Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
KVM: arm64: Add PKVM_DISABLE_STAGE2_ON_PANIC
On NVHE_EL2_DEBUG, when using pKVM, the host stage-2 is relaxed to grant
the kernel access to the stacktrace, hypervisor bug table and text to
symbolize addresses. This is unsafe for production. In preparation for
adding more debug options to NVHE_EL2_DEBUG, decouple the stage-2
relaxation into a separate option.
While at it, rename PROTECTED_NVHE_STACKTRACE into PKVM_STACKTRACE,
following the same naming scheme as PKVM_DISABLE_STAGE2_ON_PANIC.
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Link: https://patch.msgid.link/20260309162516.2623589-20-vdonnefort@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
authored by
Vincent Donnefort
and committed by
Marc Zyngier
9019e82c
a717943d
+48
-32
+39
-23
arch/arm64/kvm/Kconfig
+39
-23
arch/arm64/kvm/Kconfig
···
42
42
43
43
If unsure, say N.
44
44
45
-
config NVHE_EL2_DEBUG
46
-
bool "Debug mode for non-VHE EL2 object"
47
-
depends on KVM
48
-
help
49
-
Say Y here to enable the debug mode for the non-VHE KVM EL2 object.
50
-
Failure reports will BUG() in the hypervisor. This is intended for
51
-
local EL2 hypervisor development.
52
-
53
-
If unsure, say N.
54
-
55
-
config PROTECTED_NVHE_STACKTRACE
56
-
bool "Protected KVM hypervisor stacktraces"
57
-
depends on NVHE_EL2_DEBUG
58
-
default n
59
-
help
60
-
Say Y here to enable pKVM hypervisor stacktraces on hyp_panic()
61
-
62
-
If using protected nVHE mode, but cannot afford the associated
63
-
memory cost (less than 0.75 page per CPU) of pKVM stacktraces,
64
-
say N.
65
-
66
-
If unsure, or not using protected nVHE (pKVM), say N.
45
+
if KVM
67
46
68
47
config PTDUMP_STAGE2_DEBUGFS
69
48
bool "Present the stage-2 pagetables to debugfs"
70
-
depends on KVM
71
49
depends on DEBUG_KERNEL
72
50
depends on DEBUG_FS
73
51
depends on ARCH_HAS_PTDUMP
···
60
82
61
83
If in doubt, say N.
62
84
85
+
config NVHE_EL2_DEBUG
86
+
bool "Debug mode for non-VHE EL2 object"
87
+
default n
88
+
help
89
+
Say Y here to enable the debug mode for the non-VHE KVM EL2 object.
90
+
Failure reports will BUG() in the hypervisor. This is intended for
91
+
local EL2 hypervisor development.
92
+
93
+
If unsure, say N.
94
+
95
+
if NVHE_EL2_DEBUG
96
+
97
+
config PKVM_DISABLE_STAGE2_ON_PANIC
98
+
bool "Disable the host stage-2 on panic"
99
+
default n
100
+
help
101
+
Relax the host stage-2 on hypervisor panic to allow the kernel to
102
+
unwind and symbolize the hypervisor stacktrace. This however tampers
103
+
the system security. This is intended for local EL2 hypervisor
104
+
development.
105
+
106
+
If unsure, say N.
107
+
108
+
config PKVM_STACKTRACE
109
+
bool "Protected KVM hypervisor stacktraces"
110
+
depends on PKVM_DISABLE_STAGE2_ON_PANIC
111
+
default y
112
+
help
113
+
Say Y here to enable pKVM hypervisor stacktraces on hyp_panic()
114
+
115
+
If using protected nVHE mode, but cannot afford the associated
116
+
memory cost (less than 0.75 page per CPU) of pKVM stacktraces,
117
+
say N.
118
+
119
+
If unsure, or not using protected nVHE (pKVM), say N.
120
+
121
+
endif # NVHE_EL2_DEBUG
122
+
endif # KVM
63
123
endif # VIRTUALIZATION
+1
-1
arch/arm64/kvm/handle_exit.c
+1
-1
arch/arm64/kvm/handle_exit.c
···
539
539
540
540
/* All hyp bugs, including warnings, are treated as fatal. */
541
541
if (!is_protected_kvm_enabled() ||
542
-
IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) {
542
+
IS_ENABLED(CONFIG_PKVM_DISABLE_STAGE2_ON_PANIC)) {
543
543
struct bug_entry *bug = find_bug(elr_in_kimg);
544
544
545
545
if (bug)
+1
-1
arch/arm64/kvm/hyp/nvhe/host.S
+1
-1
arch/arm64/kvm/hyp/nvhe/host.S
+3
-3
arch/arm64/kvm/hyp/nvhe/stacktrace.c
+3
-3
arch/arm64/kvm/hyp/nvhe/stacktrace.c
···
34
34
stacktrace_info->pc = pc;
35
35
}
36
36
37
-
#ifdef CONFIG_PROTECTED_NVHE_STACKTRACE
37
+
#ifdef CONFIG_PKVM_STACKTRACE
38
38
#include <asm/stacktrace/nvhe.h>
39
39
40
40
DEFINE_PER_CPU(unsigned long [NVHE_STACKTRACE_SIZE/sizeof(long)], pkvm_stacktrace);
···
134
134
135
135
unwind(&state, pkvm_save_backtrace_entry, &idx);
136
136
}
137
-
#else /* !CONFIG_PROTECTED_NVHE_STACKTRACE */
137
+
#else /* !CONFIG_PKVM_STACKTRACE */
138
138
static void pkvm_save_backtrace(unsigned long fp, unsigned long pc)
139
139
{
140
140
}
141
-
#endif /* CONFIG_PROTECTED_NVHE_STACKTRACE */
141
+
#endif /* CONFIG_PKVM_STACKTRACE */
142
142
143
143
/*
144
144
* kvm_nvhe_prepare_backtrace - prepare to dump the nVHE backtrace
+4
-4
arch/arm64/kvm/stacktrace.c
+4
-4
arch/arm64/kvm/stacktrace.c
···
197
197
kvm_nvhe_dump_backtrace_end();
198
198
}
199
199
200
-
#ifdef CONFIG_PROTECTED_NVHE_STACKTRACE
200
+
#ifdef CONFIG_PKVM_STACKTRACE
201
201
DECLARE_KVM_NVHE_PER_CPU(unsigned long [NVHE_STACKTRACE_SIZE/sizeof(long)],
202
202
pkvm_stacktrace);
203
203
···
225
225
kvm_nvhe_dump_backtrace_entry((void *)hyp_offset, stacktrace[i]);
226
226
kvm_nvhe_dump_backtrace_end();
227
227
}
228
-
#else /* !CONFIG_PROTECTED_NVHE_STACKTRACE */
228
+
#else /* !CONFIG_PKVM_STACKTRACE */
229
229
static void pkvm_dump_backtrace(unsigned long hyp_offset)
230
230
{
231
-
kvm_err("Cannot dump pKVM nVHE stacktrace: !CONFIG_PROTECTED_NVHE_STACKTRACE\n");
231
+
kvm_err("Cannot dump pKVM nVHE stacktrace: !CONFIG_PKVM_STACKTRACE\n");
232
232
}
233
-
#endif /* CONFIG_PROTECTED_NVHE_STACKTRACE */
233
+
#endif /* CONFIG_PKVM_STACKTRACE */
234
234
235
235
/*
236
236
* kvm_nvhe_dump_backtrace - Dump KVM nVHE hypervisor backtrace.