1 /* 2 * X86 specific Hyper-V initialization code. 3 * 4 * Copyright (C) 2016, Microsoft, Inc. 5 * 6 * Author : K. Y. Srinivasan <kys@microsoft.com> 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License version 2 as published 10 * by the Free Software Foundation. 11 * 12 * This program is distributed in the hope that it will be useful, but 13 * WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or 15 * NON INFRINGEMENT. See the GNU General Public License for more 16 * details. 17 * 18 */ 19 20 #include <linux/types.h> 21 #include <asm/hypervisor.h> 22 #include <asm/hyperv.h> 23 #include <asm/mshyperv.h> 24 #include <linux/version.h> 25 #include <linux/vmalloc.h> 26 #include <linux/mm.h> 27 28 static void *hypercall_pg; 29 /* 30 * This function is to be invoked early in the boot sequence after the 31 * hypervisor has been detected. 32 * 33 * 1. Setup the hypercall page. 34 */ 35 void hyperv_init(void) 36 { 37 u64 guest_id; 38 union hv_x64_msr_hypercall_contents hypercall_msr; 39 40 if (x86_hyper != &x86_hyper_ms_hyperv) 41 return; 42 43 /* 44 * Setup the hypercall page and enable hypercalls. 45 * 1. Register the guest ID 46 * 2. Enable the hypercall and register the hypercall page 47 */ 48 guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0); 49 wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); 50 51 hypercall_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_EXEC); 52 if (hypercall_pg == NULL) { 53 wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); 54 return; 55 } 56 57 rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 58 hypercall_msr.enable = 1; 59 hypercall_msr.guest_physical_address = vmalloc_to_pfn(hypercall_pg); 60 wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); 61 } 62 63 /* 64 * hv_do_hypercall- Invoke the specified hypercall 65 */ 66 u64 hv_do_hypercall(u64 control, void *input, void *output) 67 { 68 u64 input_address = (input) ? virt_to_phys(input) : 0; 69 u64 output_address = (output) ? virt_to_phys(output) : 0; 70 #ifdef CONFIG_X86_64 71 u64 hv_status = 0; 72 73 if (!hypercall_pg) 74 return (u64)ULLONG_MAX; 75 76 __asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8"); 77 __asm__ __volatile__("call *%3" : "=a" (hv_status) : 78 "c" (control), "d" (input_address), 79 "m" (hypercall_pg)); 80 81 return hv_status; 82 83 #else 84 85 u32 control_hi = control >> 32; 86 u32 control_lo = control & 0xFFFFFFFF; 87 u32 hv_status_hi = 1; 88 u32 hv_status_lo = 1; 89 u32 input_address_hi = input_address >> 32; 90 u32 input_address_lo = input_address & 0xFFFFFFFF; 91 u32 output_address_hi = output_address >> 32; 92 u32 output_address_lo = output_address & 0xFFFFFFFF; 93 94 if (!hypercall_pg) 95 return (u64)ULLONG_MAX; 96 97 __asm__ __volatile__ ("call *%8" : "=d"(hv_status_hi), 98 "=a"(hv_status_lo) : "d" (control_hi), 99 "a" (control_lo), "b" (input_address_hi), 100 "c" (input_address_lo), "D"(output_address_hi), 101 "S"(output_address_lo), "m" (hypercall_pg)); 102 103 return hv_status_lo | ((u64)hv_status_hi << 32); 104 #endif /* !x86_64 */ 105 } 106 EXPORT_SYMBOL_GPL(hv_do_hypercall); 107