From: Sean Christopherson <seanjc@google.com>
To: Xin Li <xin3.li@intel.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
kvm@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com,
peterz@infradead.org, andrew.cooper3@citrix.com,
pbonzini@redhat.com, ravi.v.shankar@intel.com
Subject: Re: [PATCH v5 34/34] KVM: x86/vmx: execute "int $2" to handle NMI in NMI caused VM exits when FRED is enabled
Date: Wed, 22 Mar 2023 10:49:37 -0700 [thread overview]
Message-ID: <ZBs/sSJwr7zdOUsE@google.com> (raw)
In-Reply-To: <20230307023946.14516-35-xin3.li@intel.com>
On Mon, Mar 06, 2023, Xin Li wrote:
> Execute "int $2" to handle NMI in NMI caused VM exits when FRED is enabled.
>
> Like IRET for IDT, ERETS/ERETU are required to end the NMI handler for FRED
> to unblock NMI ASAP (w/ bit 28 of CS set).
That's "CS" on the stack correct? Is bit 28 set manually by software, or is it
set automatically by hardware? If it's set by hardware, does "int $2" actually
set the bit since it's not a real NMI?
> And there are 2 approaches to
> invoke the FRED NMI handler:
> 1) execute "int $2", let the h/w do the job.
> 2) create a FRED NMI stack frame on the current kernel stack with ASM,
> and then jump to fred_entrypoint_kernel in arch/x86/entry/entry_64_fred.S.
>
> 1) is preferred as we want less ASM.
Who is "we", and how much assembly are we talking about? E.g. I personally don't
mind a trampoline in KVM if it's small and/or can share code with existing
assembly subroutines.
next prev parent reply other threads:[~2023-03-22 17:49 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-07 2:39 [PATCH v5 00/34] x86: enable FRED for x86-64 Xin Li
2023-03-07 2:39 ` [PATCH v5 01/34] x86/traps: let common_interrupt() handle IRQ_MOVE_CLEANUP_VECTOR Xin Li
2023-03-07 2:39 ` [PATCH v5 02/34] x86/traps: add a system interrupt table for system interrupt dispatch Xin Li
2023-03-07 2:39 ` [PATCH v5 03/34] x86/traps: add install_system_interrupt_handler() Xin Li
2023-03-07 2:39 ` [PATCH v5 04/34] x86/traps: add external_interrupt() to dispatch external interrupts Xin Li
2023-03-20 15:36 ` Peter Zijlstra
2023-03-20 17:42 ` Peter Zijlstra
2023-03-20 23:47 ` Li, Xin3
2023-03-20 17:53 ` Li, Xin3
2023-03-07 2:39 ` [PATCH v5 05/34] x86/traps: export external_interrupt() for VMX IRQ reinjection Xin Li
2023-03-22 17:52 ` Sean Christopherson
2023-03-22 22:38 ` Li, Xin3
2023-03-07 2:39 ` [PATCH v5 06/34] x86/cpufeature: add the cpu feature bit for FRED Xin Li
2023-03-07 2:39 ` [PATCH v5 07/34] x86/opcode: add ERETU, ERETS instructions to x86-opcode-map Xin Li
2023-03-07 2:39 ` [PATCH v5 08/34] x86/objtool: teach objtool about ERETU and ERETS Xin Li
2023-03-07 2:39 ` [PATCH v5 09/34] x86/cpu: add X86_CR4_FRED macro Xin Li
2023-03-07 2:39 ` [PATCH v5 10/34] x86/fred: add Kconfig option for FRED (CONFIG_X86_FRED) Xin Li
2023-03-07 2:39 ` [PATCH v5 11/34] x86/fred: if CONFIG_X86_FRED is disabled, disable FRED support Xin Li
2023-03-07 2:39 ` [PATCH v5 12/34] x86/cpu: add MSR numbers for FRED configuration Xin Li
2023-03-07 2:39 ` [PATCH v5 13/34] x86/fred: header file for event types Xin Li
2023-03-07 2:39 ` [PATCH v5 14/34] x86/fred: header file with FRED definitions Xin Li
2023-03-07 2:39 ` [PATCH v5 15/34] x86/fred: make unions for the cs and ss fields in struct pt_regs Xin Li
2023-03-07 2:39 ` [PATCH v5 16/34] x86/fred: reserve space for the FRED stack frame Xin Li
2023-03-07 2:39 ` [PATCH v5 17/34] x86/fred: add a page fault entry stub for FRED Xin Li
2023-03-07 2:39 ` [PATCH v5 18/34] x86/fred: add a debug " Xin Li
2023-03-07 2:39 ` [PATCH v5 19/34] x86/fred: add a NMI " Xin Li
2023-03-07 2:39 ` [PATCH v5 20/34] x86/fred: add a machine check " Xin Li
2023-03-20 16:00 ` Peter Zijlstra
2023-03-21 0:04 ` Li, Xin3
2023-03-21 8:59 ` Peter Zijlstra
2023-03-21 16:38 ` Li, Xin3
2023-03-07 2:39 ` [PATCH v5 21/34] x86/fred: FRED entry/exit and dispatch code Xin Li
2023-03-07 2:39 ` [PATCH v5 22/34] x86/fred: FRED initialization code Xin Li
2023-03-17 13:35 ` Lai Jiangshan
2023-03-17 21:32 ` H. Peter Anvin
2023-03-18 6:33 ` Lai Jiangshan
2023-03-20 16:49 ` Peter Zijlstra
2023-03-21 0:12 ` Li, Xin3
2023-03-21 1:02 ` andrew.cooper3
2023-03-21 7:49 ` Li, Xin3
2023-03-22 16:29 ` Dave Hansen
2023-03-22 2:22 ` Li, Xin3
2023-03-22 4:01 ` Dave Hansen
2023-03-22 5:40 ` Li, Xin3
2023-03-22 18:25 ` andrew.cooper3
2023-03-20 16:44 ` Peter Zijlstra
2023-03-21 0:13 ` Li, Xin3
2023-03-07 2:39 ` [PATCH v5 23/34] x86/fred: update MSR_IA32_FRED_RSP0 during task switch Xin Li
2023-03-20 16:52 ` Peter Zijlstra
2023-03-20 23:54 ` Li, Xin3
2023-03-07 2:39 ` [PATCH v5 24/34] x86/fred: let ret_from_fork() jmp to fred_exit_user when FRED is enabled Xin Li
2023-03-07 2:39 ` [PATCH v5 25/34] x86/fred: disallow the swapgs instruction " Xin Li
2023-03-20 16:54 ` Peter Zijlstra
2023-03-20 17:58 ` Li, Xin3
2023-03-07 2:39 ` [PATCH v5 26/34] x86/fred: no ESPFIX needed " Xin Li
2023-03-07 2:39 ` [PATCH v5 27/34] x86/fred: allow single-step trap and NMI when starting a new thread Xin Li
2023-03-07 2:39 ` [PATCH v5 28/34] x86/fred: fixup fault on ERETU by jumping to fred_entrypoint_user Xin Li
2023-03-17 9:39 ` Lai Jiangshan
2023-03-17 9:55 ` andrew.cooper3
2023-03-17 13:02 ` Lai Jiangshan
2023-03-17 21:23 ` H. Peter Anvin
2023-03-17 21:00 ` H. Peter Anvin
2023-03-18 7:55 ` Li, Xin3
2023-03-07 2:39 ` [PATCH v5 29/34] x86/ia32: do not modify the DPL bits for a null selector Xin Li
2023-03-07 2:39 ` [PATCH v5 30/34] x86/fred: allow FRED systems to use interrupt vectors 0x10-0x1f Xin Li
2023-03-07 2:39 ` [PATCH v5 31/34] x86/fred: allow dynamic stack frame size Xin Li
2023-03-07 2:39 ` [PATCH v5 32/34] x86/fred: disable FRED by default in its early stage Xin Li
2023-03-07 2:39 ` [PATCH v5 33/34] KVM: x86/vmx: call external_interrupt() to handle IRQ in IRQ caused VM exits Xin Li
2023-03-22 17:57 ` Sean Christopherson
2023-03-07 2:39 ` [PATCH v5 34/34] KVM: x86/vmx: execute "int $2" to handle NMI in NMI caused VM exits when FRED is enabled Xin Li
2023-03-07 22:00 ` Li, Xin3
2023-03-22 17:49 ` Sean Christopherson [this message]
2023-03-22 23:03 ` andrew.cooper3
2023-03-22 23:42 ` Sean Christopherson
2023-03-23 0:26 ` Li, Xin3
2023-03-24 17:45 ` Li, Xin3
2023-03-22 23:43 ` Li, Xin3
2023-03-11 9:58 ` [PATCH v5 00/34] x86: enable FRED for x86-64 Kang, Shan
2023-03-11 21:29 ` Li, Xin3
2023-03-20 7:40 ` Kang, Shan
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