linux-kernel - [PATCH 05/15] x86/irq: Reserve a per CPU IDT vector for posted MSIs

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Message-Id: <20240126234237.547278-6-jacob.jun.pan@linux.intel.com>
Date: Fri, 26 Jan 2024 15:42:27 -0800
From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
To: LKML <linux-kernel@...r.kernel.org>,
	X86 Kernel <x86@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	iommu@...ts.linux.dev,
	Thomas Gleixner <tglx@...utronix.de>,
	"Lu Baolu" <baolu.lu@...ux.intel.com>,
	kvm@...r.kernel.org,
	Dave Hansen <dave.hansen@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Borislav Petkov" <bp@...en8.de>,
	"Ingo Molnar" <mingo@...hat.com>
Cc: Paul Luse <paul.e.luse@...el.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Jens Axboe <axboe@...nel.dk>,
	Raj Ashok <ashok.raj@...el.com>,
	"Tian, Kevin" <kevin.tian@...el.com>,
	maz@...nel.org,
	seanjc@...gle.com,
	"Robin Murphy" <robin.murphy@....com>,
	Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: [PATCH 05/15] x86/irq: Reserve a per CPU IDT vector for posted MSIs

When posted MSI is enabled, all device MSIs are multiplexed into a single
notification vector. MSI handlers will be de-multiplexed at run-time by
system software without IDT delivery.

Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
---
 arch/x86/include/asm/irq_vectors.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index 3a19904c2db6..08329bef5b1d 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -99,9 +99,16 @@
 
 #define LOCAL_TIMER_VECTOR		0xec
 
+/*
+ * Posted interrupt notification vector for all device MSIs delivered to
+ * the host kernel.
+ */
+#define POSTED_MSI_NOTIFICATION_VECTOR	0xeb
 #define NR_VECTORS			 256
 
-#ifdef CONFIG_X86_LOCAL_APIC
+#ifdef X86_POSTED_MSI
+#define FIRST_SYSTEM_VECTOR		POSTED_MSI_NOTIFICATION_VECTOR
+#elif defined(CONFIG_X86_LOCAL_APIC)
 #define FIRST_SYSTEM_VECTOR		LOCAL_TIMER_VECTOR
 #else
 #define FIRST_SYSTEM_VECTOR		NR_VECTORS
-- 
2.25.1