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| author | Oliver Upton <oliver.upton@linux.dev> | 2024-02-21 05:42:51 +0000 |
|---|---|---|
| committer | Oliver Upton <oliver.upton@linux.dev> | 2024-02-23 21:46:02 +0000 |
| commit | 864d4304ec1e67b8235e2aae5d31bdad6dd8aa7c (patch) | |
| tree | bf55aa60dc6826a50e069e30a4f0453799441bed /arch/arm64 | |
| parent | a5c7f011cb584a4713b3defc533ed55e237210a4 (diff) | |
| download | linux-stable-864d4304ec1e67b8235e2aae5d31bdad6dd8aa7c.tar.gz linux-stable-864d4304ec1e67b8235e2aae5d31bdad6dd8aa7c.tar.bz2 linux-stable-864d4304ec1e67b8235e2aae5d31bdad6dd8aa7c.zip | |
KVM: arm64: vgic: Rely on RCU protection in vgic_get_lpi()
Stop acquiring the lpi_list_lock in favor of RCU for protecting
the read-side critical section in vgic_get_lpi(). In order for this to
be safe, we also need to be careful not to take a reference on an irq
with a refcount of 0, as it is about to be freed.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240221054253.3848076-9-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/kvm/vgic/vgic.c | 9 | ||||
| -rw-r--r-- | arch/arm64/kvm/vgic/vgic.h | 14 |
2 files changed, 15 insertions, 8 deletions
diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c index 3fedc58e663a..76abf3d946fe 100644 --- a/arch/arm64/kvm/vgic/vgic.c +++ b/arch/arm64/kvm/vgic/vgic.c @@ -63,15 +63,14 @@ static struct vgic_irq *vgic_get_lpi(struct kvm *kvm, u32 intid) { struct vgic_dist *dist = &kvm->arch.vgic; struct vgic_irq *irq = NULL; - unsigned long flags; - raw_spin_lock_irqsave(&dist->lpi_list_lock, flags); + rcu_read_lock(); irq = xa_load(&dist->lpi_xa, intid); - if (irq) - vgic_get_irq_kref(irq); + if (!vgic_try_get_irq_kref(irq)) + irq = NULL; - raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags); + rcu_read_unlock(); return irq; } diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h index 8d134569d0a1..f874b9932c5a 100644 --- a/arch/arm64/kvm/vgic/vgic.h +++ b/arch/arm64/kvm/vgic/vgic.h @@ -220,12 +220,20 @@ void vgic_v2_vmcr_sync(struct kvm_vcpu *vcpu); void vgic_v2_save_state(struct kvm_vcpu *vcpu); void vgic_v2_restore_state(struct kvm_vcpu *vcpu); -static inline void vgic_get_irq_kref(struct vgic_irq *irq) +static inline bool vgic_try_get_irq_kref(struct vgic_irq *irq) { + if (!irq) + return false; + if (irq->intid < VGIC_MIN_LPI) - return; + return true; - kref_get(&irq->refcount); + return kref_get_unless_zero(&irq->refcount); +} + +static inline void vgic_get_irq_kref(struct vgic_irq *irq) +{ + WARN_ON_ONCE(!vgic_try_get_irq_kref(irq)); } void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu); |