[RFC PATCH 12/15] iommu/riscv: Add guest file irqbypass support

Andrew Jones
2024-11-14T16:19:09Z

Implement irq_set_vcpu_affinity() in the RISCV IOMMU driver.
irq_set_vcpu_affinity() is the channel from a hypervisor to the
IOMMU needed to ensure that assigned devices which direct MSIs to
guest IMSIC addresses will have those MSI writes redirected to
their corresponding guest interrupt files.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
---
drivers/iommu/riscv/iommu-ir.c | 151 +++++++++++++++++++++++++++++++++
drivers/iommu/riscv/iommu.c | 4 +-
drivers/iommu/riscv/iommu.h | 3 +
3 files changed, 156 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/riscv/iommu-ir.c b/drivers/iommu/riscv/iommu-ir.c
index c177e064b205..958270450ec1 100644
--- a/drivers/iommu/riscv/iommu-ir.c
+++ b/drivers/iommu/riscv/iommu-ir.c
@@ -7,6 +7,8 @@
#include <linux/irqdomain.h>
#include <linux/msi.h>

+#include <asm/irq.h>
+
#include "../iommu-pages.h"
#include "iommu.h"

@@ -52,10 +54,159 @@ static size_t riscv_iommu_ir_nr_msiptes(struct riscv_iommu_domain *domain)
return max_idx + 1;
}

+static void riscv_iommu_ir_msitbl_inval(struct riscv_iommu_domain *domain,
+ struct riscv_iommu_msipte *pte)
+{
+ struct riscv_iommu_bond *bond;
+ struct riscv_iommu_device *iommu, *prev;
+ struct riscv_iommu_command cmd;
+ u64 addr;
+
+ addr = pfn_to_phys(FIELD_GET(RISCV_IOMMU_MSIPTE_PPN, pte->pte));
+ riscv_iommu_cmd_inval_gvma(&cmd);
+ riscv_iommu_cmd_inval_set_addr(&cmd, addr);
+
+ /* Like riscv_iommu_iotlb_inval(), synchronize with riscv_iommu_bond_link() */
+ smp_mb();
+
+ rcu_read_lock();
+
+ prev = NULL;
+ list_for_each_entry_rcu(bond, &domain->bonds, list) {
+ iommu = dev_to_iommu(bond->dev);
+
+ if (iommu == prev)
+ continue;
+
+ riscv_iommu_cmd_send(iommu, &cmd);
+ riscv_iommu_cmd_sync(iommu, RISCV_IOMMU_IOTINVAL_TIMEOUT);
+ prev = iommu;
+ }
+
+ rcu_read_unlock();
+}
+
+static void riscv_iommu_ir_msitbl_update(struct riscv_iommu_domain *domain,
+ struct riscv_iommu_msiptp_state *msiptp)
+{
+ struct riscv_iommu_bond *bond;
+ struct riscv_iommu_device *iommu, *prev;
+ struct riscv_iommu_command cmd;
+ struct iommu_fwspec *fwspec;
+ struct riscv_iommu_dc *dc;
+ int i;
+
+ /* Like riscv_iommu_ir_msitbl_inval(), synchronize with riscv_iommu_bond_link() */
+ smp_mb();
+ rcu_read_lock();
+
+ prev = NULL;
+ list_for_each_entry_rcu(bond, &domain->bonds, list) {
+ iommu = dev_to_iommu(bond->dev);
+ fwspec = dev_iommu_fwspec_get(bond->dev);
+
+ for (i = 0; i < fwspec->num_ids; i++) {
+ dc = riscv_iommu_get_dc(iommu, fwspec->ids[i]);
+ WRITE_ONCE(dc->msiptp, msiptp->msiptp);
+ WRITE_ONCE(dc->msi_addr_mask, msiptp->msi_addr_mask);
+ WRITE_ONCE(dc->msi_addr_pattern, msiptp->msi_addr_pattern);
+ }
+
+ dma_wmb();
+
+ if (iommu == prev)
+ continue;
+
+ riscv_iommu_cmd_inval_gvma(&cmd);
+ riscv_iommu_cmd_send(iommu, &cmd);
+ riscv_iommu_cmd_sync(iommu, RISCV_IOMMU_IOTINVAL_TIMEOUT);
+ prev = iommu;
+ }
+
+ rcu_read_unlock();
+}
+
+static int riscv_iommu_ir_msitbl_init(struct riscv_iommu_domain *domain,
+ struct riscv_iommu_vcpu_info *vcpu_info)
+{
+ domain->msiptp.msi_addr_pattern = vcpu_info->msi_addr_pattern;
+ domain->msiptp.msi_addr_mask = vcpu_info->msi_addr_mask;
+ domain->group_index_bits = vcpu_info->group_index_bits;
+ domain->group_index_shift = vcpu_info->group_index_shift;
+
+ if (riscv_iommu_ir_nr_msiptes(domain) * sizeof(*domain->msi_root) > PAGE_SIZE * 2)
+ return -ENOMEM;
+
+ domain->msiptp.msiptp = virt_to_pfn(domain->msi_root) |
+ FIELD_PREP(RISCV_IOMMU_DC_MSIPTP_MODE,
+ RISCV_IOMMU_DC_MSIPTP_MODE_FLAT);
+
+ riscv_iommu_ir_msitbl_update(domain, &domain->msiptp);
+
+ return 0;
+}
+
+static int riscv_iommu_irq_set_vcpu_affinity(struct irq_data *data, void *info)
+{
+ struct riscv_iommu_vcpu_info *vcpu_info = info;
+ struct riscv_iommu_domain *domain = data->domain->host_data;
+ struct riscv_iommu_msipte *pte;
+ int ret = -EINVAL;
+ u64 pteval;
+
+ if (WARN_ON(domain->domain.type != IOMMU_DOMAIN_UNMANAGED))
+ return ret;
+
+ spin_lock(&domain->msi_lock);
+
+ if (!domain->msiptp.msiptp) {
+ if (WARN_ON(!vcpu_info))
+ goto out_unlock;
+
+ ret = riscv_iommu_ir_msitbl_init(domain, vcpu_info);
+ if (ret)
+ goto out_unlock;
+ } else if (!vcpu_info) {
+ /*
+ * Nothing to do here since we don't track host_irq <=> msipte mappings
+ * nor reference count the ptes. If we did do that tracking then we would
+ * decrement the reference count of the pte for the host_irq and possibly
+ * clear its valid bit if it was the last one mapped.
+ */
+ ret = 0;
+ goto out_unlock;
+ } else if (WARN_ON(vcpu_info->msi_addr_pattern != domain->msiptp.msi_addr_pattern ||
+ vcpu_info->msi_addr_mask != domain->msiptp.msi_addr_mask ||
+ vcpu_info->group_index_bits != domain->group_index_bits ||
+ vcpu_info->group_index_shift != domain->group_index_shift)) {
+ goto out_unlock;
+ }
+
+ pte = riscv_iommu_ir_get_msipte(domain, vcpu_info->gpa);
+ if (!pte)
+ goto out_unlock;
+
+ pteval = FIELD_PREP(RISCV_IOMMU_MSIPTE_M, 3) |
+ riscv_iommu_phys_to_ppn(vcpu_info->hpa) |
+ FIELD_PREP(RISCV_IOMMU_MSIPTE_V, 1);
+
+ if (pte->pte != pteval) {
+ pte->pte = pteval;
+ riscv_iommu_ir_msitbl_inval(domain, pte);
+ }
+
+ ret = 0;
+
+out_unlock:
+ spin_unlock(&domain->msi_lock);
+ return ret;
+}
+
static struct irq_chip riscv_iommu_irq_chip = {
.name = "IOMMU-IR",
.irq_mask = irq_chip_mask_parent,
.irq_unmask = irq_chip_unmask_parent,
+ .irq_set_vcpu_affinity = riscv_iommu_irq_set_vcpu_affinity,
};

static int riscv_iommu_irq_domain_alloc_irqs(struct irq_domain *irqdomain,
diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
index c4a47b21c58f..46ac228ba7ac 100644
--- a/drivers/iommu/riscv/iommu.c
+++ b/drivers/iommu/riscv/iommu.c
@@ -544,8 +544,8 @@ static irqreturn_t riscv_iommu_fltq_process(int irq, void *data)
}

/* Lookup and initialize device context info structure. */
-static struct riscv_iommu_dc *riscv_iommu_get_dc(struct riscv_iommu_device *iommu,
- unsigned int devid)
+struct riscv_iommu_dc *riscv_iommu_get_dc(struct riscv_iommu_device *iommu,
+ unsigned int devid)
{
const bool base_format = !(iommu->caps & RISCV_IOMMU_CAPABILITIES_MSI_FLAT);
unsigned int depth;
diff --git a/drivers/iommu/riscv/iommu.h b/drivers/iommu/riscv/iommu.h
index 6ce71095781c..2ca76edf48f5 100644
--- a/drivers/iommu/riscv/iommu.h
+++ b/drivers/iommu/riscv/iommu.h
@@ -127,6 +127,9 @@ struct riscv_iommu_bond {
int riscv_iommu_init(struct riscv_iommu_device *iommu);
void riscv_iommu_remove(struct riscv_iommu_device *iommu);

+struct riscv_iommu_dc *riscv_iommu_get_dc(struct riscv_iommu_device *iommu,
+ unsigned int devid);
+
void riscv_iommu_cmd_send(struct riscv_iommu_device *iommu,
struct riscv_iommu_command *cmd);
void riscv_iommu_cmd_sync(struct riscv_iommu_device *iommu,
--
2.47.0