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From: "tip-bot2 for Dexuan Cui" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Dexuan Cui <decui@microsoft.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	David Woodhouse <dwmw@amazon.co.uk>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: x86/apic] iommu/hyper-v: Remove I/O-APIC ID check from hyperv_irq_remapping_select()
Date: Wed, 02 Dec 2020 10:28:02 -0000	[thread overview]
Message-ID: <160690488231.3364.5753445245767279779.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20201202004510.1818-1-decui@microsoft.com>

The following commit has been merged into the x86/apic branch of tip:

Commit-ID:     26ab12bb9d96133b7880141d68b5e01a8783de9d
Gitweb:        https://git.kernel.org/tip/26ab12bb9d96133b7880141d68b5e01a8783de9d
Author:        Dexuan Cui <decui@microsoft.com>
AuthorDate:    Tue, 01 Dec 2020 16:45:10 -08:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 02 Dec 2020 11:22:55 +01:00

iommu/hyper-v: Remove I/O-APIC ID check from hyperv_irq_remapping_select()

commit a491bb19f728 ("iommu/hyper-v: Implement select() method on remapping
irqdomain") restricted the irq_domain_ops::select() callback to match on
I/O-APIC index 0, which was correct until the parameter was changed to
carry the I/O APIC ID in commit f36a74b9345a.

If the ID is not 0 then the match fails. Therefore I/O-APIC init fails to
retrieve the parent irqdomain for the I/O-APIC resulting in a boot panic:

    kernel BUG at arch/x86/kernel/apic/io_apic.c:2408!

Fix it by matching the I/O-APIC independent of the ID as there is only one
I/O APIC emulated by Hyper-V.

[ tglx: Amended changelog ]

Fixes: f36a74b9345a ("x86/ioapic: Use I/O-APIC ID for finding irqdomain, not index")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20201202004510.1818-1-decui@microsoft.com
---
 drivers/iommu/hyperv-iommu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-iommu.c
index 9438daa..1d21a0b 100644
--- a/drivers/iommu/hyperv-iommu.c
+++ b/drivers/iommu/hyperv-iommu.c
@@ -105,8 +105,8 @@ static int hyperv_irq_remapping_select(struct irq_domain *d,
 				       struct irq_fwspec *fwspec,
 				       enum irq_domain_bus_token bus_token)
 {
-	/* Claim only the first (and only) I/OAPIC */
-	return x86_fwspec_is_ioapic(fwspec) && fwspec->param[0] == 0;
+	/* Claim the only I/O APIC emulated by Hyper-V */
+	return x86_fwspec_is_ioapic(fwspec);
 }
 
 static const struct irq_domain_ops hyperv_ir_domain_ops = {

      parent reply	other threads:[~2020-12-02 10:29 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-02  0:45 [PATCH] iommu/hyper-v: Fix panic on a host without the 15-bit APIC ID support Dexuan Cui
2020-12-02  1:28 ` Woodhouse, David
2020-12-02  9:56 ` Thomas Gleixner
2020-12-02 19:53   ` Dexuan Cui
2020-12-02 10:28 ` tip-bot2 for Dexuan Cui [this message]

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