On Wed, Jan 06, 2021 at 08:33:50PM +0000, Wei Liu wrote:
> Just like MSI/MSI-X, IO-APIC interrupts are remapped by Microsoft
> Hypervisor when Linux runs as the root partition. Implement an IRQ chip
> to handle mapping and unmapping of IO-APIC interrupts.
>
> Use custom functions for mapping and unmapping ACPI GSIs. They will
> issue Microsoft Hypervisor specific hypercalls on top of the native
> routines.
>

This patch is superseded by a new patch I recently wrote.

The new approach is to implement a parent IRQ remapping domain for the
IO-APIC domain in Linux. It fits cleanly into Linux's architecture. No
more horrendous hooking required! :-)

Please review the following patch instead.

CC IOMMU maintainer. FYI.

---8<---
From 53d2346c97efdfc6ac3bc435990767bdd29ef311 Mon Sep 17 00:00:00 2001
From: Wei Liu <[email protected]>
Date: Fri, 8 Jan 2021 21:29:24 +0000
Subject: [PATCH] iommu/hyperv: setup an IO-APIC IRQ remapping domain for root
partition

Just like MSI/MSI-X, IO-APIC interrupts are remapped by Microsoft
Hypervisor when Linux runs as the root partition. Implement an IRQ
domain to handle mapping and unmapping of IO-APIC interrupts.

Signed-off-by: Wei Liu <[email protected]>
---
arch/x86/hyperv/irqdomain.c | 54 ++++++++++
arch/x86/include/asm/mshyperv.h | 4 +
drivers/iommu/hyperv-iommu.c | 179 +++++++++++++++++++++++++++++++-
3 files changed, 233 insertions(+), 4 deletions(-)

diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
index 19637cd60231..8e2b4e478b70 100644
--- a/arch/x86/hyperv/irqdomain.c
+++ b/arch/x86/hyperv/irqdomain.c
@@ -330,3 +330,57 @@ struct irq_domain * __init hv_create_pci_msi_domain(void)
}

#endif /* CONFIG_PCI_MSI */
+
+int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry)
+{
+ union hv_device_id device_id;
+
+ device_id.as_uint64 = 0;
+ device_id.device_type = HV_DEVICE_TYPE_IOAPIC;
+ device_id.ioapic.ioapic_id = (u8)ioapic_id;
+
+ return hv_unmap_interrupt(device_id.as_uint64, entry) & HV_HYPERCALL_RESULT_MASK;
+}
+EXPORT_SYMBOL_GPL(hv_unmap_ioapic_interrupt);
+
+int hv_map_ioapic_interrupt(int ioapic_id, bool level, int vcpu, int vector,
+ struct hv_interrupt_entry *entry)
+{
+ unsigned long flags;
+ struct hv_input_map_device_interrupt *input;
+ struct hv_output_map_device_interrupt *output;
+ union hv_device_id device_id;
+ struct hv_device_interrupt_descriptor *intr_desc;
+ u16 status;
+
+ device_id.as_uint64 = 0;
+ device_id.device_type = HV_DEVICE_TYPE_IOAPIC;
+ device_id.ioapic.ioapic_id = (u8)ioapic_id;
+
+ local_irq_save(flags);
+ input = *this_cpu_ptr(hyperv_pcpu_input_arg);
+ output = *this_cpu_ptr(hyperv_pcpu_output_arg);
+ memset(input, 0, sizeof(*input));
+ intr_desc = &input->interrupt_descriptor;
+ input->partition_id = hv_current_partition_id;
+ input->device_id = device_id.as_uint64;
+ intr_desc->interrupt_type = HV_X64_INTERRUPT_TYPE_FIXED;
+ intr_desc->target.vector = vector;
+ intr_desc->vector_count = 1;
+
+ if (level)
+ intr_desc->trigger_mode = HV_INTERRUPT_TRIGGER_MODE_LEVEL;
+ else
+ intr_desc->trigger_mode = HV_INTERRUPT_TRIGGER_MODE_EDGE;
+
+ __set_bit(vcpu, (unsigned long *)&intr_desc->target.vp_mask);
+
+ status = hv_do_rep_hypercall(HVCALL_MAP_DEVICE_INTERRUPT, 0, 0, input, output) &
+ HV_HYPERCALL_RESULT_MASK;
+ local_irq_restore(flags);
+
+ *entry = output->interrupt_entry;
+
+ return status;
+}
+EXPORT_SYMBOL_GPL(hv_map_ioapic_interrupt);
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index ccc849e25d5e..345d7c6f8c37 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -263,6 +263,10 @@ static inline void hv_set_msi_entry_from_desc(union hv_msi_entry *msi_entry,

struct irq_domain *hv_create_pci_msi_domain(void);

+int hv_map_ioapic_interrupt(int ioapic_id, bool level, int vcpu, int vector,
+ struct hv_interrupt_entry *entry);
+int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry);
+
#else /* CONFIG_HYPERV */
static inline void hyperv_init(void) {}
static inline void hyperv_setup_mmu_ops(void) {}
diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-iommu.c
index b7db6024e65c..6d35e4c303c6 100644
--- a/drivers/iommu/hyperv-iommu.c
+++ b/drivers/iommu/hyperv-iommu.c
@@ -116,30 +116,43 @@ static const struct irq_domain_ops hyperv_ir_domain_ops = {
.free = hyperv_irq_remapping_free,
};

+static const struct irq_domain_ops hyperv_root_ir_domain_ops;
static int __init hyperv_prepare_irq_remapping(void)
{
struct fwnode_handle *fn;
int i;
+ const char *name;
+ const struct irq_domain_ops *ops;

if (!hypervisor_is_type(X86_HYPER_MS_HYPERV) ||
x86_init.hyper.msi_ext_dest_id() ||
- !x2apic_supported() || hv_root_partition)
+ !x2apic_supported())
return -ENODEV;

- fn = irq_domain_alloc_named_id_fwnode("HYPERV-IR", 0);
+ if (hv_root_partition) {
+ name = "HYPERV-ROOT-IR";
+ ops = &hyperv_root_ir_domain_ops;
+ } else {
+ name = "HYPERV-IR";
+ ops = &hyperv_ir_domain_ops;
+ }
+
+ fn = irq_domain_alloc_named_id_fwnode(name, 0);
if (!fn)
return -ENOMEM;

ioapic_ir_domain =
irq_domain_create_hierarchy(arch_get_ir_parent_domain(),
- 0, IOAPIC_REMAPPING_ENTRY, fn,
- &hyperv_ir_domain_ops, NULL);
+ 0, IOAPIC_REMAPPING_ENTRY, fn, ops, NULL);

if (!ioapic_ir_domain) {
irq_domain_free_fwnode(fn);
return -ENOMEM;
}

+ if (hv_root_partition)
+ return 0; /* The rest is only relevant to guests */
+
/*
* Hyper-V doesn't provide irq remapping function for
* IO-APIC and so IO-APIC only accepts 8-bit APIC ID.
@@ -167,4 +180,162 @@ struct irq_remap_ops hyperv_irq_remap_ops = {
.enable = hyperv_enable_irq_remapping,
};

+/* IRQ remapping domain when Linux runs as the root partition */
+struct hyperv_root_ir_data {
+ u8 ioapic_id;
+ bool is_level;
+ struct hv_interrupt_entry entry;
+};
+
+static void
+hyperv_root_ir_compose_msi_msg(struct irq_data *irq_data, struct msi_msg *msg)
+{
+ u16 status;
+ u32 vector;
+ struct irq_cfg *cfg;
+ int ioapic_id;
+ struct cpumask *affinity;
+ int cpu, vcpu;
+ struct hv_interrupt_entry entry;
+ struct hyperv_root_ir_data *data = irq_data->chip_data;
+ struct IO_APIC_route_entry e;
+
+ cfg = irqd_cfg(irq_data);
+ affinity = irq_data_get_effective_affinity_mask(irq_data);
+ cpu = cpumask_first_and(affinity, cpu_online_mask);
+ vcpu = hv_cpu_number_to_vp_number(cpu);
+
+ vector = cfg->vector;
+ ioapic_id = data->ioapic_id;
+
+ if (data->entry.source == HV_DEVICE_TYPE_IOAPIC
+ && data->entry.ioapic_rte.as_uint64) {
+ entry = data->entry;
+
+ status = hv_unmap_ioapic_interrupt(ioapic_id, &entry);
+
+ if (status != HV_STATUS_SUCCESS)
+ pr_debug("%s: unexpected unmap status %d\n", __func__, status);
+
+ data->entry.ioapic_rte.as_uint64 = 0;
+ data->entry.source = 0; /* Invalid source */
+ }
+
+
+ status = hv_map_ioapic_interrupt(ioapic_id, data->is_level, vcpu,
+ vector, &entry);
+
+ if (status != HV_STATUS_SUCCESS) {
+ pr_err("%s: map hypercall failed, status %d\n", __func__, status);
+ return;
+ }
+
+ data->entry = entry;
+
+ /* Turn it into an IO_APIC_route_entry, and generate MSI MSG. */
+ e.w1 = entry.ioapic_rte.low_uint32;
+ e.w2 = entry.ioapic_rte.high_uint32;
+
+ memset(msg, 0, sizeof(*msg));
+ msg->arch_data.vector = e.vector;
+ msg->arch_data.delivery_mode = e.delivery_mode;
+ msg->arch_addr_lo.dest_mode_logical = e.dest_mode_logical;
+ msg->arch_addr_lo.dmar_format = e.ir_format;
+ msg->arch_addr_lo.dmar_index_0_14 = e.ir_index_0_14;
+}
+
+static int hyperv_root_ir_set_affinity(struct irq_data *data,
+ const struct cpumask *mask, bool force)
+{
+ struct irq_data *parent = data->parent_data;
+ struct irq_cfg *cfg = irqd_cfg(data);
+ int ret;
+
+ ret = parent->chip->irq_set_affinity(parent, mask, force);
+ if (ret < 0 || ret == IRQ_SET_MASK_OK_DONE)
+ return ret;
+
+ send_cleanup_vector(cfg);
+
+ return 0;
+}
+
+static struct irq_chip hyperv_root_ir_chip = {
+ .name = "HYPERV-ROOT-IR",
+ .irq_ack = apic_ack_irq,
+ .irq_set_affinity = hyperv_root_ir_set_affinity,
+ .irq_compose_msi_msg = hyperv_root_ir_compose_msi_msg,
+};
+
+static int hyperv_root_irq_remapping_alloc(struct irq_domain *domain,
+ unsigned int virq, unsigned int nr_irqs,
+ void *arg)
+{
+ struct irq_alloc_info *info = arg;
+ struct irq_data *irq_data;
+ struct hyperv_root_ir_data *data;
+ int ret = 0;
+
+ if (!info || info->type != X86_IRQ_ALLOC_TYPE_IOAPIC || nr_irqs > 1)
+ return -EINVAL;
+
+ ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, arg);
+ if (ret < 0)
+ return ret;
+
+ data = kzalloc(sizeof(*data), GFP_KERNEL);
+ if (!data) {
+ irq_domain_free_irqs_common(domain, virq, nr_irqs);
+ return -ENOMEM;
+ }
+
+ irq_data = irq_domain_get_irq_data(domain, virq);
+ if (!irq_data) {
+ kfree(data);
+ irq_domain_free_irqs_common(domain, virq, nr_irqs);
+ return -EINVAL;
+ }
+
+ data->ioapic_id = info->devid;
+ data->is_level = info->ioapic.is_level;
+
+ irq_data->chip = &hyperv_root_ir_chip;
+ irq_data->chip_data = data;
+
+ return 0;
+}
+
+static void hyperv_root_irq_remapping_free(struct irq_domain *domain,
+ unsigned int virq, unsigned int nr_irqs)
+{
+ struct irq_data *irq_data;
+ struct hyperv_root_ir_data *data;
+ struct hv_interrupt_entry *e;
+ int i;
+
+ for (i = 0; i < nr_irqs; i++) {
+ irq_data = irq_domain_get_irq_data(domain, virq + i);
+
+ if (irq_data && irq_data->chip_data) {
+ data = irq_data->chip_data;
+ e = &data->entry;
+
+ if (e->source == HV_DEVICE_TYPE_IOAPIC
+ && e->ioapic_rte.as_uint64)
+ hv_unmap_ioapic_interrupt(data->ioapic_id,
+ &data->entry);
+
+ kfree(data);
+ }
+ }
+
+ irq_domain_free_irqs_common(domain, virq, nr_irqs);
+}
+
+static const struct irq_domain_ops hyperv_root_ir_domain_ops = {
+ .select = hyperv_irq_remapping_select,
+ .alloc = hyperv_root_irq_remapping_alloc,
+ .free = hyperv_root_irq_remapping_free,
+};
+
#endif
--
2.20.1