PCI: hv: Introduce hv_msi_entry

Add a new structure (hv_msi_entry), which is also defined in the TLFS,
to describe the msi entry for HVCALL_RETARGET_INTERRUPT. The structure
is needed because its layout may be different from architecture to
architecture.

Also add a new generic interface hv_set_msi_entry_from_desc() to allow
different archs to set the msi entry from msi_desc.

No functional change, only preparation for the future support of virtual
PCI on non-x86 architectures.
Signed-off-by: Boqun Feng (Microsoft) <boqun.feng@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>

arch/x86/include/asm/hyperv-tlfs.h

@@ -913,11 +913,18 @@ struct hv_partition_assist_pg {
 	u32 tlb_lock_count;
 };
 
+union hv_msi_entry {
+	u64 as_uint64;
+	struct {
+		u32 address;
+		u32 data;
+	} __packed;
+};
+
 struct hv_interrupt_entry {
 	u32 source;			/* 1 for MSI(-X) */
 	u32 reserved1;
-	u32 address;
-	u32 data;
+	union hv_msi_entry msi_entry;
 } __packed;
 
 /*

arch/x86/include/asm/mshyperv.h

@@ -4,6 +4,7 @@
 
 #include <linux/types.h>
 #include <linux/nmi.h>
+#include <linux/msi.h>
 #include <asm/io.h>
 #include <asm/hyperv-tlfs.h>
 #include <asm/nospec-branch.h>
@@ -240,6 +241,13 @@ bool hv_vcpu_is_preempted(int vcpu);
 static inline void hv_apic_init(void) {}
 #endif
 
+static inline void hv_set_msi_entry_from_desc(union hv_msi_entry *msi_entry,
+					      struct msi_desc *msi_desc)
+{
+	msi_entry->address = msi_desc->msg.address_lo;
+	msi_entry->data = msi_desc->msg.data;
+}
+
 #else /* CONFIG_HYPERV */
 static inline void hyperv_init(void) {}
 static inline void hyperv_setup_mmu_ops(void) {}

drivers/pci/controller/pci-hyperv.c

@@ -1213,8 +1213,7 @@ static void hv_irq_unmask(struct irq_data *data)
 	memset(params, 0, sizeof(*params));
 	params->partition_id = HV_PARTITION_ID_SELF;
 	params->int_entry.source = 1; /* MSI(-X) */
-	params->int_entry.address = msi_desc->msg.address_lo;
-	params->int_entry.data = msi_desc->msg.data;
+	hv_set_msi_entry_from_desc(&params->int_entry.msi_entry, msi_desc);
 	params->device_id = (hbus->hdev->dev_instance.b[5] << 24) |
 			   (hbus->hdev->dev_instance.b[4] << 16) |
 			   (hbus->hdev->dev_instance.b[7] << 8) |