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From:   Michael Kelley <mikelley@microsoft.com>
To:     Wei Liu <wei.liu@kernel.org>,
        Joseph Salisbury <Joseph.Salisbury@microsoft.com>
CC:     KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
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        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
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Subject: RE: [PATCH 1/2] x86/hyperv: Move hv_do_rep_hypercall to asm-generic
Thread-Topic: [PATCH 1/2] x86/hyperv: Move hv_do_rep_hypercall to asm-generic
Thread-Index: AQHXMyKl7uqAeaa9w0ufXHoMj3A0Kqq6QbyAgAAVtlA=
Date:   Sun, 18 Apr 2021 14:42:55 +0000
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References: <1618620183-9967-1-git-send-email-joseph.salisbury@linux.microsoft.com>
 <20210418130903.5r66yzm6qxizfrop@liuwe-devbox-debian-v2>
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From: Wei Liu <wei.liu@kernel.org> Sent: Sunday, April 18, 2021 6:09 AM
> On Fri, Apr 16, 2021 at 05:43:02PM -0700, Joseph Salisbury wrote:
> > From: Joseph Salisbury <joseph.salisbury@microsoft.com>
> >
> > This patch makes no functional changes.  It simply moves hv_do_rep_hype=
rcall()
> > out of arch/x86/include/asm/mshyperv.h and into asm-generic/mshyperv.h
> >
> > hv_do_rep_hypercall() is architecture independent, so it makes sense th=
at it
> > should be in the architecture independent mshyperv.h, not in the x86-sp=
ecific
> > mshyperv.h.
> >
> > This is done in preperation for a follow up patch which creates a consi=
stent
> > pattern for checking Hyper-V hypercall status.
> >
> > Signed-off-by: Joseph Salisbury <joseph.salisbury@microsoft.com>
> > ---
> [...]
> > +static inline u64 hv_do_rep_hypercall(u16 code, u16 rep_count, u16 var=
head_size,
> > +				      void *input, void *output)
> > +{
> > +	u64 control =3D code;
> > +	u64 status;
> > +	u16 rep_comp;
> > +
> > +	control |=3D (u64)varhead_size << HV_HYPERCALL_VARHEAD_OFFSET;
> > +	control |=3D (u64)rep_count << HV_HYPERCALL_REP_COMP_OFFSET;
> > +
> > +	do {
> > +		status =3D hv_do_hypercall(control, input, output);
> > +		if ((status & HV_HYPERCALL_RESULT_MASK) !=3D HV_STATUS_SUCCESS)
> > +			return status;
> > +
> > +		/* Bits 32-43 of status have 'Reps completed' data. */
> > +		rep_comp =3D (status & HV_HYPERCALL_REP_COMP_MASK) >>
> > +			HV_HYPERCALL_REP_COMP_OFFSET;
> > +
> > +		control &=3D ~HV_HYPERCALL_REP_START_MASK;
> > +		control |=3D (u64)rep_comp << HV_HYPERCALL_REP_START_OFFSET;
> > +
> > +		touch_nmi_watchdog();
>=20
> This seems to be missing in Arm. Does it compile?
>=20
> Wei.

touch_nmi_watchdog() is defined as "static inline" in include/linux/nmi.h. =
 So
it should be present in all architectures.  It calls arch_touch_nmi_watchdo=
g,
which is an empty function if CONFIG_HAVE_NMI_WATCHDOG is not defined,
as is the case on ARM64.

Michael

>=20
> > +	} while (rep_comp < rep_count);
> > +
> > +	return status;
> > +}
> >
> >  /* Generate the guest OS identifier as described in the Hyper-V TLFS *=
/
> >  static inline  __u64 generate_guest_id(__u64 d_info1, __u64 kernel_ver=
sion,
> > --
> > 2.17.1
> >