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Saurabh Sengar 55fc2246c4 x86/ioapic: Don't return 0 from arch_dynirq_lower_bound()

[ Upstream commit 5af507bef93c09a94fb8f058213b489178f4cbe5 ]

arch_dynirq_lower_bound() is invoked by the core interrupt code to
retrieve the lowest possible Linux interrupt number for dynamically
allocated interrupts like MSI.

The x86 implementation uses this to exclude the IO/APIC GSI space.
This works correctly as long as there is an IO/APIC registered, but
returns 0 if not. This has been observed in VMs where the BIOS does
not advertise an IO/APIC.

0 is an invalid interrupt number except for the legacy timer interrupt
on x86. The return value is unchecked in the core code, so it ends up
to allocate interrupt number 0 which is subsequently considered to be
invalid by the caller, e.g. the MSI allocation code.

The function has already a check for 0 in the case that an IO/APIC is
registered, as ioapic_dynirq_base is 0 in case of device tree setups.

Consolidate this and zero check for both ioapic_dynirq_base and gsi_top,
which is used in the case that no IO/APIC is registered.

Fixes: 3e5bedc2c258 ("x86/apic: Fix arch_dynirq_lower_bound() bug for DT enabled machines")
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/1679988604-20308-1-git-send-email-ssengar@linux.microsoft.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

2023-05-17 11:47:45 +02:00

alpha

alpha: fix R_ALPHA_LITERAL reloc for large modules

2023-03-17 08:45:14 +01:00

arc

arch: setup PF_IO_WORKER threads like PF_KTHREAD

2023-01-04 11:39:22 +01:00

arm

ARM: dts: gta04: fix excess dma channel usage

2023-05-17 11:47:42 +02:00

arm64

arm64: dts: qcom: msm8996: Fix the PCI I/O port range