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Date: Sat, 20 May 2017 20:18:15 -0700 From: Andy Lutomirski <luto@...nel.org> To: Vitaly Kuznetsov <vkuznets@...hat.com>, devel@...uxdriverproject.org Cc: Stephen Hemminger <sthemmin@...rosoft.com>, Jork Loeser <Jork.Loeser@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>, x86@...nel.org, linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>, Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>, Thomas Gleixner <tglx@...utronix.de> Subject: Re: [PATCH v3 04/10] x86/hyper-v: fast hypercall implementation On 05/19/2017 07:09 AM, Vitaly Kuznetsov wrote: > Hyper-V supports 'fast' hypercalls when all parameters are passed through > registers. Implement an inline version of a simpliest of these calls: > hypercall with one 8-byte input and no output. > > Proper hypercall input interface (struct hv_hypercall_input) definition is > added as well. > > Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com> > Acked-by: K. Y. Srinivasan <kys@...rosoft.com> > Tested-by: Simon Xiao <sixiao@...rosoft.com> > Tested-by: Srikanth Myakam <v-srm@...rosoft.com> > --- > arch/x86/include/asm/mshyperv.h | 39 ++++++++++++++++++++++++++++++++++++++ > arch/x86/include/uapi/asm/hyperv.h | 19 +++++++++++++++++++ > 2 files changed, 58 insertions(+) > > diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h > index e293937..028e29b 100644 > --- a/arch/x86/include/asm/mshyperv.h > +++ b/arch/x86/include/asm/mshyperv.h > @@ -216,6 +216,45 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output) > #endif /* !x86_64 */ > } > > +/* Fast hypercall with 8 bytes of input and no output */ > +static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1) > +{ > + union hv_hypercall_input control = {0}; > + > + control.code = code; > + control.fast = 1; > +#ifdef CONFIG_X86_64 > + { > + u64 hv_status; > + > + __asm__ __volatile__("call *%3" > + : "=a" (hv_status), > + "+c" (control.as_uint64), "+d" (input1) > + : "m" (hv_hypercall_pg) > + : "cc", "r8", "r9", "r10", "r11"); > + return hv_status; > + } > +#else > + { > + u32 hv_status_hi, hv_status_lo; > + u32 input1_hi = (u32)(input1 >> 32); > + u32 input1_lo = (u32)input1; > + > + __asm__ __volatile__ ("call *%6" > + : "=d"(hv_status_hi), > + "=a"(hv_status_lo), > + "+c"(input1_lo) > + : "d" (control.as_uint32_hi), > + "a" (control.as_uint32_lo), > + "b" (input1_hi), > + "m" (hv_hypercall_pg) > + : "cc", "edi", "esi"); > + > + return hv_status_lo | ((u64)hv_status_hi << 32); > + } > +#endif This is going to need an explicit "sp" annotation to force a stack frame, I think. Otherwise objtool is likely to get mad in a frame-pointer-omitted build.
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