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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: x86@kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org, Juergen Gross <jgross@suse.com>,
	Stefano Stabellini <sstabellini@kernel.org>
Subject: [PATCH v2 3/3] x86/idt: Keep spurious entries unset in system_vectors
Date: Tue, 28 Apr 2020 11:38:24 +0200	[thread overview]
Message-ID: <20200428093824.1451532-4-vkuznets@redhat.com> (raw)
In-Reply-To: <20200428093824.1451532-1-vkuznets@redhat.com>

With commit dc20b2d52653 ("x86/idt: Move interrupt gate initialization to
IDT code") non assigned system vectors are also marked as used in
'used_vectors' (now 'system_vectors') bitmap. This makes checks in
arch_show_interrupts() whether a particular system vector is allocated to
always pass and e.g. 'Hyper-V reenlightenment interrupts' entry always
shows up in /proc/interrupts.

Another side effect of having all unassigned system vectors marked as used
is that irq_matrix_debug_show() will wrongly count them among 'System'
vectors.

As we now make sure alloc_intr_gate() is not called after init, it is
possible to leave unused entries in 'system_vectors' unset to fix the
issues.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/kernel/idt.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index f95c3be00e5a..28500ccb835c 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -321,7 +321,11 @@ void __init idt_setup_apic_and_irq_gates(void)
 
 #ifdef CONFIG_X86_LOCAL_APIC
 	for_each_clear_bit_from(i, system_vectors, NR_VECTORS) {
-		set_bit(i, system_vectors);
+		/*
+		 * Don't set the non assigned system vectors in the
+		 * system_vectors bitmap. Otherwise they show up in
+		 * /proc/interrupts.
+		 */
 		entry = spurious_entries_start + 8 * (i - FIRST_SYSTEM_VECTOR);
 		set_intr_gate(i, entry);
 	}
-- 
2.25.3


  parent reply	other threads:[~2020-04-28  9:38 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-28  9:38 [PATCH v2 0/3] x86/idt: Minor alloc_intr_gate() sanitization Vitaly Kuznetsov
2020-04-28  9:38 ` [PATCH v2 1/3] x86/xen: Split HVM vector callback setup and interrupt gate allocation Vitaly Kuznetsov
2020-05-13 19:16   ` [tip: x86/entry] " tip-bot2 for Vitaly Kuznetsov
2020-04-28  9:38 ` [PATCH v2 2/3] x86/idt: Annotate alloc_intr_gate() with __init Vitaly Kuznetsov
2020-05-13 19:16   ` [tip: x86/entry] " tip-bot2 for Vitaly Kuznetsov
2020-04-28  9:38 ` Vitaly Kuznetsov [this message]
2020-05-13 19:16   ` [tip: x86/entry] x86/idt: Keep spurious entries unset in system_vectors tip-bot2 for Vitaly Kuznetsov
2020-05-13 12:57 ` [PATCH v2 0/3] x86/idt: Minor alloc_intr_gate() sanitization Vitaly Kuznetsov
2020-05-13 19:02   ` Thomas Gleixner
2020-05-14  8:10     ` Vitaly Kuznetsov

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