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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1707816805; 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=nQ22xtb57Hhh6ukA9UKpHbyaiDwLVQOEd0N6U2bxudQ=; b=lQLrteem+/oNETa88tCfy93s3hWpOQjhHY9udjC6jjluC/ugre068aS/g+cCHk38wmFIsT llzxysWLqD6W5XXtdWNc3eO5DfxFGCce105uksr2XMisqueJ+4opUXNBfUW4IqJp1zCYUn AluLUWq2PU2m0JaY0lo+9urNUaCPJVg= From: Oliver Upton To: kvmarm@lists.linux.dev Cc: kvm@vger.kernel.org, Marc Zyngier , James Morse , Suzuki K Poulose , Zenghui Yu , linux-kernel@vger.kernel.org, Oliver Upton Subject: [PATCH v2 07/23] KVM: arm64: vgic: Use atomics to count LPIs Date: Tue, 13 Feb 2024 09:32:44 +0000 Message-ID: <20240213093250.3960069-8-oliver.upton@linux.dev> In-Reply-To: <20240213093250.3960069-1-oliver.upton@linux.dev> References: <20240213093250.3960069-1-oliver.upton@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1790776368403555513 X-GMAIL-MSGID: 1790776368403555513 Switch to using atomics for LPI accounting, allowing vgic_irq references to be dropped in parallel. Signed-off-by: Oliver Upton --- arch/arm64/kvm/vgic/vgic-debug.c | 2 +- arch/arm64/kvm/vgic/vgic-its.c | 4 ++-- arch/arm64/kvm/vgic/vgic.c | 2 +- include/kvm/arm_vgic.h | 4 ++-- 4 files changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/arm64/kvm/vgic/vgic-debug.c b/arch/arm64/kvm/vgic/vgic-debug.c index 85606a531dc3..389025ce7749 100644 --- a/arch/arm64/kvm/vgic/vgic-debug.c +++ b/arch/arm64/kvm/vgic/vgic-debug.c @@ -149,7 +149,7 @@ static void print_dist_state(struct seq_file *s, struct vgic_dist *dist) seq_printf(s, "vgic_model:\t%s\n", v3 ? "GICv3" : "GICv2"); seq_printf(s, "nr_spis:\t%d\n", dist->nr_spis); if (v3) - seq_printf(s, "nr_lpis:\t%d\n", dist->lpi_list_count); + seq_printf(s, "nr_lpis:\t%d\n", atomic_read(&dist->lpi_count)); seq_printf(s, "enabled:\t%d\n", dist->enabled); seq_printf(s, "\n"); diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c index c68164d6cba0..048226812974 100644 --- a/arch/arm64/kvm/vgic/vgic-its.c +++ b/arch/arm64/kvm/vgic/vgic-its.c @@ -97,7 +97,7 @@ static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid, goto out_unlock; } - dist->lpi_list_count++; + atomic_inc(&dist->lpi_count); out_unlock: if (ret) @@ -345,7 +345,7 @@ int vgic_copy_lpi_list(struct kvm *kvm, struct kvm_vcpu *vcpu, u32 **intid_ptr) * command). If coming from another path (such as enabling LPIs), * we must be careful not to overrun the array. */ - irq_count = READ_ONCE(dist->lpi_list_count); + irq_count = atomic_read(&dist->lpi_count); intids = kmalloc_array(irq_count, sizeof(intids[0]), GFP_KERNEL_ACCOUNT); if (!intids) return -ENOMEM; diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c index e58ce68e325c..5988d162b765 100644 --- a/arch/arm64/kvm/vgic/vgic.c +++ b/arch/arm64/kvm/vgic/vgic.c @@ -122,7 +122,7 @@ void __vgic_put_lpi_locked(struct kvm *kvm, struct vgic_irq *irq) return; xa_erase(&dist->lpi_xa, irq->intid); - dist->lpi_list_count--; + atomic_dec(&dist->lpi_count); kfree(irq); } diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h index aeff363e3ba6..71e9d719533b 100644 --- a/include/kvm/arm_vgic.h +++ b/include/kvm/arm_vgic.h @@ -273,10 +273,10 @@ struct vgic_dist { */ u64 propbaser; - /* Protects the lpi_list and the count value below. */ + /* Protects the lpi_list. */ raw_spinlock_t lpi_list_lock; struct xarray lpi_xa; - int lpi_list_count; + atomic_t lpi_count; /* LPI translation cache */ struct list_head lpi_translation_cache;