[PATCH v8 07/10] iommu/vt-d: Enlightened PASID allocation

[Jacob Pan]

From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Enabling IOMMU in a guest requires communication with the host
driver for certain aspects. Use of PASID ID to enable Shared Virtual
Addressing (SVA) requires managing PASID's in the host. VT-d 3.0 spec
provides a Virtual Command Register (VCMD) to facilitate this.
Writes to this register in the guest are trapped by QEMU which
proxies the call to the host driver.

This virtual command interface consists of 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 interface.

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>
Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
---
 drivers/iommu/intel-pasid.c | 57 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/iommu/intel-pasid.h | 13 ++++++++++-
 include/linux/intel-iommu.h |  2 ++
 3 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
index 10f8c7564118..0a135a5937f3 100644
--- a/drivers/iommu/intel-pasid.c
+++ b/drivers/iommu/intel-pasid.c
@@ -27,6 +27,63 @@
 static DEFINE_SPINLOCK(pasid_lock);
 u32 intel_pasid_max_id = PASID_MAX;
 
+int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned int *pasid)
+{
+	unsigned long flags;
+	u8 status_code;
+	int ret = 0;
+	u64 res;
+
+	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_PASID(res);
+		break;
+	case VCMD_VRSP_SC_NO_PASID_AVAIL:
+		pr_info("IOMMU: %s: No PASID available\n", iommu->name);
+		ret = -ENOSPC;
+		break;
+	default:
+		ret = -ENODEV;
+		pr_warn("IOMMU: %s: Unexpected error code %d\n",
+			iommu->name, status_code);
+	}
+
+	return ret;
+}
+
+void vcmd_free_pasid(struct intel_iommu *iommu, unsigned int pasid)
+{
+	unsigned long flags;
+	u8 status_code;
+	u64 res;
+
+	raw_spin_lock_irqsave(&iommu->register_lock, flags);
+	dmar_writeq(iommu->reg + DMAR_VCMD_REG,
+		    VCMD_CMD_OPERAND(pasid) | 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: Unexpected 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 95ed160b1947..b4c8aece979f 100644
--- a/drivers/iommu/intel-pasid.h
+++ b/drivers/iommu/intel-pasid.h
@@ -23,6 +23,16 @@
 #define is_pasid_enabled(entry)		(((entry)->lo >> 3) & 0x1)
 #define get_pasid_dir_size(entry)	(1 << ((((entry)->lo >> 9) & 0x7) + 7))
 
+/* 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_PASID(e)	(((e) >> 8) & 0xfffff)
+#define VCMD_CMD_OPERAND(e)		((e) << 8)
 /*
  * Domain ID reserved for pasid entries programmed for first-level
  * only and pass-through transfer modes.
@@ -107,5 +117,6 @@ int intel_pasid_setup_nested(struct intel_iommu *iommu,
 			int addr_width);
 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 4d25141ec3df..1e11560b0e59 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -164,6 +164,7 @@
 #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)
@@ -285,6 +286,7 @@
 
 /* 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