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Date:   Tue, 2 Feb 2021 17:02:48 +0000
From:   Wei Liu <wei.liu@kernel.org>
To:     Michael Kelley <mikelley@microsoft.com>
Cc:     Wei Liu <wei.liu@kernel.org>,
        Linux on Hyper-V List <linux-hyperv@vger.kernel.org>,
        "virtualization@lists.linux-foundation.org" 
        <virtualization@lists.linux-foundation.org>,
        Linux Kernel List <linux-kernel@vger.kernel.org>,
        Vineeth Pillai <viremana@linux.microsoft.com>,
        Sunil Muthuswamy <sunilmut@microsoft.com>,
        Nuno Das Neves <nunodasneves@linux.microsoft.com>,
        "pasha.tatashin@soleen.com" <pasha.tatashin@soleen.com>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Arnd Bergmann <arnd@arndb.de>,
        "open list:GENERIC INCLUDE/ASM HEADER FILES" 
        <linux-arch@vger.kernel.org>
Subject: Re: [PATCH v5 13/16] asm-generic/hyperv: introduce hv_device_id and
 auxiliary structures
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On Tue, Jan 26, 2021 at 01:26:52AM +0000, Michael Kelley wrote:
> From: Wei Liu <wei.liu@kernel.org> Sent: Wednesday, January 20, 2021 4:01 AM
> > 
> > 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 <sunilmut@microsoft.com>
> > Co-Developed-by: Sunil Muthuswamy <sunilmut@microsoft.com>
> > 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".

Wei.