Re: [PATCH v5 13/16] asm-generic/hyperv: introduce hv_device_id and auxiliary structures

On Tue, Feb 02, 2021 at 05:02:48PM +0000, Wei Liu wrote:

On Tue, Jan 26, 2021 at 01:26:52AM +0000, Michael Kelley wrote:

quoted

From: Wei Liu <wei.liu@kernel.org> Sent: Wednesday, January 20, 2021 4:01 AM

quoted

We will need to identify the device we want Microsoft Hypervisor to
manipulate.  Introduce the data structures for that purpose.

They will be used in a later patch.

Signed-off-by: Sunil Muthuswamy <redacted>
Co-Developed-by: Sunil Muthuswamy <redacted>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
---
 include/asm-generic/hyperv-tlfs.h | 79 +++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index 8423bf53c237..42ff1326c6bd 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h

@@ -623,4 +623,83 @@ struct hv_set_vp_registers_input {
 	} element[];
 } __packed;

+enum hv_device_type {
+	HV_DEVICE_TYPE_LOGICAL = 0,
+	HV_DEVICE_TYPE_PCI = 1,
+	HV_DEVICE_TYPE_IOAPIC = 2,
+	HV_DEVICE_TYPE_ACPI = 3,
+};
+
+typedef u16 hv_pci_rid;
+typedef u16 hv_pci_segment;
+typedef u64 hv_logical_device_id;
+union hv_pci_bdf {
+	u16 as_uint16;
+
+	struct {
+		u8 function:3;
+		u8 device:5;
+		u8 bus;
+	};
+} __packed;
+
+union hv_pci_bus_range {
+	u16 as_uint16;
+
+	struct {
+		u8 subordinate_bus;
+		u8 secondary_bus;
+	};
+} __packed;
+
+union hv_device_id {
+	u64 as_uint64;
+
+	struct {
+		u64 :62;
+		u64 device_type:2;
+	};

Are the above 4 lines extraneous junk? 
If not, a comment would be helpful.  And we
would normally label the 62 bit field as 
"reserved0" or something similar.

No. It is not junk. I got this from a header in tree.

I am inclined to just drop this hunk. If that breaks things, I will use
"reserved0".

It turns out adding reserved0 is required. Dropping this hunk does not
work.

Wei.