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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - arch/arm64/kvm/debug.c
2 * Debug and Guest Debug support
4 * Copyright (C) 2015 - Linaro Ltd
5 * Author: Alex Bennée <alex.bennee@linaro.org>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
20 #include <linux/kvm_host.h>
21 #include <linux/hw_breakpoint.h>
23 #include <asm/debug-monitors.h>
24 #include <asm/kvm_asm.h>
25 #include <asm/kvm_arm.h>
26 #include <asm/kvm_emulate.h>
30 /* These are the bits of MDSCR_EL1 we may manipulate */
31 #define MDSCR_EL1_DEBUG_MASK (DBG_MDSCR_SS | \
35 static DEFINE_PER_CPU(u32
, mdcr_el2
);
38 * save/restore_guest_debug_regs
40 * For some debug operations we need to tweak some guest registers. As
41 * a result we need to save the state of those registers before we
42 * make those modifications.
44 * Guest access to MDSCR_EL1 is trapped by the hypervisor and handled
45 * after we have restored the preserved value to the main context.
47 static void save_guest_debug_regs(struct kvm_vcpu
*vcpu
)
49 vcpu
->arch
.guest_debug_preserved
.mdscr_el1
= vcpu_sys_reg(vcpu
, MDSCR_EL1
);
51 trace_kvm_arm_set_dreg32("Saved MDSCR_EL1",
52 vcpu
->arch
.guest_debug_preserved
.mdscr_el1
);
55 static void restore_guest_debug_regs(struct kvm_vcpu
*vcpu
)
57 vcpu_sys_reg(vcpu
, MDSCR_EL1
) = vcpu
->arch
.guest_debug_preserved
.mdscr_el1
;
59 trace_kvm_arm_set_dreg32("Restored MDSCR_EL1",
60 vcpu_sys_reg(vcpu
, MDSCR_EL1
));
64 * kvm_arm_init_debug - grab what we need for debug
66 * Currently the sole task of this function is to retrieve the initial
67 * value of mdcr_el2 so we can preserve MDCR_EL2.HPMN which has
68 * presumably been set-up by some knowledgeable bootcode.
70 * It is called once per-cpu during CPU hyp initialisation.
73 void kvm_arm_init_debug(void)
75 __this_cpu_write(mdcr_el2
, kvm_call_hyp(__kvm_get_mdcr_el2
));
79 * kvm_arm_reset_debug_ptr - reset the debug ptr to point to the vcpu state
82 void kvm_arm_reset_debug_ptr(struct kvm_vcpu
*vcpu
)
84 vcpu
->arch
.debug_ptr
= &vcpu
->arch
.vcpu_debug_state
;
88 * kvm_arm_setup_debug - set up debug related stuff
90 * @vcpu: the vcpu pointer
92 * This is called before each entry into the hypervisor to setup any
93 * debug related registers. Currently this just ensures we will trap
95 * - Performance monitors (MDCR_EL2_TPM/MDCR_EL2_TPMCR)
96 * - Debug ROM Address (MDCR_EL2_TDRA)
97 * - OS related registers (MDCR_EL2_TDOSA)
98 * - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB)
100 * Additionally, KVM only traps guest accesses to the debug registers if
101 * the guest is not actively using them (see the KVM_ARM64_DEBUG_DIRTY
102 * flag on vcpu->arch.debug_flags). Since the guest must not interfere
103 * with the hardware state when debugging the guest, we must ensure that
104 * trapping is enabled whenever we are debugging the guest using the
108 void kvm_arm_setup_debug(struct kvm_vcpu
*vcpu
)
110 bool trap_debug
= !(vcpu
->arch
.debug_flags
& KVM_ARM64_DEBUG_DIRTY
);
112 trace_kvm_arm_setup_debug(vcpu
, vcpu
->guest_debug
);
115 * This also clears MDCR_EL2_E2PB_MASK to disable guest access
116 * to the profiling buffer.
118 vcpu
->arch
.mdcr_el2
= __this_cpu_read(mdcr_el2
) & MDCR_EL2_HPMN_MASK
;
119 vcpu
->arch
.mdcr_el2
|= (MDCR_EL2_TPM
|
125 /* Is Guest debugging in effect? */
126 if (vcpu
->guest_debug
) {
127 /* Route all software debug exceptions to EL2 */
128 vcpu
->arch
.mdcr_el2
|= MDCR_EL2_TDE
;
130 /* Save guest debug state */
131 save_guest_debug_regs(vcpu
);
134 * Single Step (ARM ARM D2.12.3 The software step state
137 * If we are doing Single Step we need to manipulate
138 * the guest's MDSCR_EL1.SS and PSTATE.SS. Once the
139 * step has occurred the hypervisor will trap the
140 * debug exception and we return to userspace.
142 * If the guest attempts to single step its userspace
143 * we would have to deal with a trapped exception
144 * while in the guest kernel. Because this would be
145 * hard to unwind we suppress the guest's ability to
146 * do so by masking MDSCR_EL.SS.
148 * This confuses guest debuggers which use
149 * single-step behind the scenes but everything
150 * returns to normal once the host is no longer
151 * debugging the system.
153 if (vcpu
->guest_debug
& KVM_GUESTDBG_SINGLESTEP
) {
154 *vcpu_cpsr(vcpu
) |= DBG_SPSR_SS
;
155 vcpu_sys_reg(vcpu
, MDSCR_EL1
) |= DBG_MDSCR_SS
;
157 vcpu_sys_reg(vcpu
, MDSCR_EL1
) &= ~DBG_MDSCR_SS
;
160 trace_kvm_arm_set_dreg32("SPSR_EL2", *vcpu_cpsr(vcpu
));
163 * HW Breakpoints and watchpoints
165 * We simply switch the debug_ptr to point to our new
166 * external_debug_state which has been populated by the
167 * debug ioctl. The existing KVM_ARM64_DEBUG_DIRTY
168 * mechanism ensures the registers are updated on the
171 if (vcpu
->guest_debug
& KVM_GUESTDBG_USE_HW
) {
172 /* Enable breakpoints/watchpoints */
173 vcpu_sys_reg(vcpu
, MDSCR_EL1
) |= DBG_MDSCR_MDE
;
175 vcpu
->arch
.debug_ptr
= &vcpu
->arch
.external_debug_state
;
176 vcpu
->arch
.debug_flags
|= KVM_ARM64_DEBUG_DIRTY
;
179 trace_kvm_arm_set_regset("BKPTS", get_num_brps(),
180 &vcpu
->arch
.debug_ptr
->dbg_bcr
[0],
181 &vcpu
->arch
.debug_ptr
->dbg_bvr
[0]);
183 trace_kvm_arm_set_regset("WAPTS", get_num_wrps(),
184 &vcpu
->arch
.debug_ptr
->dbg_wcr
[0],
185 &vcpu
->arch
.debug_ptr
->dbg_wvr
[0]);
189 BUG_ON(!vcpu
->guest_debug
&&
190 vcpu
->arch
.debug_ptr
!= &vcpu
->arch
.vcpu_debug_state
);
192 /* Trap debug register access */
194 vcpu
->arch
.mdcr_el2
|= MDCR_EL2_TDA
;
196 trace_kvm_arm_set_dreg32("MDCR_EL2", vcpu
->arch
.mdcr_el2
);
197 trace_kvm_arm_set_dreg32("MDSCR_EL1", vcpu_sys_reg(vcpu
, MDSCR_EL1
));
200 void kvm_arm_clear_debug(struct kvm_vcpu
*vcpu
)
202 trace_kvm_arm_clear_debug(vcpu
->guest_debug
);
204 if (vcpu
->guest_debug
) {
205 restore_guest_debug_regs(vcpu
);
208 * If we were using HW debug we need to restore the
209 * debug_ptr to the guest debug state.
211 if (vcpu
->guest_debug
& KVM_GUESTDBG_USE_HW
) {
212 kvm_arm_reset_debug_ptr(vcpu
);
214 trace_kvm_arm_set_regset("BKPTS", get_num_brps(),
215 &vcpu
->arch
.debug_ptr
->dbg_bcr
[0],
216 &vcpu
->arch
.debug_ptr
->dbg_bvr
[0]);
218 trace_kvm_arm_set_regset("WAPTS", get_num_wrps(),
219 &vcpu
->arch
.debug_ptr
->dbg_wcr
[0],
220 &vcpu
->arch
.debug_ptr
->dbg_wvr
[0]);