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

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Date: Fri, 28 Jun 2024 13:18:30 -0700
From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
To: 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>
Cc: 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 Pan <jacob.jun.pan@...ux.intel.com>
Subject: [PATCH v3 02/11] x86/irq: Define NMI source vectors

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
+ * 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.
+ *
+ * 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
+
 #ifdef CONFIG_X86_LOCAL_APIC
 #define FIRST_SYSTEM_VECTOR		POSTED_MSI_NOTIFICATION_VECTOR
 #else
-- 
2.25.1