[RFC PATCH v2 05/10] iommu/riscv: support GSCID and GVMA invalidation command

[Zong Li]

This patch adds a ID Allocator for GSCID and a wrap for setting up
GSCID in IOTLB invalidation command.

Set up iohgatp to enable second stage table and flush stage-2 table if
the GSCID is set.

The GSCID of domain should be freed when release domain. GSCID will be
allocated for parent domain in nested IOMMU process.

Signed-off-by: Zong Li <zong.li@xxxxxxxxxx>
---
 drivers/iommu/riscv/iommu-bits.h |  7 ++++++
 drivers/iommu/riscv/iommu.c      | 39 ++++++++++++++++++++++++++++----
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/riscv/iommu-bits.h b/drivers/iommu/riscv/iommu-bits.h
index 60523449f016..214735a335fd 100644
--- a/drivers/iommu/riscv/iommu-bits.h
+++ b/drivers/iommu/riscv/iommu-bits.h
@@ -731,6 +731,13 @@ static inline void riscv_iommu_cmd_inval_vma(struct riscv_iommu_command *cmd)
 	cmd->dword1 = 0;
 }
 
+static inline void riscv_iommu_cmd_inval_gvma(struct riscv_iommu_command *cmd)
+{
+	cmd->dword0 = FIELD_PREP(RISCV_IOMMU_CMD_OPCODE, RISCV_IOMMU_CMD_IOTINVAL_OPCODE) |
+		      FIELD_PREP(RISCV_IOMMU_CMD_FUNC, RISCV_IOMMU_CMD_IOTINVAL_FUNC_GVMA);
+	cmd->dword1 = 0;
+}
+
 static inline void riscv_iommu_cmd_inval_set_addr(struct riscv_iommu_command *cmd,
 						  u64 addr)
 {
diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
index df7aeb2571ae..45309bd096e5 100644
--- a/drivers/iommu/riscv/iommu.c
+++ b/drivers/iommu/riscv/iommu.c
@@ -45,6 +45,10 @@
 static DEFINE_IDA(riscv_iommu_pscids);
 #define RISCV_IOMMU_MAX_PSCID		(BIT(20) - 1)
 
+/* IOMMU GSCID allocation namespace. */
+static DEFINE_IDA(riscv_iommu_gscids);
+#define RISCV_IOMMU_MAX_GSCID		(BIT(16) - 1)
+
 /* Device resource-managed allocations */
 struct riscv_iommu_devres {
 	void *addr;
@@ -845,6 +849,7 @@ struct riscv_iommu_domain {
 	struct list_head bonds;
 	spinlock_t lock;		/* protect bonds list updates. */
 	int pscid;
+	int gscid;
 	int amo_enabled:1;
 	int numa_node;
 	unsigned int pgd_mode;
@@ -993,20 +998,33 @@ static void riscv_iommu_iotlb_inval(struct riscv_iommu_domain *domain,
 	rcu_read_lock();
 
 	prev = NULL;
+
 	list_for_each_entry_rcu(bond, &domain->bonds, list) {
 		iommu = dev_to_iommu(bond->dev);
 
 		/*
 		 * IOTLB invalidation request can be safely omitted if already sent
-		 * to the IOMMU for the same PSCID, and with domain->bonds list
+		 * to the IOMMU for the same PSCID/GSCID, and with domain->bonds list
 		 * arranged based on the device's IOMMU, it's sufficient to check
 		 * last device the invalidation was sent to.
 		 */
 		if (iommu == prev)
 			continue;
 
-		riscv_iommu_cmd_inval_vma(&cmd);
-		riscv_iommu_cmd_inval_set_pscid(&cmd, domain->pscid);
+		/*
+		 * S2 domain needs to flush entries in stage-2 page table, its
+		 * bond list has host devices and pass-through devices, the GVMA
+		 * command is no effect on host devices, because there are no
+		 * mapping of host devices in stage-2 page table.
+		 */
+		if (domain->gscid) {
+			riscv_iommu_cmd_inval_gvma(&cmd);
+			riscv_iommu_cmd_inval_set_gscid(&cmd, domain->gscid);
+		} else {
+			riscv_iommu_cmd_inval_vma(&cmd);
+			riscv_iommu_cmd_inval_set_pscid(&cmd, domain->pscid);
+		}
+
 		if (len && len < RISCV_IOMMU_IOTLB_INVAL_LIMIT) {
 			for (iova = start; iova < end; iova += PAGE_SIZE) {
 				riscv_iommu_cmd_inval_set_addr(&cmd, iova);
@@ -1015,6 +1033,7 @@ static void riscv_iommu_iotlb_inval(struct riscv_iommu_domain *domain,
 		} else {
 			riscv_iommu_cmd_send(iommu, &cmd);
 		}
+
 		prev = iommu;
 	}
 
@@ -1083,6 +1102,7 @@ static void riscv_iommu_iodir_update(struct riscv_iommu_device *iommu,
 
 		WRITE_ONCE(dc->fsc, new_dc->fsc);
 		WRITE_ONCE(dc->ta, new_dc->ta & RISCV_IOMMU_PC_TA_PSCID);
+		WRITE_ONCE(dc->iohgatp, new_dc->iohgatp);
 		/* Update device context, write TC.V as the last step. */
 		dma_wmb();
 		WRITE_ONCE(dc->tc, tc);
@@ -1354,6 +1374,9 @@ static void riscv_iommu_free_paging_domain(struct iommu_domain *iommu_domain)
 	if ((int)domain->pscid > 0)
 		ida_free(&riscv_iommu_pscids, domain->pscid);
 
+	if ((int)domain->gscid > 0)
+		ida_free(&riscv_iommu_gscids, domain->gscid);
+
 	riscv_iommu_pte_free(domain, _io_pte_entry(pfn, _PAGE_TABLE), NULL);
 	kfree(domain);
 }
@@ -1384,8 +1407,14 @@ static int riscv_iommu_attach_paging_domain(struct iommu_domain *iommu_domain,
 	if (!riscv_iommu_pt_supported(iommu, domain->pgd_mode))
 		return -ENODEV;
 
-	dc.fsc = FIELD_PREP(RISCV_IOMMU_PC_FSC_MODE, domain->pgd_mode) |
-		 FIELD_PREP(RISCV_IOMMU_PC_FSC_PPN, virt_to_pfn(domain->pgd_root));
+	if (domain->gscid)
+		dc.iohgatp = FIELD_PREP(RISCV_IOMMU_DC_IOHGATP_MODE, domain->pgd_mode) |
+			     FIELD_PREP(RISCV_IOMMU_DC_IOHGATP_GSCID, domain->gscid) |
+			     FIELD_PREP(RISCV_IOMMU_DC_IOHGATP_PPN, virt_to_pfn(domain->pgd_root));
+	else
+		dc.fsc = FIELD_PREP(RISCV_IOMMU_PC_FSC_MODE, domain->pgd_mode) |
+			 FIELD_PREP(RISCV_IOMMU_PC_FSC_PPN, virt_to_pfn(domain->pgd_root));
+
 	dc.ta = FIELD_PREP(RISCV_IOMMU_PC_TA_PSCID, domain->pscid) |
 			   RISCV_IOMMU_PC_TA_V;
 
-- 
2.17.1