[PATCH v4 2/2] arm64: PCI: hv: Add support for Hyper-V vPCI

Sunil Muthuswamy
2021-11-09T22:15:56Z

From: Sunil Muthuswamy <sunilmut@microsoft.com>

Add support for Hyper-V vPCI for arm64 by implementing the arch specific
interfaces. Introduce an IRQ domain and chip specific to Hyper-v vPCI that
is based on SPIs. The IRQ domain parents itself to the arch GIC IRQ domain
for basic vector management.

Signed-off-by: Sunil Muthuswamy <sunilmut@microsoft.com>
---
In v2, v3 & v4:
Changes are described in the cover letter.

arch/arm64/include/asm/hyperv-tlfs.h | 9 ++
drivers/pci/Kconfig | 2 +-
drivers/pci/controller/Kconfig | 2 +-
drivers/pci/controller/pci-hyperv.c | 207 ++++++++++++++++++++++++++-
4 files changed, 217 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/hyperv-tlfs.h b/arch/arm64/include/asm/hyperv-tlfs.h
index 4d964a7f02ee..bc6c7ac934a1 100644
--- a/arch/arm64/include/asm/hyperv-tlfs.h
+++ b/arch/arm64/include/asm/hyperv-tlfs.h
@@ -64,6 +64,15 @@
#define HV_REGISTER_STIMER0_CONFIG 0x000B0000
#define HV_REGISTER_STIMER0_COUNT 0x000B0001

+union hv_msi_entry {
+ u64 as_uint64[2];
+ struct {
+ u64 address;
+ u32 data;
+ u32 reserved;
+ } __packed;
+};
+
#include <asm-generic/hyperv-tlfs.h>

#endif
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index 0c473d75e625..cc2471488b61 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -184,7 +184,7 @@ config PCI_LABEL

config PCI_HYPERV
tristate "Hyper-V PCI Frontend"
- depends on X86_64 && HYPERV && PCI_MSI && PCI_MSI_IRQ_DOMAIN && SYSFS
+ depends on ((X86 && X86_64) || ARM64) && HYPERV && PCI_MSI && PCI_MSI_IRQ_DOMAIN && SYSFS
select PCI_HYPERV_INTERFACE
help
The PCI device frontend driver allows the kernel to import arbitrary
diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
index 326f7d13024f..b24edba0b870 100644
--- a/drivers/pci/controller/Kconfig
+++ b/drivers/pci/controller/Kconfig
@@ -280,7 +280,7 @@ config PCIE_BRCMSTB

config PCI_HYPERV_INTERFACE
tristate "Hyper-V PCI Interface"
- depends on X86 && HYPERV && PCI_MSI && PCI_MSI_IRQ_DOMAIN && X86_64
+ depends on ((X86 && X86_64) || ARM64) && HYPERV && PCI_MSI && PCI_MSI_IRQ_DOMAIN
help
The Hyper-V PCI Interface is a helper driver allows other drivers to
have a common interface with the Hyper-V PCI frontend driver.
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 03e07a4f0e3f..8ab57582b3a5 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -47,6 +47,8 @@
#include <linux/msi.h>
#include <linux/hyperv.h>
#include <linux/refcount.h>
+#include <linux/irqdomain.h>
+#include <linux/acpi.h>
#include <asm/mshyperv.h>

/*
@@ -614,7 +616,205 @@ static int hv_msi_prepare(struct irq_domain *domain, struct device *dev,
{
return pci_msi_prepare(domain, dev, nvec, info);
}
-#endif // CONFIG_X86
+#elif defined(CONFIG_ARM64)
+/*
+ * SPI vectors to use for vPCI; arch SPIs range is [32, 1019], but leaving a bit
+ * of room at the start to allow for SPIs to be specified through ACPI and
+ * starting with a power of two to satisfy power of 2 multi-MSI requirement.
+ */
+#define HV_PCI_MSI_SPI_START 64
+#define HV_PCI_MSI_SPI_NR (1020 - HV_PCI_MSI_SPI_START)
+#define DELIVERY_MODE 0
+#define FLOW_HANDLER NULL
+#define FLOW_NAME NULL
+#define hv_msi_prepare NULL
+
+struct hv_pci_chip_data {
+ DECLARE_BITMAP(spi_map, HV_PCI_MSI_SPI_NR);
+ struct mutex map_lock;
+};
+
+/* Hyper-V vPCI MSI GIC IRQ domain */
+static struct irq_domain *hv_msi_gic_irq_domain;
+
+/* Hyper-V PCI MSI IRQ chip */
+static struct irq_chip hv_arm64_msi_irq_chip = {
+ .name = "MSI",
+ .irq_set_affinity = irq_chip_set_affinity_parent,
+ .irq_eoi = irq_chip_eoi_parent,
+ .irq_mask = irq_chip_mask_parent,
+ .irq_unmask = irq_chip_unmask_parent
+};
+
+static unsigned int hv_msi_get_int_vector(struct irq_data *irqd)
+{
+ return irqd->parent_data->hwirq;
+}
+
+static void hv_set_msi_entry_from_desc(union hv_msi_entry *msi_entry,
+ struct msi_desc *msi_desc)
+{
+ msi_entry->address = ((u64)msi_desc->msg.address_hi << 32) |
+ msi_desc->msg.address_lo;
+ msi_entry->data = msi_desc->msg.data;
+}
+
+static void hv_pci_vec_irq_domain_free(struct irq_domain *domain,
+ unsigned int virq, unsigned int nr_irqs)
+{
+ struct hv_pci_chip_data *chip_data = domain->host_data;
+ struct irq_data *irqd = irq_domain_get_irq_data(domain, virq);
+ int first = irqd->hwirq - HV_PCI_MSI_SPI_START;
+
+ mutex_lock(&chip_data->map_lock);
+ bitmap_release_region(chip_data->spi_map,
+ first,
+ get_count_order(nr_irqs));
+ mutex_unlock(&chip_data->map_lock);
+ irq_domain_reset_irq_data(irqd);
+ irq_domain_free_irqs_parent(domain, virq, nr_irqs);
+}
+
+static int hv_pci_vec_alloc_device_irq(struct irq_domain *domain,
+ unsigned int nr_irqs,
+ irq_hw_number_t *hwirq)
+{
+ struct hv_pci_chip_data *chip_data = domain->host_data;
+ unsigned int index;
+
+ /* Find and allocate region from the SPI bitmap */
+ mutex_lock(&chip_data->map_lock);
+ index = bitmap_find_free_region(chip_data->spi_map,
+ HV_PCI_MSI_SPI_NR,
+ get_count_order(nr_irqs));
+ mutex_unlock(&chip_data->map_lock);
+ if (index < 0)
+ return -ENOSPC;
+
+ *hwirq = index + HV_PCI_MSI_SPI_START;
+
+ return 0;
+}
+
+static int hv_pci_vec_irq_gic_domain_alloc(struct irq_domain *domain,
+ unsigned int virq,
+ irq_hw_number_t hwirq)
+{
+ struct irq_fwspec fwspec;
+
+ fwspec.fwnode = domain->parent->fwnode;
+ fwspec.param_count = 2;
+ fwspec.param[0] = hwirq;
+ fwspec.param[1] = IRQ_TYPE_EDGE_RISING;
+
+ return irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
+}
+
+static int hv_pci_vec_irq_domain_alloc(struct irq_domain *domain,
+ unsigned int virq, unsigned int nr_irqs,
+ void *args)
+{
+ irq_hw_number_t hwirq;
+ unsigned int i;
+ int ret;
+
+ ret = hv_pci_vec_alloc_device_irq(domain, nr_irqs, &hwirq);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < nr_irqs; i++) {
+ ret = hv_pci_vec_irq_gic_domain_alloc(domain, virq + i,
+ hwirq + i);
+ if (ret)
+ goto free_irq;
+
+ ret = irq_domain_set_hwirq_and_chip(domain, virq + i,
+ hwirq + i,
+ &hv_arm64_msi_irq_chip,
+ domain->host_data);
+ if (ret)
+ goto free_irq;
+
+ pr_debug("pID:%d vID:%u\n", (int)(hwirq + i), virq + i);
+ }
+
+ return 0;
+
+free_irq:
+ hv_pci_vec_irq_domain_free(domain, virq, nr_irqs);
+
+ return ret;
+}
+
+static int hv_pci_vec_irq_domain_activate(struct irq_domain *domain,
+ struct irq_data *irqd, bool reserve)
+{
+ static int cpu;
+
+ /*
+ * Pick a cpu using round-robin as the irq affinity that can be
+ * temporarily used for composing MSI from the hypervisor. GIC
+ * will eventually set the right affinity for the irq and the
+ * 'unmask' will retarget the interrupt to that cpu.
+ */
+ if (cpu >= cpumask_last(cpu_online_mask))
+ cpu = 0;
+ cpu = cpumask_next(cpu, cpu_online_mask);
+ irq_data_update_effective_affinity(irqd, cpumask_of(cpu));
+
+ return 0;
+}
+
+static const struct irq_domain_ops hv_pci_domain_ops = {
+ .alloc = hv_pci_vec_irq_domain_alloc,
+ .free = hv_pci_vec_irq_domain_free,
+ .activate = hv_pci_vec_irq_domain_activate,
+};
+
+static int hv_pci_irqchip_init(void)
+{
+ static struct hv_pci_chip_data *chip_data;
+ struct fwnode_handle *fn = NULL;
+ int ret = -ENOMEM;
+
+ chip_data = kzalloc(sizeof(*chip_data), GFP_KERNEL);
+ if (!chip_data)
+ return ret;
+
+ mutex_init(&chip_data->map_lock);
+ fn = irq_domain_alloc_named_fwnode("Hyper-V ARM64 vPCI");
+ if (!fn)
+ goto free_chip;
+
+ /*
+ * IRQ domain once enabled, should not be removed since there is no
+ * way to ensure that all the corresponding devices are also gone and
+ * no interrupts will be generated.
+ */
+ hv_msi_gic_irq_domain = acpi_irq_create_hierarchy(0, HV_PCI_MSI_SPI_NR,
+ fn, &hv_pci_domain_ops,
+ chip_data);
+
+ if (!hv_msi_gic_irq_domain) {
+ pr_err("Failed to create Hyper-V ARMV vPCI MSI IRQ domain\n");
+ goto free_chip;
+ }
+
+ return 0;
+
+free_chip:
+ kfree(chip_data);
+ if (fn)
+ irq_domain_free_fwnode(fn);
+
+ return ret;
+}
+
+static struct irq_domain *hv_pci_get_root_domain(void)
+{
+ return hv_msi_gic_irq_domain;
+}
+#endif //CONFIG_ARM64

/**
* hv_pci_generic_compl() - Invoked for a completion packet
@@ -1227,6 +1427,8 @@ static void hv_msi_free(struct irq_domain *domain, struct msi_domain_info *info,
static void hv_irq_mask(struct irq_data *data)
{
pci_msi_mask_irq(data);
+ if (data->parent_data->chip->irq_mask)
+ irq_chip_mask_parent(data);
}

/**
@@ -1343,6 +1545,8 @@ static void hv_irq_unmask(struct irq_data *data)
dev_err(&hbus->hdev->device,
"%s() failed: %#llx", __func__, res);

+ if (data->parent_data->chip->irq_unmask)
+ irq_chip_unmask_parent(data);
pci_msi_unmask_irq(data);
}

@@ -1619,6 +1823,7 @@ static struct irq_chip hv_msi_irq_chip = {
.irq_compose_msi_msg = hv_compose_msi_msg,
.irq_set_affinity = irq_chip_set_affinity_parent,
.irq_ack = irq_chip_ack_parent,
+ .irq_eoi = irq_chip_eoi_parent,
.irq_mask = hv_irq_mask,
.irq_unmask = hv_irq_unmask,
};
--
2.25.1