From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-178.mta0.migadu.com (out-178.mta0.migadu.com [91.218.175.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 57C7536CDE2 for ; Fri, 5 Sep 2025 14:21:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757082108; cv=none; b=MNJugDmaz+KdLkGXBvhNHmqv9o2LlMKUOHHGqiWvumTJcxLPK2aXdxZVxHJzRufo0uqijxedSx0mQerOQGp7nwgHOCFWZ4dddI8GmGLMLBCmNo7aJ2w75F6fgF4DZjCM3fafKeiUOlxth38oRL6imAjZWP98RarVAUuTNk2KTA0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757082108; c=relaxed/simple; bh=itH2t9Dt98btkK1FY/U2bRt/1RKr8iL1XgCSYUUs/LQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=APd4xcp4DNSuyxfNPWfCiKj7N5Hw/k9axUS2kUU9j59Yylc4TuSUU0PSy64HoaJpcGJkKV3xFsX8vwU4C2CM6Wmsf8Nn4bSCWHz+7VoQPdzk1VXBcZiN7NgKsrfXUPIs+uNM0edkE7CB3GL+VcKyDKDEywioLff6hHm1c+aVwKo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=fHtG0TDB; arc=none smtp.client-ip=91.218.175.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="fHtG0TDB" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1757082104; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Du8gM+N3TDR07nEI1SGzyN1zwWbXyK58nfBTIt/fRJI=; b=fHtG0TDB0veLVIbHj3MibQA1LIaUwqfg4zt9P2eNw5W5A5rrvy2pXzoBMYtSyN5i4svSJr 2mphqYLLm3G92FKNN/uBLBdCcW2m+aBHfjSkP7hitm60C3v4Q13g3kgYYg0xD4FtcS5uUs nY2QcZ4eJTKk8+4dphlNpkWWNgp1F/I= From: Oliver Upton To: kvmarm@lists.linux.dev Cc: Marc Zyngier , Joey Gouly , Suzuki K Poulose , Zenghui Yu , Ben Horgan , Oliver Upton Subject: [PATCH v2 2/6] KVM: arm64: vgic-v3: Use bare refcount for VGIC LPIs Date: Fri, 5 Sep 2025 03:05:27 -0700 Message-Id: <20250905100531.282980-3-oliver.upton@linux.dev> In-Reply-To: <20250905100531.282980-1-oliver.upton@linux.dev> References: <20250905100531.282980-1-oliver.upton@linux.dev> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT KVM's use of krefs to manage LPIs isn't adding much, especially considering vgic_irq_release() is a noop due to the lack of sufficient context. Switch to using a regular refcount in anticipation of adding a meaningful release concept for LPIs. Reviewed-by: Marc Zyngier Signed-off-by: Oliver Upton --- arch/arm64/kvm/vgic/vgic-debug.c | 2 +- arch/arm64/kvm/vgic/vgic-init.c | 4 ++-- arch/arm64/kvm/vgic/vgic-its.c | 8 ++++---- arch/arm64/kvm/vgic/vgic-v4.c | 2 +- arch/arm64/kvm/vgic/vgic.c | 17 ++++------------- arch/arm64/kvm/vgic/vgic.h | 8 ++++---- include/kvm/arm_vgic.h | 4 ++-- 7 files changed, 18 insertions(+), 27 deletions(-) diff --git a/arch/arm64/kvm/vgic/vgic-debug.c b/arch/arm64/kvm/vgic/vgic-debug.c index 2684f273d9e1..4c1209261b65 100644 --- a/arch/arm64/kvm/vgic/vgic-debug.c +++ b/arch/arm64/kvm/vgic/vgic-debug.c @@ -69,7 +69,7 @@ static int iter_mark_lpis(struct kvm *kvm) int nr_lpis = 0; xa_for_each(&dist->lpi_xa, intid, irq) { - if (!vgic_try_get_irq_kref(irq)) + if (!vgic_try_get_irq_ref(irq)) continue; xa_set_mark(&dist->lpi_xa, intid, LPI_XA_MARK_DEBUG_ITER); diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c index 1e680ad6e863..4c777136ea5f 100644 --- a/arch/arm64/kvm/vgic/vgic-init.c +++ b/arch/arm64/kvm/vgic/vgic-init.c @@ -208,7 +208,7 @@ static int kvm_vgic_dist_init(struct kvm *kvm, unsigned int nr_spis) raw_spin_lock_init(&irq->irq_lock); irq->vcpu = NULL; irq->target_vcpu = vcpu0; - kref_init(&irq->refcount); + refcount_set(&irq->refcount, 0); switch (dist->vgic_model) { case KVM_DEV_TYPE_ARM_VGIC_V2: irq->targets = 0; @@ -277,7 +277,7 @@ static int vgic_allocate_private_irqs_locked(struct kvm_vcpu *vcpu, u32 type) irq->intid = i; irq->vcpu = NULL; irq->target_vcpu = vcpu; - kref_init(&irq->refcount); + refcount_set(&irq->refcount, 0); if (vgic_irq_is_sgi(i)) { /* SGIs */ irq->enabled = 1; diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c index 7368c13f16b7..f162206adb48 100644 --- a/arch/arm64/kvm/vgic/vgic-its.c +++ b/arch/arm64/kvm/vgic/vgic-its.c @@ -99,7 +99,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid, raw_spin_lock_init(&irq->irq_lock); irq->config = VGIC_CONFIG_EDGE; - kref_init(&irq->refcount); + refcount_set(&irq->refcount, 1); irq->intid = intid; irq->target_vcpu = vcpu; irq->group = 1; @@ -111,7 +111,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid, * check that we don't add a second list entry with the same LPI. */ oldirq = xa_load(&dist->lpi_xa, intid); - if (vgic_try_get_irq_kref(oldirq)) { + if (vgic_try_get_irq_ref(oldirq)) { /* Someone was faster with adding this LPI, lets use that. */ kfree(irq); irq = oldirq; @@ -547,7 +547,7 @@ static struct vgic_irq *vgic_its_check_cache(struct kvm *kvm, phys_addr_t db, rcu_read_lock(); irq = xa_load(&its->translation_cache, cache_key); - if (!vgic_try_get_irq_kref(irq)) + if (!vgic_try_get_irq_ref(irq)) irq = NULL; rcu_read_unlock(); @@ -571,7 +571,7 @@ static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its, * its_lock, as the ITE (and the reference it holds) cannot be freed. */ lockdep_assert_held(&its->its_lock); - vgic_get_irq_kref(irq); + vgic_get_irq_ref(irq); old = xa_store(&its->translation_cache, cache_key, irq, GFP_KERNEL_ACCOUNT); diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c index 4d9343d2b0b1..548aec9d5a72 100644 --- a/arch/arm64/kvm/vgic/vgic-v4.c +++ b/arch/arm64/kvm/vgic/vgic-v4.c @@ -518,7 +518,7 @@ static struct vgic_irq *__vgic_host_irq_get_vlpi(struct kvm *kvm, int host_irq) if (!irq->hw || irq->host_irq != host_irq) continue; - if (!vgic_try_get_irq_kref(irq)) + if (!vgic_try_get_irq_ref(irq)) return NULL; return irq; diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c index f5148b38120a..a1d6fab895c4 100644 --- a/arch/arm64/kvm/vgic/vgic.c +++ b/arch/arm64/kvm/vgic/vgic.c @@ -71,7 +71,7 @@ static struct vgic_irq *vgic_get_lpi(struct kvm *kvm, u32 intid) rcu_read_lock(); irq = xa_load(&dist->lpi_xa, intid); - if (!vgic_try_get_irq_kref(irq)) + if (!vgic_try_get_irq_ref(irq)) irq = NULL; rcu_read_unlock(); @@ -114,15 +114,6 @@ struct vgic_irq *vgic_get_vcpu_irq(struct kvm_vcpu *vcpu, u32 intid) return vgic_get_irq(vcpu->kvm, intid); } -/* - * We can't do anything in here, because we lack the kvm pointer to - * lock and remove the item from the lpi_list. So we keep this function - * empty and use the return value of kref_put() to trigger the freeing. - */ -static void vgic_irq_release(struct kref *ref) -{ -} - void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq) { struct vgic_dist *dist = &kvm->arch.vgic; @@ -131,7 +122,7 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq) if (irq->intid < VGIC_MIN_LPI) return; - if (!kref_put(&irq->refcount, vgic_irq_release)) + if (!refcount_dec_and_test(&irq->refcount)) return; xa_lock_irqsave(&dist->lpi_xa, flags); @@ -399,7 +390,7 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq, * now in the ap_list. This is safe as the caller must already hold a * reference on the irq. */ - vgic_get_irq_kref(irq); + vgic_get_irq_ref(irq); list_add_tail(&irq->ap_list, &vcpu->arch.vgic_cpu.ap_list_head); irq->vcpu = vcpu; @@ -657,7 +648,7 @@ static void vgic_prune_ap_list(struct kvm_vcpu *vcpu) /* * This vgic_put_irq call matches the - * vgic_get_irq_kref in vgic_queue_irq_unlock, + * vgic_get_irq_ref in vgic_queue_irq_unlock, * where we added the LPI to the ap_list. As * we remove the irq from the list, we drop * also drop the refcount. diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h index de1c1d3261c3..ac5f9c5d2b98 100644 --- a/arch/arm64/kvm/vgic/vgic.h +++ b/arch/arm64/kvm/vgic/vgic.h @@ -267,7 +267,7 @@ void vgic_v2_put(struct kvm_vcpu *vcpu); void vgic_v2_save_state(struct kvm_vcpu *vcpu); void vgic_v2_restore_state(struct kvm_vcpu *vcpu); -static inline bool vgic_try_get_irq_kref(struct vgic_irq *irq) +static inline bool vgic_try_get_irq_ref(struct vgic_irq *irq) { if (!irq) return false; @@ -275,12 +275,12 @@ static inline bool vgic_try_get_irq_kref(struct vgic_irq *irq) if (irq->intid < VGIC_MIN_LPI) return true; - return kref_get_unless_zero(&irq->refcount); + return refcount_inc_not_zero(&irq->refcount); } -static inline void vgic_get_irq_kref(struct vgic_irq *irq) +static inline void vgic_get_irq_ref(struct vgic_irq *irq) { - WARN_ON_ONCE(!vgic_try_get_irq_kref(irq)); + WARN_ON_ONCE(!vgic_try_get_irq_ref(irq)); } void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu); diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h index 9f8a116925ca..640555ff5b54 100644 --- a/include/kvm/arm_vgic.h +++ b/include/kvm/arm_vgic.h @@ -8,8 +8,8 @@ #include #include #include -#include #include +#include #include #include #include @@ -142,7 +142,7 @@ struct vgic_irq { bool active; bool enabled; bool hw; /* Tied to HW IRQ */ - struct kref refcount; /* Used for LPIs */ + refcount_t refcount; /* Used for LPIs */ u32 hwintid; /* HW INTID number */ unsigned int host_irq; /* linux irq corresponding to hwintid */ union { -- 2.39.5