xref: /openbmc/linux/arch/x86/kvm/kvm_onhyperv.c (revision 9ed3bf41)
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 
13 struct kvm_hv_tlb_range {
14 	u64 start_gfn;
15 	u64 pages;
16 };
17 
kvm_fill_hv_flush_list_func(struct hv_guest_mapping_flush_list * flush,void * data)18 static 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, range->start_gfn,
24 			range->pages);
25 }
26 
hv_remote_flush_root_tdp(hpa_t root_tdp,struct kvm_hv_tlb_range * range)27 static 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(root_tdp,
32 				kvm_fill_hv_flush_list_func, (void *)range);
33 	else
34 		return hyperv_flush_guest_mapping(root_tdp);
35 }
36 
__hv_flush_remote_tlbs_range(struct kvm * kvm,struct kvm_hv_tlb_range * range)37 static 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(&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, 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(kvm_arch->hv_root_tdp, range);
89 	}
90 
91 	spin_unlock(&kvm_arch->hv_root_tdp_lock);
92 	return ret;
93 }
94 
hv_flush_remote_tlbs_range(struct kvm * kvm,gfn_t start_gfn,gfn_t nr_pages)95 int 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);
103 }
104 EXPORT_SYMBOL_GPL(hv_flush_remote_tlbs_range);
105 
hv_flush_remote_tlbs(struct kvm * kvm)106 int hv_flush_remote_tlbs(struct kvm *kvm)
107 {
108 	return __hv_flush_remote_tlbs_range(kvm, NULL);
109 }
110 EXPORT_SYMBOL_GPL(hv_flush_remote_tlbs);
111 
hv_track_root_tdp(struct kvm_vcpu * vcpu,hpa_t root_tdp)112 void 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(&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(&kvm_arch->hv_root_tdp_lock);
122 	}
123 }
124 EXPORT_SYMBOL_GPL(hv_track_root_tdp);
125