linux-kernel - Re: [PATCH v3 02/11] x86/irq: Define NMI source vectors

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Date: Mon, 1 Jul 2024 10:16:19 -0700
From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
To: Xin Li <xin@...or.com>
Cc: X86 Kernel <x86@...nel.org>, Sean Christopherson <seanjc@...gle.com>,
 LKML <linux-kernel@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>,
 Dave Hansen <dave.hansen@...el.com>, "H. Peter Anvin" <hpa@...or.com>, Ingo
 Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Xin Li
 <xin3.li@...el.com>, linux-perf-users@...r.kernel.org, Peter Zijlstra
 <peterz@...radead.org>, Paolo Bonzini <pbonzini@...hat.com>, Tony Luck
 <tony.luck@...el.com>, Andy Lutomirski <luto@...nel.org>, acme@...nel.org,
 kan.liang@...ux.intel.com, Andi Kleen <andi.kleen@...el.com>, "Mehta,
 Sohil" <sohil.mehta@...el.com>, jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH v3 02/11] x86/irq: Define NMI source vectors


On Sat, 29 Jun 2024 11:32:10 -0700, Xin Li <xin@...or.com> wrote:

> On 6/28/2024 1:18 PM, Jacob Pan wrote:
> > When NMI-source reporting is supported, each logical processor maintains
> > a 16-bit NMI-source bitmap. It is up to the system software to assign
> > NMI sources for their matching vector (bit position) in the bitmap.
> > 
> > Notice that NMI source vector is in a different namespace than the IDT
> > vectors. Though they share the same programming interface/field in the
> > NMI originator.
> > 
> > This initial allocation of the NMI sources are limited to local NMIs in
> > that there is no external device NMI usage yet.
> > 
> > Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> > ---
> >   arch/x86/include/asm/irq_vectors.h | 28 ++++++++++++++++++++++++++++
> >   1 file changed, 28 insertions(+)
> > 
> > diff --git a/arch/x86/include/asm/irq_vectors.h
> > b/arch/x86/include/asm/irq_vectors.h index 13aea8fc3d45..e4cd33bc4fef
> > 100644 --- a/arch/x86/include/asm/irq_vectors.h
> > +++ b/arch/x86/include/asm/irq_vectors.h
> > @@ -105,6 +105,34 @@
> >   
> >   #define NR_VECTORS			 256
> >   
> > +/*
> > + * The NMI senders specify the NMI source vector as an 8bit integer in
> > their  
> 
> s/The NMI senders/NMI senders/
will do

> > + * vector field with NMI delivery mode. A local APIC receiving an NMI
> > will
> > + * set the corresponding bit in a 16bit bitmask, which is accumulated
> > until
> > + * the NMI is delivered.
> > + * When a sender didn't specify an NMI source vector the source vector
> > will
> > + * be 0, which will result in bit 0 of the bitmask being set. For out
> > of
> > + * bounds vectors >= 16 bit 0 will also be set.
> > + * When bit 0 is set, system software must invoke all registered NMI
> > handlers
> > + * as if NMI source feature is not enabled.  
> 
> Add empty lines in the above paragraph.
sounds good.

> > + *
> > + * Vector 2 is reserved for matching IDT NMI vector where it may be
> > hardcoded
> > + * by some external devices.
> > + *
> > + * The NMI source vectors are sorted by descending priority with the
> > exceptions
> > + * of 0 and 2.
> > + */
> > +#define NMI_SOURCE_VEC_UNKNOWN		0
> > +#define NMI_SOURCE_VEC_IPI_REBOOT	1	/* Crash reboot */
> > +#define NMI_SOURCE_VEC_IDT_NMI		2	/* Match IDT
> > NMI vector 2 */ +#define NMI_SOURCE_VEC_IPI_SMP_STOP	3	/*
> > Panic stop CPU */ +#define NMI_SOURCE_VEC_IPI_BT
> > 4	/* CPU backtrace */ +#define NMI_SOURCE_VEC_PMI
> > 5	/* PerfMon counters */ +#define NMI_SOURCE_VEC_IPI_KGDB
> > 	6	/* KGDB */ +#define NMI_SOURCE_VEC_IPI_MCE
> > 	7	/* MCE injection */ +#define
> > NMI_SOURCE_VEC_IPI_TEST		8	/* For remote and local
> > IPIs */ +#define NR_NMI_SOURCE_VECTORS		9  
> 
> Fix alignment.
Do you see alignment problem after the patch is applied? Alignment looks
good with vi, emacs, etc. passed checkpatch --strict.

> > +
> >   #ifdef CONFIG_X86_LOCAL_APIC
> >   #define FIRST_SYSTEM_VECTOR
> > POSTED_MSI_NOTIFICATION_VECTOR #else  
> 


Thanks,

Jacob