Andy Lutomirski <luto@xxxxxxxxxx> writes:
> 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@xxxxxxxxxx>
>> Acked-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
>> Tested-by: Simon Xiao <sixiao@xxxxxxxxxxxxx>
>> Tested-by: Srikanth Myakam <v-srm@xxxxxxxxxxxxx>
>> ---
>> 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.
>
You mean I should do something like
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 359967f..f86c4ae 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -221,6 +221,7 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
{
union hv_hypercall_input control = {0};
+ register void *__sp asm(_ASM_SP);
control.code = code;
control.fast = 1;
@@ -228,8 +229,8 @@ static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
{
u64 hv_status;
- __asm__ __volatile__("call *%3"
- : "=a" (hv_status),
+ __asm__ __volatile__("call *%4"
+ : "=a" (hv_status), "+r" (__sp),
"+c" (control.as_uint64), "+d" (input1)
: "m" (hv_hypercall_pg)
: "cc", "r8", "r9", "r10", "r11");
@@ -241,10 +242,11 @@ static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
u32 input1_hi = (u32)(input1 >> 32);
u32 input1_lo = (u32)input1;
- __asm__ __volatile__ ("call *%6"
+ __asm__ __volatile__ ("call *%7"
: "=d"(hv_status_hi),
"=a"(hv_status_lo),
- "+c"(input1_lo)
+ "+c"(input1_lo),
+ "+r"(__sp)
: "d" (control.as_uint32_hi),
"a" (control.as_uint32_lo),
"b" (input1_hi),
(stollen from 0e8e2238)? hv_do_hypercall() will need this adjustment
too, I think.
--
Vitaly
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