[PATCH v0 11/15] x86/hyperv: Build logical device ids for PCI passthru hcalls

[Mukesh R <mrathor@linux.microsoft.com>]

From: Mukesh Rathor <mrathor@linux.microsoft.com>

On Hyper-V, most hypercalls related to PCI passthru to map/unmap regions,
interrupts, etc need a device id as a parameter. A device id refers
to a specific device. A device id is of two types:
   o Logical: used for direct attach (see below) hypercalls. A logical
              device id is a unique 62bit value that is created and
              sent during the initial device attach. Then all further
              communications (for interrupt remaps etc) must use this
              logical id.
   o PCI: used for device domain hypercalls such as map, unmap, etc.
          This is built using actual device BDF info.

   PS: Since an L1VH only supports direct attaches, a logical device id
       on an L1VH VM is always a VMBus device id. For non-L1VH cases,
       we just use PCI BDF info, altho not strictly needed, to build the
       logical device id.

At a high level, Hyper-V supports two ways to do PCI passthru:
  1. Device Domain: root must create a device domain in the hypervisor,
     and do map/unmap hypercalls for mapping and unmapping guest RAM.
     All hypervisor communications use device id of type PCI for
     identifying and referencing the device.

  2. Direct Attach: the hypervisor will simply use the guest's HW
     page table for mappings, thus the host need not do map/unmap
     hypercalls. A direct attached device must be referenced
     via logical device id and never via the PCI device id. For an
     L1VH root/parent, Hyper-V only supports direct attaches.

Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
 arch/x86/hyperv/irqdomain.c     | 60 ++++++++++++++++++++++++++++++---
 arch/x86/include/asm/mshyperv.h | 14 ++++++++
 2 files changed, 70 insertions(+), 4 deletions(-)

diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
index ccbe5848a28f..33017aa0caa4 100644
--- a/arch/x86/hyperv/irqdomain.c
+++ b/arch/x86/hyperv/irqdomain.c
@@ -137,7 +137,7 @@ static int get_rid_cb(struct pci_dev *pdev, u16 alias, void *data)
 	return 0;
 }
 
-static union hv_device_id hv_build_devid_type_pci(struct pci_dev *pdev)
+static u64 hv_build_devid_type_pci(struct pci_dev *pdev)
 {
 	int pos;
 	union hv_device_id hv_devid;
@@ -197,7 +197,58 @@ static union hv_device_id hv_build_devid_type_pci(struct pci_dev *pdev)
 	}
 
 out:
-	return hv_devid;
+	return hv_devid.as_uint64;
+}
+
+/* Build device id for direct attached devices */
+static u64 hv_build_devid_type_logical(struct pci_dev *pdev)
+{
+	hv_pci_segment segment;
+	union hv_device_id hv_devid;
+	union hv_pci_bdf bdf = {.as_uint16 = 0};
+	struct rid_data data = {
+		.bridge = NULL,
+		.rid = PCI_DEVID(pdev->bus->number, pdev->devfn)
+	};
+
+	segment = pci_domain_nr(pdev->bus);
+	bdf.bus = PCI_BUS_NUM(data.rid);
+	bdf.device = PCI_SLOT(data.rid);
+	bdf.function = PCI_FUNC(data.rid);
+
+	hv_devid.as_uint64 = 0;
+	hv_devid.device_type = HV_DEVICE_TYPE_LOGICAL;
+	hv_devid.logical.id = (u64)segment << 16 | bdf.as_uint16;
+
+	return hv_devid.as_uint64;
+}
+
+/* Build device id after the device has been attached */
+u64 hv_build_devid_oftype(struct pci_dev *pdev, enum hv_device_type type)
+{
+	if (type == HV_DEVICE_TYPE_LOGICAL) {
+		if (hv_l1vh_partition())
+			return hv_pci_vmbus_device_id(pdev);
+		else
+			return hv_build_devid_type_logical(pdev);
+	} else if (type == HV_DEVICE_TYPE_PCI)
+		return hv_build_devid_type_pci(pdev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hv_build_devid_oftype);
+
+/* Build device id for the interrupt path */
+static u64 hv_build_irq_devid(struct pci_dev *pdev)
+{
+	enum hv_device_type dev_type;
+
+	if (hv_pcidev_is_attached_dev(pdev) || hv_l1vh_partition())
+		dev_type = HV_DEVICE_TYPE_LOGICAL;
+	else
+		dev_type = HV_DEVICE_TYPE_PCI;
+
+	return hv_build_devid_oftype(pdev, dev_type);
 }
 
 /*
@@ -221,7 +272,7 @@ int hv_map_msi_interrupt(struct irq_data *data,
 
 	msidesc = irq_data_get_msi_desc(data);
 	pdev = msi_desc_to_pci_dev(msidesc);
-	hv_devid = hv_build_devid_type_pci(pdev);
+	hv_devid.as_uint64 = hv_build_irq_devid(pdev);
 	cpu = cpumask_first(irq_data_get_effective_affinity_mask(data));
 
 	return hv_map_interrupt(hv_current_partition_id, hv_devid, false, cpu,
@@ -296,7 +347,8 @@ static int hv_unmap_msi_interrupt(struct pci_dev *pdev,
 {
 	union hv_device_id hv_devid;
 
-	hv_devid = hv_build_devid_type_pci(pdev);
+	hv_devid.as_uint64 = hv_build_irq_devid(pdev);
+
 	return hv_unmap_interrupt(hv_devid.as_uint64, irq_entry);
 }
 
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 0d7fdfb25e76..97477c5a8487 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -188,6 +188,20 @@ bool hv_vcpu_is_preempted(int vcpu);
 static inline void hv_apic_init(void) {}
 #endif
 
+#if IS_ENABLED(CONFIG_HYPERV_IOMMU)
+static inline bool hv_pcidev_is_attached_dev(struct pci_dev *pdev)
+{ return false; }       /* temporary */
+u64 hv_build_devid_oftype(struct pci_dev *pdev, enum hv_device_type type);
+#else	/* CONFIG_HYPERV_IOMMU */
+static inline bool hv_pcidev_is_attached_dev(struct pci_dev *pdev)
+{ return false; }
+
+static inline u64 hv_build_devid_oftype(struct pci_dev *pdev,
+				       enum hv_device_type type)
+{ return 0; }
+
+#endif	/* CONFIG_HYPERV_IOMMU */
+
 u64 hv_pci_vmbus_device_id(struct pci_dev *pdev);
 
 struct irq_domain *hv_create_pci_msi_domain(void);
-- 
2.51.2.vfs.0.1