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Re: [PATCH] x86: enable interrupts around dump_execstate()
- To: Roger Pau Monné <roger.pau@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Wed, 14 Sep 2022 10:14:50 +0200
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- Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>
- Delivery-date: Wed, 14 Sep 2022 08:15:05 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 13.09.2022 16:50, Roger Pau Monné wrote:
> On Mon, Dec 13, 2021 at 04:12:55PM +0100, Jan Beulich wrote:
>> show_hvm_stack() requires interrupts to be enabled to avoids triggering
>> the consistency check in check_lock() for the p2m lock. To do so in
>> spurious_interrupt() requires adding reentrancy protection / handling
>> there.
>
> There's also an ASSERT(!in_irq()) in _percpu_write_lock() that will
> trigger when trying to acquire the p2m lock from spurious_interrupt()
> context, as p2m_lock() -> mm_write_lock() -> _mm_write_lock ->
> percpu_write_lock().
s/will/may/ since spurious_interrupt() doesn't itself use irq_enter(),
but yes - we could nest inside a lower priority interrupt. I'll make
local_irq_enable() depend on !in_irq().
Jan
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