Re: [PATCH] xen/arm: irq: Initialize the per-CPU IRQs while preparing the CPU

[Bertrand Marquis <Bertrand.Marquis@arm.com>]

Sorry, this was suppose to be off list but nothing wrong in making everybody aware I guess :-)

Bertrand

> On 24 Jun 2022, at 10:31, Bertrand Marquis <Bertrand.Marquis@arm.com> wrote:
> 
> Hi Julien,
> 
> [OFFLIST]
> 
>> On 14 Jun 2022, at 10:41, Julien Grall <julien@xen.org> wrote:
>> 
>> From: Julien Grall <jgrall@amazon.com>
>> 
>> Commit 5047cd1d5dea "xen/common: Use enhanced ASSERT_ALLOC_CONTEXT in
>> xmalloc()" extended the checks in _xmalloc() to catch any use of the
>> helpers from context with interrupts disabled.
>> 
>> Unfortunately, the rule is not followed when initializing the per-CPU
>> IRQs:
>> 
>> (XEN) Xen call trace:
>> (XEN) [<002389f4>] _xmalloc+0xfc/0x314 (PC)
>> (XEN) [<00000000>] 00000000 (LR)
>> (XEN) [<0021a7c4>] init_one_irq_desc+0x48/0xd0
>> (XEN) [<002807a8>] irq.c#init_local_irq_data+0x48/0xa4
>> (XEN) [<00280834>] init_secondary_IRQ+0x10/0x2c
>> (XEN) [<00288fa4>] start_secondary+0x194/0x274
>> (XEN) [<40010170>] 40010170
>> (XEN)
>> (XEN)
>> (XEN) ****************************************
>> (XEN) Panic on CPU 2:
>> (XEN) Assertion '!in_irq() && (local_irq_is_enabled() || num_online_cpus() <= 1)' failed at common/xmalloc_tlsf.c:601
>> (XEN) ****************************************
>> 
>> This is happening because zalloc_cpumask_var() may allocate memory
>> if NR_CPUS is > 2 * sizeof(unsigned long).
>> 
>> Avoid the problem by allocate the per-CPU IRQs while preparing the
>> CPU.
>> 
>> This also has the benefit to remove a BUG_ON() in the secondary CPU
>> code.
>> 
>> Signed-off-by: Julien Grall <jgrall@amazon.com>
> 
> I still have issues after applying this patch on qemu-arm32:
> 
> (XEN) CPU0: Guest atomics will try 1 times before pausing the domain^M^M
> (XEN) Bringing up CPU1^M^M
> (XEN) CPU1: Guest atomics will try 1 times before pausing the domain^M^M
> (XEN) Assertion 'test_bit(_IRQ_DISABLED, &desc->status)' failed at arch/arm/gic.c:124^M^M
> (XEN) ----[ Xen-4.17-unstable arm32 debug=y Not tainted ]----^M^M
> (XEN) CPU: 1^M^M
> (XEN) PC: 0026f134 gic_route_irq_to_xen+0xa4/0xb0^M^M
> (XEN) CPSR: 400001da MODE:Hypervisor^M^M
> (XEN) R0: 00000120 R1: 000000a0 R2: 40002538 R3: 00000000^M^M
> (XEN) R4: 40004f00 R5: 000000a0 R6: 40002538 R7: 8000015a^M^M
> (XEN) R8: 00000000 R9: 40004f14 R10:3fe10000 R11:43fefeec R12:40002ff8^M^M
> (XEN) HYP: SP: 43fefed4 LR: 0026f0b8^M^M
> (XEN) ^M^M
> (XEN) VTCR_EL2: 00000000^M^M
> (XEN) VTTBR_EL2: 0000000000000000^M^M
> (XEN) ^M^M
> (XEN) SCTLR_EL2: 30cd187f^M^M
> (XEN) HCR_EL2: 00000038^M^M
> (XEN) TTBR0_EL2: 00000000bfffa000^M^M
> (XEN) ^M^M
> (XEN) ESR_EL2: 00000000^M^M
> (XEN) HPFAR_EL2: 00000000^M^M
> (XEN) HDFAR: 00000000^M^M
> (XEN) HIFAR: 00000000^M^M
> (XEN) ^M^M
> (XEN) Xen stack trace from sp=43fefed4:^M^M
> (XEN) 00000000 40004f00 00000000 40002538 8000015a 43feff0c 00272a4c 40002538^M^M
> (XEN) 002a47c4 00000019 00000000 0026ee28 40010000 43feff2c 00272b30 00309298^M^M
> (XEN) 00000001 0033b248 00000001 00000000 40010000 43feff3c 0026f7ac 00000000^M^M
> (XEN) 00201828 43feff54 0027ac3c bfffa000 00000000 00000000 00000001 00000000^M^M
> (XEN) 400100c0 00000000 00000000 00000000 00000000 00000000 00000000 00000000^M^M
> (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000^M^M
> (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000^M^M
> (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000^M^M
> (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000^M^M
> (XEN) 00000000 00000000 00000000^M^M
> (XEN) Xen call trace:^M^M
> (XEN) [<0026f134>] gic_route_irq_to_xen+0xa4/0xb0 (PC)^M^M
> (XEN) [<0026f0b8>] gic_route_irq_to_xen+0x28/0xb0 (LR)^M^M
> (XEN) [<00272a4c>] setup_irq+0x104/0x178^M^M
> (XEN) [<00272b30>] request_irq+0x70/0xb4^M^M
> (XEN) [<0026f7ac>] init_maintenance_interrupt+0x40/0x5c^M^M
> (XEN) [<0027ac3c>] start_secondary+0x1e8/0x270^M^M
> (XEN) [<400100c0>] 400100c0^M^M
> 
> Just wanted to signal before you push this out.
> 
> I will investigate deeper and come back to you.
> 
> Cheers
> Bertrand