linux-kernel - [RFC][PATCH v2 08/13] iommu/arm-smmu-v3: Add VMID alloc/free helpers

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Message-ID: <20210831025923.15812-9-nicolinc@nvidia.com>
Date:   Mon, 30 Aug 2021 19:59:18 -0700
From:   Nicolin Chen <nicolinc@...dia.com>
To:     <will@...nel.org>, <robin.murphy@....com>, <joro@...tes.org>,
        <alex.williamson@...hat.com>, <cohuck@...hat.com>, <corbet@....net>
CC:     <nicoleotsuka@...il.com>, <vdumpa@...dia.com>,
        <thierry.reding@...il.com>, <linux-tegra@...r.kernel.org>,
        <nwatterson@...dia.com>, <Jonathan.Cameron@...wei.com>,
        <jean-philippe@...aro.org>, <song.bao.hua@...ilicon.com>,
        <eric.auger@...hat.com>, <thunder.leizhen@...wei.com>,
        <yuzenghui@...wei.com>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <iommu@...ts.linux-foundation.org>, <kvm@...r.kernel.org>,
        <linux-doc@...r.kernel.org>
Subject: [RFC][PATCH v2 08/13] iommu/arm-smmu-v3: Add VMID alloc/free helpers

NVIDIA implementation needs to link its Virtual Interface to a
VMID, before a device gets attached to the corresponding iommu
domain. One way to ensure that is to allocate a VMID from impl
side and to pass it down to virtual machine hypervisor so that
later it can set it back to passthrough devices' iommu domains
calling newly added arm_smmu_set/get_nesting_vmid() functions.

This patch adds a pair of helpers to allocate and free VMID in
the bitmap.

Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 10 ++++++++++
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index c0ae117711fa..497d55ec659b 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2032,6 +2032,16 @@ static void arm_smmu_bitmap_free(unsigned long *map, int idx)
 	clear_bit(idx, map);
 }
 
+int arm_smmu_vmid_alloc(struct arm_smmu_device *smmu)
+{
+	return arm_smmu_bitmap_alloc(smmu->vmid_map, smmu->vmid_bits);
+}
+
+void arm_smmu_vmid_free(struct arm_smmu_device *smmu, u16 vmid)
+{
+	arm_smmu_bitmap_free(smmu->vmid_map, vmid);
+}
+
 static void arm_smmu_domain_free(struct iommu_domain *domain)
 {
 	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index ea2c61d52df8..20463d17fd9f 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -749,6 +749,9 @@ bool arm_smmu_free_asid(struct arm_smmu_ctx_desc *cd);
 int arm_smmu_atc_inv_domain(struct arm_smmu_domain *smmu_domain, int ssid,
 			    unsigned long iova, size_t size);
 
+int arm_smmu_vmid_alloc(struct arm_smmu_device *smmu);
+void arm_smmu_vmid_free(struct arm_smmu_device *smmu, u16 vmid);
+
 #ifdef CONFIG_ARM_SMMU_V3_SVA
 bool arm_smmu_sva_supported(struct arm_smmu_device *smmu);
 bool arm_smmu_master_sva_supported(struct arm_smmu_master *master);
-- 
2.17.1