[PATCH v5 12/17] irqchip/riscv-imsic: Support IOMMU MSI address lists

[Andrew Jones]

RISC-V IOMMU host interrupt remapping maps every possible host IMSIC
target into one contiguous IOVA range. MSI message composition therefore
needs each target's position within that range.

When the S-mode IMSIC address list is available, prepare the complete
list while allocating an IRQ. This allows the IOMMU backend to map the
pages and cache the contiguous base IOVA in the MSI descriptor. Skip the
optional preparation when no list is available, allowing devices which
do not need IOMMU MSI translation to keep using physical MSI messages.

When the descriptor has an IOMMU MSI mapping, use the selected logical
CPU directly as the page index within the IOVA range. Use the same path
for initial composition and affinity updates. Messages remain physical
when no IOMMU MSI mapping is required.

Signed-off-by: Andrew Jones <andrew.jones@xxxxxxxxxxxxxxxx>
---
 drivers/irqchip/Kconfig                    |  1 +
 drivers/irqchip/irq-riscv-imsic-platform.c | 25 +++++++++++++++++++---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 42f2278a702d..c7cda52b21eb 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -656,6 +656,7 @@ config RISCV_IMSIC
 	select IRQ_DOMAIN_HIERARCHY
 	select GENERIC_IRQ_MATRIX_ALLOCATOR
 	select GENERIC_MSI_IRQ
+	select IRQ_MSI_IOMMU
 	select IRQ_MSI_LIB
 
 config RISCV_RPMI_SYSMSI
diff --git a/drivers/irqchip/irq-riscv-imsic-platform.c b/drivers/irqchip/irq-riscv-imsic-platform.c
index 643c8e459611..6e26a31f7503 100644
--- a/drivers/irqchip/irq-riscv-imsic-platform.c
+++ b/drivers/irqchip/irq-riscv-imsic-platform.c
@@ -10,6 +10,7 @@
 #include <linux/cpu.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/iommu.h>
 #include <linux/irq.h>
 #include <linux/irqchip.h>
 #include <linux/irqdomain.h>
@@ -69,8 +70,10 @@ static void imsic_irq_ack(struct irq_data *d)
 	irq_move_irq(d);
 }
 
-static void imsic_irq_compose_vector_msg(struct imsic_vector *vec, struct msi_msg *msg)
+static void imsic_irq_compose_vector_msg(struct irq_data *d, struct imsic_vector *vec,
+					 struct msi_msg *msg)
 {
+	struct msi_desc *desc = irq_data_get_msi_desc(d);
 	phys_addr_t msi_addr;
 
 	if (WARN_ON(!vec))
@@ -79,6 +82,11 @@ static void imsic_irq_compose_vector_msg(struct imsic_vector *vec, struct msi_ms
 	if (WARN_ON(!imsic_cpu_page_phys(vec->cpu, 0, &msi_addr)))
 		return;
 
+	if (desc->iommu_msi_shift) {
+		msi_addr = (desc->iommu_msi_iova << desc->iommu_msi_shift) +
+			   vec->cpu * IMSIC_MMIO_PAGE_SZ;
+	}
+
 	msg->address_hi = upper_32_bits(msi_addr);
 	msg->address_lo = lower_32_bits(msi_addr);
 	msg->data = vec->local_id;
@@ -86,7 +94,7 @@ static void imsic_irq_compose_vector_msg(struct imsic_vector *vec, struct msi_ms
 
 static void imsic_irq_compose_msg(struct irq_data *d, struct msi_msg *msg)
 {
-	imsic_irq_compose_vector_msg(irq_data_get_irq_chip_data(d), msg);
+	imsic_irq_compose_vector_msg(d, irq_data_get_irq_chip_data(d), msg);
 }
 
 #ifdef CONFIG_SMP
@@ -94,7 +102,7 @@ static void imsic_msi_update_msg(struct irq_data *d, struct imsic_vector *vec)
 {
 	struct msi_msg msg = { };
 
-	imsic_irq_compose_vector_msg(vec, &msg);
+	imsic_irq_compose_vector_msg(d, vec, &msg);
 	irq_data_get_irq_chip(d)->irq_write_msi_msg(d, &msg);
 }
 
@@ -225,7 +233,9 @@ static struct irq_chip imsic_irq_base_chip = {
 static int imsic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 				  unsigned int nr_irqs, void *args)
 {
+	msi_alloc_info_t *info = args;
 	struct imsic_vector *vec;
+	int ret;
 
 	/* Multi-MSI is not supported yet. */
 	if (nr_irqs > 1)
@@ -235,6 +245,15 @@ static int imsic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
 	if (!vec)
 		return -ENOSPC;
 
+	if (imsic->smode_msi_pa) {
+		ret = iommu_dma_prepare_msi_list(info->desc, imsic->smode_msi_pa,
+						 num_possible_cpus(), IMSIC_MMIO_PAGE_SZ);
+		if (ret) {
+			imsic_vector_free(vec);
+			return ret;
+		}
+	}
+
 	irq_domain_set_info(domain, virq, virq, &imsic_irq_base_chip, vec,
 			    handle_edge_irq, NULL, NULL);
 	irq_set_noprobe(virq);
-- 
2.43.0