xref: /openbmc/linux/arch/arm64/kvm/hyp/vhe/sysreg-sr.c (revision 1ff2755d)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2012-2015 - ARM Ltd
4  * Author: Marc Zyngier <marc.zyngier@arm.com>
5  */
6 
7 #include <hyp/sysreg-sr.h>
8 
9 #include <linux/compiler.h>
10 #include <linux/kvm_host.h>
11 
12 #include <asm/kprobes.h>
13 #include <asm/kvm_asm.h>
14 #include <asm/kvm_emulate.h>
15 #include <asm/kvm_hyp.h>
16 #include <asm/kvm_nested.h>
17 
18 /*
19  * VHE: Host and guest must save mdscr_el1 and sp_el0 (and the PC and
20  * pstate, which are handled as part of the el2 return state) on every
21  * switch (sp_el0 is being dealt with in the assembly code).
22  * tpidr_el0 and tpidrro_el0 only need to be switched when going
23  * to host userspace or a different VCPU.  EL1 registers only need to be
24  * switched when potentially going to run a different VCPU.  The latter two
25  * classes are handled as part of kvm_arch_vcpu_load and kvm_arch_vcpu_put.
26  */
27 
sysreg_save_host_state_vhe(struct kvm_cpu_context * ctxt)28 void sysreg_save_host_state_vhe(struct kvm_cpu_context *ctxt)
29 {
30 	__sysreg_save_common_state(ctxt);
31 }
32 NOKPROBE_SYMBOL(sysreg_save_host_state_vhe);
33 
sysreg_save_guest_state_vhe(struct kvm_cpu_context * ctxt)34 void sysreg_save_guest_state_vhe(struct kvm_cpu_context *ctxt)
35 {
36 	__sysreg_save_common_state(ctxt);
37 	__sysreg_save_el2_return_state(ctxt);
38 }
39 NOKPROBE_SYMBOL(sysreg_save_guest_state_vhe);
40 
sysreg_restore_host_state_vhe(struct kvm_cpu_context * ctxt)41 void sysreg_restore_host_state_vhe(struct kvm_cpu_context *ctxt)
42 {
43 	__sysreg_restore_common_state(ctxt);
44 }
45 NOKPROBE_SYMBOL(sysreg_restore_host_state_vhe);
46 
sysreg_restore_guest_state_vhe(struct kvm_cpu_context * ctxt)47 void sysreg_restore_guest_state_vhe(struct kvm_cpu_context *ctxt)
48 {
49 	__sysreg_restore_common_state(ctxt);
50 	__sysreg_restore_el2_return_state(ctxt);
51 }
52 NOKPROBE_SYMBOL(sysreg_restore_guest_state_vhe);
53 
54 /**
55  * kvm_vcpu_load_sysregs_vhe - Load guest system registers to the physical CPU
56  *
57  * @vcpu: The VCPU pointer
58  *
59  * Load system registers that do not affect the host's execution, for
60  * example EL1 system registers on a VHE system where the host kernel
61  * runs at EL2.  This function is called from KVM's vcpu_load() function
62  * and loading system register state early avoids having to load them on
63  * every entry to the VM.
64  */
kvm_vcpu_load_sysregs_vhe(struct kvm_vcpu * vcpu)65 void kvm_vcpu_load_sysregs_vhe(struct kvm_vcpu *vcpu)
66 {
67 	struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
68 	struct kvm_cpu_context *host_ctxt;
69 
70 	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
71 	__sysreg_save_user_state(host_ctxt);
72 
73 	/*
74 	 * When running a normal EL1 guest, we only load a new vcpu
75 	 * after a context switch, which imvolves a DSB, so all
76 	 * speculative EL1&0 walks will have already completed.
77 	 * If running NV, the vcpu may transition between vEL1 and
78 	 * vEL2 without a context switch, so make sure we complete
79 	 * those walks before loading a new context.
80 	 */
81 	if (vcpu_has_nv(vcpu))
82 		dsb(nsh);
83 
84 	/*
85 	 * Load guest EL1 and user state
86 	 *
87 	 * We must restore the 32-bit state before the sysregs, thanks
88 	 * to erratum #852523 (Cortex-A57) or #853709 (Cortex-A72).
89 	 */
90 	__sysreg32_restore_state(vcpu);
91 	__sysreg_restore_user_state(guest_ctxt);
92 	__sysreg_restore_el1_state(guest_ctxt);
93 
94 	vcpu_set_flag(vcpu, SYSREGS_ON_CPU);
95 
96 	activate_traps_vhe_load(vcpu);
97 }
98 
99 /**
100  * kvm_vcpu_put_sysregs_vhe - Restore host system registers to the physical CPU
101  *
102  * @vcpu: The VCPU pointer
103  *
104  * Save guest system registers that do not affect the host's execution, for
105  * example EL1 system registers on a VHE system where the host kernel
106  * runs at EL2.  This function is called from KVM's vcpu_put() function
107  * and deferring saving system register state until we're no longer running the
108  * VCPU avoids having to save them on every exit from the VM.
109  */
kvm_vcpu_put_sysregs_vhe(struct kvm_vcpu * vcpu)110 void kvm_vcpu_put_sysregs_vhe(struct kvm_vcpu *vcpu)
111 {
112 	struct kvm_cpu_context *guest_ctxt = &vcpu->arch.ctxt;
113 	struct kvm_cpu_context *host_ctxt;
114 
115 	host_ctxt = &this_cpu_ptr(&kvm_host_data)->host_ctxt;
116 	deactivate_traps_vhe_put(vcpu);
117 
118 	__sysreg_save_el1_state(guest_ctxt);
119 	__sysreg_save_user_state(guest_ctxt);
120 	__sysreg32_save_state(vcpu);
121 
122 	/* Restore host user state */
123 	__sysreg_restore_user_state(host_ctxt);
124 
125 	vcpu_clear_flag(vcpu, SYSREGS_ON_CPU);
126 }
127