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Date:   Wed, 3 Feb 2021 13:26:01 +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
Message-ID: <20210203132601.ftpwgs57qtok47cg@liuwe-devbox-debian-v2>
References: <20210120120058.29138-1-wei.liu@kernel.org>
 <20210120120058.29138-14-wei.liu@kernel.org>
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 <20210202170248.4hds554cyxpuayqc@liuwe-devbox-debian-v2>
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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:
> > 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".
> 

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

Wei.