PATCH v10 03/38] x86/msr: Add the WRMSRNS instruction support Xin Li
2023-09-14 6:02 ` Juergen Gross
2023-09-14 13:01 ` andrew.cooper3
2023-09-14 14:05 ` andrew.cooper3
2023-09-14 23:00 ` Thomas Gleixner
2023-09-14 23:34 ` H. Peter Anvin
2023-09-14 23:46 ` andrew.cooper3
2023-09-15 0:12 ` Thomas Gleixner [this message]
2023-09-15 0:33 ` andrew.cooper3
2023-09-15 0:38 ` H. Peter Anvin
2023-09-15 1:46 ` andrew.cooper3
2023-09-15 2:06 ` H. Peter Anvin
2023-09-15 0:42 ` Thomas Gleixner
2023-09-15 1:01 ` H. Peter Anvin
2023-09-15 1:16 ` andrew.cooper3
2023-09-15 5:32 ` Juergen Gross
2023-09-20 15:00 ` Peter Zijlstra
2023-09-20 15:04 ` Juergen Gross
2023-09-20 7:58 ` Nikolay Borisov
2023-09-20 8:18 ` Li, Xin3
2023-09-22 8:16 ` Li, Xin3
2023-09-22 15:00 ` Thomas Gleixner
2023-09-22 23:21 ` Li, Xin3
2023-09-14 4:47 ` [PATCH v10 04/38] x86/entry: Remove idtentry_sysvec from entry_{32,64}.S Xin Li
2023-09-14 4:47 ` [PATCH v10 05/38] x86/trapnr: Add event type macros to <asm/trapnr.h> Xin Li
2023-09-14 14:22 ` andrew.cooper3
2023-09-14 4:47 ` [PATCH v10 06/38] Documentation/x86/64: Add a documentation for FRED Xin Li
2023-09-20 9:44 ` Nikolay Borisov
2023-09-14 4:47 ` [PATCH v10 07/38] x86/fred: Add Kconfig option for FRED (CONFIG_X86_FRED) Xin Li
2023-09-14 4:47 ` [PATCH v10 08/38] x86/cpufeatures: Add the cpu feature bit for FRED Xin Li
2023-09-14 6:03 ` Juergen Gross
2023-09-14 6:09 ` Jan Beulich
2023-09-14 13:15 ` andrew.cooper3
2023-09-15 1:07 ` Thomas Gleixner
2023-09-15 5:27 ` Juergen Gross
2023-09-14 4:47 ` [PATCH v10 09/38] x86/fred: Disable FRED support if CONFIG_X86_FRED is disabled Xin Li
2023-09-20 10:19 ` Nikolay Borisov
2023-09-14 4:47 ` [PATCH v10 10/38] x86/fred: Disable FRED by default in its early stage Xin Li
2023-09-14 4:47 ` [PATCH v10 11/38] x86/opcode: Add ERET[US] instructions to the x86 opcode map Xin Li
2023-09-14 4:47 ` [PATCH v10 12/38] x86/objtool: Teach objtool about ERET[US] Xin Li
2023-09-14 4:47 ` [PATCH v10 13/38] x86/cpu: Add X86_CR4_FRED macro Xin Li
2023-09-20 10:50 ` Nikolay Borisov
2023-09-20 17:25 ` Li, Xin3
2023-09-14 4:47 ` [PATCH v10 14/38] x86/cpu: Add MSR numbers for FRED configuration Xin Li
2023-09-14 4:47 ` [PATCH v10 15/38] x86/ptrace: Cleanup the definition of the pt_regs structure Xin Li
2023-09-14 4:47 ` [PATCH v10 16/38] x86/ptrace: Add FRED additional information to " Xin Li
2023-09-20 12:57 ` Nikolay Borisov
2023-09-20 17:23 ` Li, Xin3
2023-09-21 6:07 ` Nikolay Borisov
2023-09-21 6:24 ` Li, Xin3
2023-09-14 4:47 ` [PATCH v10 17/38] x86/fred: Add a new header file for FRED definitions Xin Li
2023-09-14 4:47 ` [PATCH v10 18/38] x86/fred: Reserve space for the FRED stack frame Xin Li
2023-09-14 4:47 ` [PATCH v10 19/38] x86/fred: Update MSR_IA32_FRED_RSP0 during task switch Xin Li
2023-09-14 4:47 ` [PATCH v10 20/38] x86/fred: Disallow the swapgs instruction when FRED is enabled Xin Li
2023-09-14 4:47 ` [PATCH v10 21/38] x86/fred: No ESPFIX needed " Xin Li
2023-09-14 4:47 ` [PATCH v10 22/38] x86/fred: Allow single-step trap and NMI when starting a new task Xin Li
2023-09-14 4:47 ` [PATCH v10 23/38] x86/fred: Make exc_page_fault() work for FRED Xin Li
2023-09-14 4:47 ` [PATCH v10 24/38] x86/idtentry: Incorporate definitions/declarations of the FRED entries Xin Li
2023-09-14 4:47 ` [PATCH v10 25/38] x86/fred: Add a debug fault entry stub for FRED Xin Li
2023-09-14 4:47 ` [PATCH v10 26/38] x86/fred: Add a NMI " Xin Li
2023-09-14 4:47 ` [PATCH v10 27/38] x86/fred: Add a machine check " Xin Li
2023-09-14 4:47 ` [PATCH v10 28/38] x86/fred: FRED entry/exit and dispatch code Xin Li
2023-09-21 9:48 ` Nikolay Borisov
2023-09-21 10:08 ` Thomas Gleixner
2023-09-21 17:54 ` Li, Xin3
2023-09-14 4:47 ` [PATCH v10 29/38] x86/traps: Add sysvec_install() to install a system interrupt handler Xin Li
2023-09-14 4:47 ` [PATCH v10 30/38] x86/fred: Let ret_from_fork_asm() jmp to asm_fred_exit_user when FRED is enabled Xin Li
2023-09-14 4:47 ` [PATCH v10 31/38] x86/fred: Fixup fault on ERETU by jumping to fred_entrypoint_user Xin Li
2023-09-14 4:47 ` [PATCH v10 32/38] x86/entry/calling: Allow PUSH_AND_CLEAR_REGS being used beyond actual entry code Xin Li
2023-09-14 4:48 ` [PATCH v10 33/38] x86/entry: Add fred_entry_from_kvm() for VMX to handle IRQ/NMI Xin Li
2023-09-20 17:54 ` Paolo Bonzini
2023-09-20 23:10 ` Li, Xin3
2023-09-21 12:11 ` Nikolay Borisov
2023-09-21 12:38 ` Paolo Bonzini
2023-09-14 4:48 ` [PATCH v10 34/38] KVM: VMX: Call fred_entry_from_kvm() for IRQ/NMI handling Xin Li
2023-09-20 17:54 ` Paolo Bonzini
2023-09-14 4:48 ` [PATCH v10 35/38] x86/syscall: Split IDT syscall setup code into idt_syscall_init() Xin Li
2023-09-14 4:48 ` [PATCH v10 36/38] x86/fred: Add fred_syscall_init() Xin Li
2023-09-19 8:28 ` Thomas Gleixner
2023-09-20 4:33 ` Li, Xin3
2023-09-20 8:18 ` Thomas Gleixner
2023-09-21 2:24 ` H. Peter Anvin
2023-09-14 4:48 ` [PATCH v10 37/38] x86/fred: Add FRED initialization functions Xin Li
2023-09-14 4:48 ` [PATCH v10 38/38] x86/fred: Invoke FRED initialization code to enable FRED Xin Li
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