1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * KVM L1 hypervisor optimizations on Hyper-V.
4 */
5#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
6
7#include <linux/kvm_host.h>
8#include <asm/mshyperv.h>
9
10#include "hyperv.h"
11#include "kvm_onhyperv.h"
12
13struct kvm_hv_tlb_range {
14 u64 start_gfn;
15 u64 pages;
16};
17
18static int kvm_fill_hv_flush_list_func(struct hv_guest_mapping_flush_list *flush,
19 void *data)
20{
21 struct kvm_hv_tlb_range *range = data;
22
23 return hyperv_fill_flush_guest_mapping_list(flush, start_gfn: range->start_gfn,
24 end_gfn: range->pages);
25}
26
27static inline int hv_remote_flush_root_tdp(hpa_t root_tdp,
28 struct kvm_hv_tlb_range *range)
29{
30 if (range)
31 return hyperv_flush_guest_mapping_range(as: root_tdp,
32 fill_func: kvm_fill_hv_flush_list_func, data: (void *)range);
33 else
34 return hyperv_flush_guest_mapping(as: root_tdp);
35}
36
37static int __hv_flush_remote_tlbs_range(struct kvm *kvm,
38 struct kvm_hv_tlb_range *range)
39{
40 struct kvm_arch *kvm_arch = &kvm->arch;
41 struct kvm_vcpu *vcpu;
42 int ret = 0, nr_unique_valid_roots;
43 unsigned long i;
44 hpa_t root;
45
46 spin_lock(lock: &kvm_arch->hv_root_tdp_lock);
47
48 if (!VALID_PAGE(kvm_arch->hv_root_tdp)) {
49 nr_unique_valid_roots = 0;
50
51 /*
52 * Flush all valid roots, and see if all vCPUs have converged
53 * on a common root, in which case future flushes can skip the
54 * loop and flush the common root.
55 */
56 kvm_for_each_vcpu(i, vcpu, kvm) {
57 root = vcpu->arch.hv_root_tdp;
58 if (!VALID_PAGE(root) || root == kvm_arch->hv_root_tdp)
59 continue;
60
61 /*
62 * Set the tracked root to the first valid root. Keep
63 * this root for the entirety of the loop even if more
64 * roots are encountered as a low effort optimization
65 * to avoid flushing the same (first) root again.
66 */
67 if (++nr_unique_valid_roots == 1)
68 kvm_arch->hv_root_tdp = root;
69
70 if (!ret)
71 ret = hv_remote_flush_root_tdp(root_tdp: root, range);
72
73 /*
74 * Stop processing roots if a failure occurred and
75 * multiple valid roots have already been detected.
76 */
77 if (ret && nr_unique_valid_roots > 1)
78 break;
79 }
80
81 /*
82 * The optimized flush of a single root can't be used if there
83 * are multiple valid roots (obviously).
84 */
85 if (nr_unique_valid_roots > 1)
86 kvm_arch->hv_root_tdp = INVALID_PAGE;
87 } else {
88 ret = hv_remote_flush_root_tdp(root_tdp: kvm_arch->hv_root_tdp, range);
89 }
90
91 spin_unlock(lock: &kvm_arch->hv_root_tdp_lock);
92 return ret;
93}
94
95int hv_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn, gfn_t nr_pages)
96{
97 struct kvm_hv_tlb_range range = {
98 .start_gfn = start_gfn,
99 .pages = nr_pages,
100 };
101
102 return __hv_flush_remote_tlbs_range(kvm, range: &range);
103}
104EXPORT_SYMBOL_FOR_KVM_INTERNAL(hv_flush_remote_tlbs_range);
105
106int hv_flush_remote_tlbs(struct kvm *kvm)
107{
108 return __hv_flush_remote_tlbs_range(kvm, NULL);
109}
110EXPORT_SYMBOL_FOR_KVM_INTERNAL(hv_flush_remote_tlbs);
111
112void hv_track_root_tdp(struct kvm_vcpu *vcpu, hpa_t root_tdp)
113{
114 struct kvm_arch *kvm_arch = &vcpu->kvm->arch;
115
116 if (kvm_x86_ops.flush_remote_tlbs == hv_flush_remote_tlbs) {
117 spin_lock(lock: &kvm_arch->hv_root_tdp_lock);
118 vcpu->arch.hv_root_tdp = root_tdp;
119 if (root_tdp != kvm_arch->hv_root_tdp)
120 kvm_arch->hv_root_tdp = INVALID_PAGE;
121 spin_unlock(lock: &kvm_arch->hv_root_tdp_lock);
122 }
123}
124EXPORT_SYMBOL_FOR_KVM_INTERNAL(hv_track_root_tdp);
125

source code of linux/arch/x86/kvm/kvm_onhyperv.c