From: Sunil Muthuswamy <sunilmut@xxxxxxxxxxxxxxxxxxx> Sent: Friday, December 17, 2021 10:52 AM
>
> Add arm64 Hyper-V vPCI support 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@xxxxxxxxxxxxx>
> ---
> In v2, v3, v4, v5, v6 & v7:
> 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 | 241 ++++++++++++++++++++++++++-
> 4 files changed, 251 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 43e615aa12ff..d98fafdd0f99 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 93b141110537..2536abcc045a 100644
> --- a/drivers/pci/controller/Kconfig
> +++ b/drivers/pci/controller/Kconfig
> @@ -281,7 +281,7 @@ 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 ead7d6cb6bf1..02ba2e7e2618 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 +616,236 @@ 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;
> +}
> +
> +/*
> + * @nr_bm_irqs: Indicates the number of IRQs that were allocated from
> + * the bitmap.
> + * @nr_dom_irqs: Indicates the number of IRQs that were allocated from
> + * the parent domain.
> + */
> +static void hv_pci_vec_irq_free(struct irq_domain *domain,
> + unsigned int virq,
> + unsigned int nr_bm_irqs,
> + unsigned int nr_dom_irqs)
> +{
> + struct hv_pci_chip_data *chip_data = domain->host_data;
> + struct irq_data *d = irq_domain_get_irq_data(domain, virq);
FWIW, irq_domain_get_irq_data() can return NULL. Maybe that's an
error in the "should never happen" category. Throughout kernel code,
some callers check for a NULL result, but a lot do not.
> + int first = d->hwirq - HV_PCI_MSI_SPI_START;
> + int i;
> +
> + mutex_lock(&chip_data->map_lock);
> + bitmap_release_region(chip_data->spi_map,
> + first,
> + get_count_order(nr_bm_irqs));
> + mutex_unlock(&chip_data->map_lock);
> + for (i = 0; i < nr_dom_irqs; i++) {
> + if (i)
> + d = irq_domain_get_irq_data(domain, virq + i);
Same here.
> + irq_domain_reset_irq_data(d);
> + }
> +
> + irq_domain_free_irqs_parent(domain, virq, nr_dom_irqs);
> +}
> +
> +static void hv_pci_vec_irq_domain_free(struct irq_domain *domain,
> + unsigned int virq,
> + unsigned int nr_irqs)
> +{
> + hv_pci_vec_irq_free(domain, virq, nr_irqs, 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;
> + struct irq_data *d;
> + int ret;
> +
> + fwspec.fwnode = domain->parent->fwnode;
> + fwspec.param_count = 2;
> + fwspec.param[0] = hwirq;
> + fwspec.param[1] = IRQ_TYPE_EDGE_RISING;
> +
> + ret = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
> + if (ret)
> + return ret;
> +
> + /*
> + * Since the interrupt specifier is not coming from ACPI or DT, the
> + * trigger type will need to be set explicitly. Otherwise, it will be
> + * set to whatever is in the GIC configuration.
> + */
> + d = irq_domain_get_irq_data(domain->parent, virq);
And here.
> +
> + return d->chip->irq_set_type(d, IRQ_TYPE_EDGE_RISING);
> +}
> +
> +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;
This error path doesn't clean up correctly. While parent IRQs allocated
in previous iterations of the loop is cleaned up, the parent IRQ
allocated in the current iteration is not.
> +
> + pr_debug("pID:%d vID:%u\n", (int)(hwirq + i), virq + i);
> + }
> +
> + return 0;
> +
> +free_irq:
> + hv_pci_vec_irq_free(domain, virq, nr_irqs, i);
> +
> + return ret;
> +}
> +
> +/*
> + * Pick the first online cpu 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.
> + */
> +static int hv_pci_vec_irq_domain_activate(struct irq_domain *domain,
> + struct irq_data *irqd, bool reserve)
> +{
> + int cpu = cpumask_first(cpu_online_mask);
Using the cpu_online_mask may work correctly, though its usage here
raises a red flag for me. The problem is that the CPU selected can go offline
immediately after the above line of code, as the cpus_read_lock() does
not appear to be held anywhere in the call stack. If the CPU is only
a temporary placeholder and will never actually be targeted with the
interrupt, then maybe the online/offline state doesn't matter. But if
that's the case, I'd suggest using the cpu_present_mask instead of the
cpu_online_mask. Hyper-V doesn't hot-add CPUs, so cpu_present_mask
should be stable even if the cpus_read_lock() isn't held, and the code
doesn't incorrectly imply that it's important for the CPU to be online.
Michael
> +
> + 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("hv_vpci_arm64");
> + 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 arm64 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 +1458,8 @@ 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 +1576,8 @@ 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);
> }
>
> @@ -1618,7 +1853,11 @@ static struct irq_chip hv_msi_irq_chip = {
> .name = "Hyper-V PCIe MSI",
> .irq_compose_msi_msg = hv_compose_msi_msg,
> .irq_set_affinity = irq_chip_set_affinity_parent,
> +#ifdef CONFIG_X86
> .irq_ack = irq_chip_ack_parent,
> +#elif defined(CONFIG_ARM64)
> + .irq_eoi = irq_chip_eoi_parent,
> +#endif
> .irq_mask = hv_irq_mask,
> .irq_unmask = hv_irq_unmask,
> };
> --
> 2.25.1
>
