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Subject[PATCH v8 04/10] x86/hyper-v: fast hypercall implementation
Date
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.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
arch/x86/include/asm/mshyperv.h | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)

diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index a004b3b..f3bedb4 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -211,6 +211,40 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
return hv_status;
}

+#define HV_HYPERCALL_FAST_BIT BIT(16)
+
+/* Fast hypercall with 8 bytes of input and no output */
+static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
+{
+ u64 hv_status, control = (u64)code | HV_HYPERCALL_FAST_BIT;
+ register void *__sp asm(_ASM_SP);
+
+#ifdef CONFIG_X86_64
+ {
+ __asm__ __volatile__("call *%4"
+ : "=a" (hv_status), "+r" (__sp),
+ "+c" (control), "+d" (input1)
+ : "m" (hv_hypercall_pg)
+ : "cc", "r8", "r9", "r10", "r11");
+ }
+#else
+ {
+ u32 input1_hi = upper_32_bits(input1);
+ u32 input1_lo = lower_32_bits(input1);
+
+ __asm__ __volatile__ ("call *%5"
+ : "=A"(hv_status),
+ "+c"(input1_lo),
+ "+r"(__sp)
+ : "A" (control),
+ "b" (input1_hi),
+ "m" (hv_hypercall_pg)
+ : "cc", "edi", "esi");
+ }
+#endif
+ return hv_status;
+}
+
void hyperv_init(void);
void hyperv_report_panic(struct pt_regs *regs);
bool hv_is_hypercall_page_setup(void);
--
2.9.4
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