[PATCH v4 13/22] iommu/vt-d: Enlightened PASID allocation

[Jacob Pan]

From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

If Intel IOMMU runs in caching mode, a.k.a. virtual IOMMU, the
IOMMU driver should rely on the emulation software to allocate
and free PASID IDs. The Intel vt-d spec revision 3.0 defines a
register set to support this. This includes a capability register,
a virtual command register and a virtual response register. Refer
to section 10.4.42, 10.4.43, 10.4.44 for more information.

This patch adds the enlightened PASID allocation/free interfaces
via the virtual command register.

Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
 drivers/iommu/intel-pasid.c | 76 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/iommu/intel-pasid.h | 13 +++++++-
 include/linux/intel-iommu.h |  2 ++
 3 files changed, 90 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
index 2fefeaf..69fddd3 100644
--- a/drivers/iommu/intel-pasid.c
+++ b/drivers/iommu/intel-pasid.c
@@ -63,6 +63,82 @@ void *intel_pasid_lookup_id(int pasid)
 	return p;
 }
 
+int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned int *pasid)
+{
+	u64 res;
+	u64 cap;
+	u8 status_code;
+	unsigned long flags;
+	int ret = 0;
+
+	if (!ecap_vcs(iommu->ecap)) {
+		pr_warn("IOMMU: %s: Hardware doesn't support virtual command\n",
+			iommu->name);
+		return -ENODEV;
+	}
+
+	cap = dmar_readq(iommu->reg + DMAR_VCCAP_REG);
+	if (!(cap & DMA_VCS_PAS)) {
+		pr_warn("IOMMU: %s: Emulation software doesn't support PASID allocation\n",
+			iommu->name);
+		return -ENODEV;
+	}
+
+	raw_spin_lock_irqsave(&iommu->register_lock, flags);
+	dmar_writeq(iommu->reg + DMAR_VCMD_REG, VCMD_CMD_ALLOC);
+	IOMMU_WAIT_OP(iommu, DMAR_VCRSP_REG, dmar_readq,
+		      !(res & VCMD_VRSP_IP), res);
+	raw_spin_unlock_irqrestore(&iommu->register_lock, flags);
+
+	status_code = VCMD_VRSP_SC(res);
+	switch (status_code) {
+	case VCMD_VRSP_SC_SUCCESS:
+		*pasid = VCMD_VRSP_RESULT(res);
+		break;
+	case VCMD_VRSP_SC_NO_PASID_AVAIL:
+		pr_info("IOMMU: %s: No PASID available\n", iommu->name);
+		ret = -ENOMEM;
+		break;
+	default:
+		ret = -ENODEV;
+		pr_warn("IOMMU: %s: Unkonwn error code %d\n",
+			iommu->name, status_code);
+	}
+
+	return ret;
+}
+
+void vcmd_free_pasid(struct intel_iommu *iommu, unsigned int pasid)
+{
+	u64 res;
+	u8 status_code;
+	unsigned long flags;
+
+	if (!ecap_vcs(iommu->ecap)) {
+		pr_warn("IOMMU: %s: Hardware doesn't support virtual command\n",
+			iommu->name);
+		return;
+	}
+
+	raw_spin_lock_irqsave(&iommu->register_lock, flags);
+	dmar_writeq(iommu->reg + DMAR_VCMD_REG, (pasid << 8) | VCMD_CMD_FREE);
+	IOMMU_WAIT_OP(iommu, DMAR_VCRSP_REG, dmar_readq,
+		      !(res & VCMD_VRSP_IP), res);
+	raw_spin_unlock_irqrestore(&iommu->register_lock, flags);
+
+	status_code = VCMD_VRSP_SC(res);
+	switch (status_code) {
+	case VCMD_VRSP_SC_SUCCESS:
+		break;
+	case VCMD_VRSP_SC_INVALID_PASID:
+		pr_info("IOMMU: %s: Invalid PASID\n", iommu->name);
+		break;
+	default:
+		pr_warn("IOMMU: %s: Unkonwn error code %d\n",
+			iommu->name, status_code);
+	}
+}
+
 /*
  * Per device pasid table management:
  */
diff --git a/drivers/iommu/intel-pasid.h b/drivers/iommu/intel-pasid.h
index 23537b3..4b26ab5 100644
--- a/drivers/iommu/intel-pasid.h
+++ b/drivers/iommu/intel-pasid.h
@@ -19,6 +19,16 @@
 #define PASID_PDE_SHIFT			6
 #define MAX_NR_PASID_BITS		20
 
+/* Virtual command interface for enlightened pasid management. */
+#define VCMD_CMD_ALLOC			0x1
+#define VCMD_CMD_FREE			0x2
+#define VCMD_VRSP_IP			0x1
+#define VCMD_VRSP_SC(e)			(((e) >> 1) & 0x3)
+#define VCMD_VRSP_SC_SUCCESS		0
+#define VCMD_VRSP_SC_NO_PASID_AVAIL	1
+#define VCMD_VRSP_SC_INVALID_PASID	1
+#define VCMD_VRSP_RESULT(e)		(((e) >> 8) & 0xfffff)
+
 /*
  * Domain ID reserved for pasid entries programmed for first-level
  * only and pass-through transfer modes.
@@ -69,5 +79,6 @@ int intel_pasid_setup_pass_through(struct intel_iommu *iommu,
 				   struct device *dev, int pasid);
 void intel_pasid_tear_down_entry(struct intel_iommu *iommu,
 				 struct device *dev, int pasid);
-
+int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned int *pasid);
+void vcmd_free_pasid(struct intel_iommu *iommu, unsigned int pasid);
 #endif /* __INTEL_PASID_H */
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 6925a18..bff907b 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -173,6 +173,7 @@
 #define ecap_smpwc(e)		(((e) >> 48) & 0x1)
 #define ecap_flts(e)		(((e) >> 47) & 0x1)
 #define ecap_slts(e)		(((e) >> 46) & 0x1)
+#define ecap_vcs(e)		(((e) >> 44) & 0x1)
 #define ecap_smts(e)		(((e) >> 43) & 0x1)
 #define ecap_dit(e)		((e >> 41) & 0x1)
 #define ecap_pasid(e)		((e >> 40) & 0x1)
@@ -289,6 +290,7 @@
 
 /* PRS_REG */
 #define DMA_PRS_PPR	((u32)1)
+#define DMA_VCS_PAS	((u64)1)
 
 #define IOMMU_WAIT_OP(iommu, offset, op, cond, sts)			\
 do {									\
-- 
2.7.4