1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /******************************************************************************
3  * asm-x86/guest/hyperv.h
4  *
5  * Copyright (c) 2019 Microsoft.
6  */
7 
8 #ifndef __X86_GUEST_HYPERV_H__
9 #define __X86_GUEST_HYPERV_H__
10 
11 #include <xen/types.h>
12 
13 /* Use top-most MFN for hypercall page */
14 #define HV_HCALL_MFN   (((1ull << paddr_bits) - 1) >> HV_HYP_PAGE_SHIFT)
15 
16 /*
17  * The specification says: "The partition reference time is computed
18  * by the following formula:
19  *
20  * ReferenceTime = ((VirtualTsc * TscScale) >> 64) + TscOffset
21  *
22  * The multiplication is a 64 bit multiplication, which results in a
23  * 128 bit number which is then shifted 64 times to the right to obtain
24  * the high 64 bits."
25  */
hv_scale_tsc(uint64_t tsc,uint64_t scale,int64_t offset)26 static inline uint64_t hv_scale_tsc(uint64_t tsc, uint64_t scale,
27                                     int64_t offset)
28 {
29     uint64_t result;
30 
31     /*
32      * Quadword MUL takes an implicit operand in RAX, and puts the result
33      * in RDX:RAX. Because we only want the result of the multiplication
34      * after shifting right by 64 bits, we therefore only need the content
35      * of RDX.
36      */
37     asm ( "mulq %[scale]"
38           : "+a" (tsc), "=d" (result)
39           : [scale] "rm" (scale) );
40 
41     return result + offset;
42 }
43 
44 #ifdef CONFIG_HYPERV_GUEST
45 
46 #include <asm/guest/hypervisor.h>
47 
48 struct ms_hyperv_info {
49     uint32_t features;
50     uint32_t misc_features;
51     uint32_t hints;
52     uint32_t nested_features;
53     uint32_t max_vp_index;
54     uint32_t max_lp_index;
55 };
56 extern struct ms_hyperv_info ms_hyperv;
57 
58 const struct hypervisor_ops *hyperv_probe(void);
59 
60 #else
61 
hyperv_probe(void)62 static inline const struct hypervisor_ops *hyperv_probe(void) { return NULL; }
63 
64 #endif /* CONFIG_HYPERV_GUEST */
65 #endif /* __X86_GUEST_HYPERV_H__ */
66 
67 /*
68  * Local variables:
69  * mode: C
70  * c-file-style: "BSD"
71  * c-basic-offset: 4
72  * tab-width: 4
73  * indent-tabs-mode: nil
74  * End:
75  */
76