linux-kernel - [PATCH 0/4] KVM: Async #PF fixes and cleanups

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Message-ID: <20240110011533.503302-1-seanjc@google.com>
Date: Tue,  9 Jan 2024 17:15:29 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	David Matlack <dmatlack@...gle.com>, Xu Yilun <yilun.xu@...ux.intel.com>, 
	Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH 0/4] KVM: Async #PF fixes and cleanups

Fix a use-after-module-unload bug in the async #PF code by ensuring all
workqueue items fully complete before tearing down vCPUs.  Do a bit of
cleanup to try and make the code slightly more readable.

Side topic, I'm pretty s390's flic_set_attr() is broken/racy.  The async #PF
code assumes that only the vCPU can invoke
kvm_clear_async_pf_completion_queue(), as there are multiple assets that
are effectively protected by vcpu->mutex.  I don't any real world VMMs
trigger the race(s), but AFAICT it's a bug.  I think/assume taking all
vCPUs' mutexes would plug the hole?

Sean Christopherson (4):
  KVM: Always flush async #PF workqueue when vCPU is being destroyed
  KVM: Put mm immediately after async #PF worker completes remote gup()
  KVM: Get reference to VM's address space in the async #PF worker
  KVM: Nullify async #PF worker's "apf" pointer as soon as it might be
    freed

 include/linux/kvm_host.h |  1 -
 virt/kvm/async_pf.c      | 79 ++++++++++++++++++++++++++++------------
 2 files changed, 55 insertions(+), 25 deletions(-)

base-commit: 1c6d984f523f67ecfad1083bb04c55d91977bb15
-- 
2.43.0.472.g3155946c3a-goog