> -----Original Message----- > From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx] > Sent: Friday, April 7, 2017 4:27 AM > To: devel@xxxxxxxxxxxxxxxxxxxxxx; x86@xxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx; KY Srinivasan <kys@xxxxxxxxxxxxx>; > Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; Stephen Hemminger > <sthemmin@xxxxxxxxxxxxx>; Thomas Gleixner <tglx@xxxxxxxxxxxxx>; Ingo > Molnar <mingo@xxxxxxxxxx>; H. Peter Anvin <hpa@xxxxxxxxx>; Steven > Rostedt <rostedt@xxxxxxxxxxx>; Jork Loeser <Jork.Loeser@xxxxxxxxxxxxx> > Subject: [PATCH 2/7] x86/hyper-v: fast hypercall implementation > > 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@xxxxxxxxxx> > --- > arch/x86/include/asm/mshyperv.h | 37 > +++++++++++++++++++++++++++++++++++++ > arch/x86/include/uapi/asm/hyperv.h | 19 +++++++++++++++++++ > 2 files changed, 56 insertions(+) > > diff --git a/arch/x86/include/asm/mshyperv.h > b/arch/x86/include/asm/mshyperv.h > index 331e834..9a5f58b 100644 > --- a/arch/x86/include/asm/mshyperv.h > +++ b/arch/x86/include/asm/mshyperv.h > @@ -216,6 +216,43 @@ 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}; Defining the hyper-call arguments on the stack can be problematic if CONFIG_VMAP_STACK is defined - since we are passing the guest physical address to the hypervisor, we cannot have the arguments straddle a page boundary. We have dealt with this issue currently by making sure the arguments are never on the stack via different means. Perhaps, we can allocate memory on a per-cpu basis that can be used for this purpose. In fact, this is what I have done for the hv_post_message hypercall. We can just rename that page and use it in all hypercalls - we can just allocate two pages on a per-CPU basis for this purpose (for input and output parameters). > + > + 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; > + > + __asm__ __volatile__ ("call *%6" > + : "=d"(hv_status_hi), > + "=a"(hv_status_lo) : > + "d" (control.as_uint32_hi), > + "a" (control.as_uint32_lo), > + "c" ((u32)input1), > + "b" ((u32)(input1 >> 32)), > + "m" (hv_hypercall_pg) > + : "cc"); > + > + return hv_status_lo | ((u64)hv_status_hi << 32); > + } > +#endif > +} > + > void hyperv_init(void); > void hyperv_report_panic(struct pt_regs *regs); > bool hv_is_hypercall_page_setup(void); > diff --git a/arch/x86/include/uapi/asm/hyperv.h > b/arch/x86/include/uapi/asm/hyperv.h > index 432df4b..c87e900 100644 > --- a/arch/x86/include/uapi/asm/hyperv.h > +++ b/arch/x86/include/uapi/asm/hyperv.h > @@ -256,6 +256,25 @@ > #define HV_PROCESSOR_POWER_STATE_C2 2 > #define HV_PROCESSOR_POWER_STATE_C3 3 > > +/* Hypercall interface */ > +union hv_hypercall_input { > + u64 as_uint64; > + struct { > + __u32 as_uint32_lo; > + __u32 as_uint32_hi; > + }; > + struct { > + __u64 code:16; > + __u64 fast:1; > + __u64 varhead_size:10; > + __u64 reserved1:5; > + __u64 rep_count:12; > + __u64 reserved2:4; > + __u64 rep_start:12; > + __u64 reserved3:4; > + }; > +}; > + > /* hypercall status code */ > #define HV_STATUS_SUCCESS 0 > #define HV_STATUS_INVALID_HYPERCALL_CODE 2 > -- > 2.9.3 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
