From: Matthew Rosato <mjrosato@linux.ibm.com> To: alex.williamson@redhat.com, pbonzini@redhat.com Cc: jgg@nvidia.com, cohuck@redhat.com, farman@linux.ibm.com, pmorel@linux.ibm.com, borntraeger@linux.ibm.com, frankja@linux.ibm.com, imbrenda@linux.ibm.com, david@redhat.com, akrowiak@linux.ibm.com, jjherne@linux.ibm.com, pasic@linux.ibm.com, zhenyuw@linux.intel.com, zhi.a.wang@intel.com, linux-s390@vger.kernel.org, kvm@vger.kernel.org, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] KVM: s390: pci: use asyncronous kvm put Date: Mon, 9 Jan 2023 15:10:37 -0500 [thread overview] Message-ID: <20230109201037.33051-3-mjrosato@linux.ibm.com> (raw) In-Reply-To: <20230109201037.33051-1-mjrosato@linux.ibm.com> It's possible that the kvm refcount will reach 0 at this point while the associated device is still in kvm device list - this would result in a deadlock on the vfio group lock. Avoid this possibility by using kvm_put_kvm_async to do the kvm_destroy_vm asynchronously. Fixes: 09340b2fca00 ("KVM: s390: pci: add routines to start/stop interpretive execution") Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com> --- arch/s390/kvm/pci.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c index ec51e810e381..d1d528438138 100644 --- a/arch/s390/kvm/pci.c +++ b/arch/s390/kvm/pci.c @@ -509,7 +509,7 @@ static int kvm_s390_pci_register_kvm(void *opaque, struct kvm *kvm) kvm_s390_pci_dev_release(zdev); mutex_unlock(&kvm->lock); mutex_unlock(&zdev->kzdev_lock); - kvm_put_kvm(kvm); + kvm_put_kvm_async(kvm); return rc; } @@ -567,7 +567,11 @@ static void kvm_s390_pci_unregister_kvm(void *opaque) mutex_unlock(&kvm->lock); mutex_unlock(&zdev->kzdev_lock); - kvm_put_kvm(kvm); + /* + * Avoid possible deadlock on any currently-held vfio lock by + * ensuring the potential kvm_destroy_vm call is done asynchronously + */ + kvm_put_kvm_async(kvm); } void kvm_s390_pci_init_list(struct kvm *kvm) -- 2.39.0
WARNING: multiple messages have this Message-ID (diff)
From: Matthew Rosato <mjrosato@linux.ibm.com> To: alex.williamson@redhat.com, pbonzini@redhat.com Cc: akrowiak@linux.ibm.com, jjherne@linux.ibm.com, farman@linux.ibm.com, imbrenda@linux.ibm.com, frankja@linux.ibm.com, pmorel@linux.ibm.com, david@redhat.com, linux-s390@vger.kernel.org, intel-gfx@lists.freedesktop.org, cohuck@redhat.com, linux-kernel@vger.kernel.org, pasic@linux.ibm.com, jgg@nvidia.com, kvm@vger.kernel.org, borntraeger@linux.ibm.com, intel-gvt-dev@lists.freedesktop.org Subject: [Intel-gfx] [PATCH 2/2] KVM: s390: pci: use asyncronous kvm put Date: Mon, 9 Jan 2023 15:10:37 -0500 [thread overview] Message-ID: <20230109201037.33051-3-mjrosato@linux.ibm.com> (raw) In-Reply-To: <20230109201037.33051-1-mjrosato@linux.ibm.com> It's possible that the kvm refcount will reach 0 at this point while the associated device is still in kvm device list - this would result in a deadlock on the vfio group lock. Avoid this possibility by using kvm_put_kvm_async to do the kvm_destroy_vm asynchronously. Fixes: 09340b2fca00 ("KVM: s390: pci: add routines to start/stop interpretive execution") Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com> --- arch/s390/kvm/pci.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c index ec51e810e381..d1d528438138 100644 --- a/arch/s390/kvm/pci.c +++ b/arch/s390/kvm/pci.c @@ -509,7 +509,7 @@ static int kvm_s390_pci_register_kvm(void *opaque, struct kvm *kvm) kvm_s390_pci_dev_release(zdev); mutex_unlock(&kvm->lock); mutex_unlock(&zdev->kzdev_lock); - kvm_put_kvm(kvm); + kvm_put_kvm_async(kvm); return rc; } @@ -567,7 +567,11 @@ static void kvm_s390_pci_unregister_kvm(void *opaque) mutex_unlock(&kvm->lock); mutex_unlock(&zdev->kzdev_lock); - kvm_put_kvm(kvm); + /* + * Avoid possible deadlock on any currently-held vfio lock by + * ensuring the potential kvm_destroy_vm call is done asynchronously + */ + kvm_put_kvm_async(kvm); } void kvm_s390_pci_init_list(struct kvm *kvm) -- 2.39.0
next prev parent reply other threads:[~2023-01-09 20:11 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-01-09 20:10 [PATCH 0/2] kvm/vfio: fix potential deadlock on vfio group lock Matthew Rosato 2023-01-09 20:10 ` [Intel-gfx] " Matthew Rosato 2023-01-09 20:10 ` [PATCH 1/2] KVM: async kvm_destroy_vm for vfio devices Matthew Rosato 2023-01-09 20:10 ` [Intel-gfx] " Matthew Rosato 2023-01-09 20:13 ` Jason Gunthorpe 2023-01-09 20:13 ` Jason Gunthorpe 2023-01-09 20:24 ` Matthew Rosato 2023-01-09 20:24 ` [Intel-gfx] " Matthew Rosato 2023-01-09 21:07 ` Anthony Krowiak 2023-01-09 21:07 ` [Intel-gfx] " Anthony Krowiak 2023-01-11 19:54 ` Sean Christopherson 2023-01-11 19:54 ` [Intel-gfx] " Sean Christopherson 2023-01-11 20:05 ` Jason Gunthorpe 2023-01-11 20:05 ` Jason Gunthorpe 2023-01-11 20:53 ` Sean Christopherson 2023-01-11 20:53 ` [Intel-gfx] " Sean Christopherson 2023-01-12 12:45 ` Jason Gunthorpe 2023-01-12 12:45 ` [Intel-gfx] " Jason Gunthorpe 2023-01-12 17:21 ` Matthew Rosato 2023-01-12 17:21 ` Matthew Rosato 2023-01-12 17:27 ` [Intel-gfx] " Jason Gunthorpe 2023-01-12 17:27 ` Jason Gunthorpe 2023-01-09 20:10 ` Matthew Rosato [this message] 2023-01-09 20:10 ` [Intel-gfx] [PATCH 2/2] KVM: s390: pci: use asyncronous kvm put Matthew Rosato 2023-01-09 21:10 ` [Intel-gfx] ✗ Fi.CI.SPARSE: warning for kvm/vfio: fix potential deadlock on vfio group lock Patchwork 2023-01-09 21:38 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork 2023-01-10 7:08 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork 2023-01-11 20:39 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for kvm/vfio: fix potential deadlock on vfio group lock (rev2) Patchwork 2023-01-11 21:09 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for kvm/vfio: fix potential deadlock on vfio group lock (rev3) Patchwork 2023-01-12 19:32 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for kvm/vfio: fix potential deadlock on vfio group lock (rev4) Patchwork
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