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Message-ID: <BY2PR0301MB16540A401739AB491BF4C92BA0EE0@BY2PR0301MB1654.namprd03.prod.outlook.com>
Date: Tue, 15 Dec 2015 04:13:55 +0000
From: KY Srinivasan <kys@...rosoft.com>
To: Greg KH <gregkh@...uxfoundation.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
"olaf@...fle.de" <olaf@...fle.de>,
"apw@...onical.com" <apw@...onical.com>,
"vkuznets@...hat.com" <vkuznets@...hat.com>,
"jasowang@...hat.com" <jasowang@...hat.com>,
Jake Oshins <jakeo@...rosoft.com>
Subject: RE: [PATCH RESEND 09/27] drivers:hv: Export the API to invoke a
hypercall on Hyper-V
> -----Original Message-----
> From: Greg KH [mailto:gregkh@...uxfoundation.org]
> Sent: Monday, December 14, 2015 7:08 PM
> To: KY Srinivasan <kys@...rosoft.com>
> Cc: linux-kernel@...r.kernel.org; devel@...uxdriverproject.org;
> olaf@...fle.de; apw@...onical.com; vkuznets@...hat.com;
> jasowang@...hat.com; Jake Oshins <jakeo@...rosoft.com>
> Subject: Re: [PATCH RESEND 09/27] drivers:hv: Export the API to invoke a
> hypercall on Hyper-V
>
> On Mon, Dec 14, 2015 at 04:01:40PM -0800, K. Y. Srinivasan wrote:
> > From: Jake Oshins <jakeo@...rosoft.com>
> >
> > This patch exposes the function that hv_vmbus.ko uses to make hypercalls.
> This
> > is necessary for retargeting an interrupt when it is given a new affinity.
> >
> > Since we are exporting this API, rename the API as it will be visible outside
> > the hv.c file.
> >
> > Signed-off-by: Jake Oshins <jakeo@...rosoft.com>
> > Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> > ---
> > drivers/hv/hv.c | 20 ++++++++++----------
> > drivers/hv/hyperv_vmbus.h | 2 +-
> > include/linux/hyperv.h | 1 +
> > 3 files changed, 12 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> > index 6341be8..7a06933 100644
> > --- a/drivers/hv/hv.c
> > +++ b/drivers/hv/hv.c
> > @@ -89,9 +89,9 @@ static int query_hypervisor_info(void)
> > }
> >
> > /*
> > - * do_hypercall- Invoke the specified hypercall
> > + * hv_do_hypercall- Invoke the specified hypercall
> > */
> > -static u64 do_hypercall(u64 control, void *input, void *output)
> > +u64 hv_do_hypercall(u64 control, void *input, void *output)
> > {
> > u64 input_address = (input) ? virt_to_phys(input) : 0;
> > u64 output_address = (output) ? virt_to_phys(output) : 0;
> > @@ -132,6 +132,7 @@ static u64 do_hypercall(u64 control, void *input,
> void *output)
> > return hv_status_lo | ((u64)hv_status_hi << 32);
> > #endif /* !x86_64 */
> > }
> > +EXPORT_SYMBOL_GPL(hv_do_hypercall);
> >
> > #ifdef CONFIG_X86_64
> > static cycle_t read_hv_clock_tsc(struct clocksource *arg)
> > @@ -315,7 +316,7 @@ int hv_post_message(union hv_connection_id
> connection_id,
> > {
> >
> > struct hv_input_post_message *aligned_msg;
> > - u16 status;
> > + u64 status;
> >
> > if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
> > return -EMSGSIZE;
> > @@ -329,11 +330,10 @@ int hv_post_message(union hv_connection_id
> connection_id,
> > aligned_msg->payload_size = payload_size;
> > memcpy((void *)aligned_msg->payload, payload, payload_size);
> >
> > - status = do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL)
> > - & 0xFFFF;
> > + status = hv_do_hypercall(HVCALL_POST_MESSAGE, aligned_msg,
> NULL);
> >
> > put_cpu();
> > - return status;
> > + return status & 0xFFFF;
> > }
> >
> >
> > @@ -343,13 +343,13 @@ int hv_post_message(union hv_connection_id
> connection_id,
> > *
> > * This involves a hypercall.
> > */
> > -u16 hv_signal_event(void *con_id)
> > +int hv_signal_event(void *con_id)
> > {
> > - u16 status;
> > + u64 status;
> >
> > - status = (do_hypercall(HVCALL_SIGNAL_EVENT, con_id, NULL) &
> 0xFFFF);
> > + status = hv_do_hypercall(HVCALL_SIGNAL_EVENT, con_id, NULL);
> >
> > - return status;
> > + return status & 0xFFFF;
>
> This "feels" odd, as the return value isn't the traditional 0 or -ERROR,
> right? Why are you masking off the top bits?
>
> And, no one ever does anything with the return value of
> hv_signal_event(), so why have it return anything anyway?
>
> I'll take this, but please fix up the area, it's messy...
Thanks Greg. Will do.
K. Y
>
> greg k-h
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