xref: /freebsd/sys/amd64/vmm/amd/svm_msr.c (revision 9268022b74279434ed6300244e3f977e56a8ceb5)
1 /*-
2  * Copyright (c) 2014, Neel Natu (neel@freebsd.org)
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice unmodified, this list of conditions, and the following
10  *    disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <sys/types.h>
31 #include <sys/errno.h>
32 
33 #include <machine/cpufunc.h>
34 #include <machine/specialreg.h>
35 
36 #include "svm_msr.h"
37 
38 #ifndef MSR_AMDK8_IPM
39 #define	MSR_AMDK8_IPM	0xc0010055
40 #endif
41 
42 enum {
43 	IDX_MSR_LSTAR,
44 	IDX_MSR_CSTAR,
45 	IDX_MSR_STAR,
46 	IDX_MSR_SF_MASK,
47 	HOST_MSR_NUM		/* must be the last enumeration */
48 };
49 
50 static uint64_t host_msrs[HOST_MSR_NUM];
51 
52 void
53 svm_msr_init(void)
54 {
55 	/*
56 	 * It is safe to cache the values of the following MSRs because they
57 	 * don't change based on curcpu, curproc or curthread.
58 	 */
59 	host_msrs[IDX_MSR_LSTAR] = rdmsr(MSR_LSTAR);
60 	host_msrs[IDX_MSR_CSTAR] = rdmsr(MSR_CSTAR);
61 	host_msrs[IDX_MSR_STAR] = rdmsr(MSR_STAR);
62 	host_msrs[IDX_MSR_SF_MASK] = rdmsr(MSR_SF_MASK);
63 }
64 
65 void
66 svm_msr_guest_init(struct svm_softc *sc, int vcpu)
67 {
68 	/*
69 	 * All the MSRs accessible to the guest are either saved/restored by
70 	 * hardware on every #VMEXIT/VMRUN (e.g., G_PAT) or are saved/restored
71 	 * by VMSAVE/VMLOAD (e.g., MSR_GSBASE).
72 	 *
73 	 * There are no guest MSRs that are saved/restored "by hand" so nothing
74 	 * more to do here.
75 	 */
76 	return;
77 }
78 
79 void
80 svm_msr_guest_enter(struct svm_softc *sc, int vcpu)
81 {
82 	/*
83 	 * Save host MSRs (if any) and restore guest MSRs (if any).
84 	 */
85 }
86 
87 void
88 svm_msr_guest_exit(struct svm_softc *sc, int vcpu)
89 {
90 	/*
91 	 * Save guest MSRs (if any) and restore host MSRs.
92 	 */
93 	wrmsr(MSR_LSTAR, host_msrs[IDX_MSR_LSTAR]);
94 	wrmsr(MSR_CSTAR, host_msrs[IDX_MSR_CSTAR]);
95 	wrmsr(MSR_STAR, host_msrs[IDX_MSR_STAR]);
96 	wrmsr(MSR_SF_MASK, host_msrs[IDX_MSR_SF_MASK]);
97 
98 	/* MSR_KGSBASE will be restored on the way back to userspace */
99 }
100 
101 int
102 svm_rdmsr(struct svm_softc *sc, int vcpu, u_int num, uint64_t *result,
103     bool *retu)
104 {
105 	int error = 0;
106 
107 	switch (num) {
108 	case MSR_AMDK8_IPM:
109 		*result = 0;
110 		break;
111 	default:
112 		error = EINVAL;
113 		break;
114 	}
115 
116 	return (error);
117 }
118 
119 int
120 svm_wrmsr(struct svm_softc *sc, int vcpu, u_int num, uint64_t val, bool *retu)
121 {
122 	int error = 0;
123 
124 	switch (num) {
125 	case MSR_AMDK8_IPM:
126 		/*
127 		 * Ignore writes to the "Interrupt Pending Message" MSR.
128 		 */
129 		break;
130 	default:
131 		error = EINVAL;
132 		break;
133 	}
134 
135 	return (error);
136 }
137