* [PATCH v2 0/5] KVM nVHE Hypervisor stack unwinder
@ 2022-05-02 19:12 Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 1/5] KVM: arm64: Factor out common stack unwinding logic Kalesh Singh
` (4 more replies)
0 siblings, 5 replies; 9+ messages in thread
From: Kalesh Singh @ 2022-05-02 19:12 UTC (permalink / raw)
Cc: mark.rutland, broonie, will, maz, qperret, tabba, surenb,
kernel-team, Kalesh Singh, James Morse, Alexandru Elisei,
Suzuki K Poulose, Catalin Marinas, Masami Hiramatsu,
Alexei Starovoitov, Peter Collingbourne,
Madhavan T. Venkataraman, Andrew Jones, Zenghui Yu, Keir Fraser,
Kefeng Wang, linux-arm-kernel, kvmarm, linux-kernel
Hi all,
This v2 of the nVHE hypervisor stack unwinder. The previous version was
posted at:
v1: https://lore.kernel.org/lkml/20220427184716.1949239-1-kaleshsingh@google.com/
The series is based on arm64 for-next/core and is also dependent on
kvm-arm64/hyp-stack-guard [1].
The main changes in this version is splitting some patches into more
incremental changes, per Mark Brown
The relevant parts of the previous cover letter are copied below for
convenience.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=kvm-arm64/hyp-stack-guard
Thanks,
Kalesh
-------
This new version of the unwinder splits the unwinding and dumping
of the stack between the hypervisor and host:
- The hypervisor unwinds its stack and dumps the address entries
into a page shared with the host.
- The host then symnolizes and prints the hyp stacktrace from
the shared page.
The new approach doesn't depend on CONFIG_NVHE_EL2_DEBUG,
and allows dumping hyp stacktraces in prodcution environments
(!CONFIG_NVHE_EL2_DEBUG).
arm64/kernel/stacktrace.c is compiled twice: stacktrace.o for the
host kernel and stacktrace.nvhe.o for the hypervisor. This allows
reusing most of the host unwinding logic in the nVHE hypervisor.
Kalesh Singh (5):
KVM: arm64: Factor out common stack unwinding logic
KVM: arm64: Compile stacktrace.nvhe.o
KVM: arm64: Add hypervisor overflow stack
KVM: arm64: Allocate shared stacktrace pages
KVM: arm64: Unwind and dump nVHE hypervisor stacktrace
arch/arm64/include/asm/kvm_asm.h | 1 +
arch/arm64/include/asm/stacktrace.h | 58 +++++++++--
arch/arm64/kernel/stacktrace.c | 151 +++++++++++++++++++++++-----
arch/arm64/kvm/arm.c | 34 +++++++
arch/arm64/kvm/handle_exit.c | 4 +
arch/arm64/kvm/hyp/nvhe/Makefile | 3 +-
arch/arm64/kvm/hyp/nvhe/host.S | 9 +-
arch/arm64/kvm/hyp/nvhe/setup.c | 11 ++
arch/arm64/kvm/hyp/nvhe/switch.c | 4 +
9 files changed, 231 insertions(+), 44 deletions(-)
--
2.36.0.464.gb9c8b46e94-goog
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v2 1/5] KVM: arm64: Factor out common stack unwinding logic
2022-05-02 19:12 [PATCH v2 0/5] KVM nVHE Hypervisor stack unwinder Kalesh Singh
@ 2022-05-02 19:12 ` Kalesh Singh
2022-05-04 13:41 ` Mark Brown
2022-05-02 19:12 ` [PATCH v2 2/5] KVM: arm64: Compile stacktrace.nvhe.o Kalesh Singh
` (3 subsequent siblings)
4 siblings, 1 reply; 9+ messages in thread
From: Kalesh Singh @ 2022-05-02 19:12 UTC (permalink / raw)
Cc: mark.rutland, broonie, will, maz, qperret, tabba, surenb,
kernel-team, Kalesh Singh, James Morse, Alexandru Elisei,
Suzuki K Poulose, Catalin Marinas, Masami Hiramatsu,
Peter Collingbourne, Alexei Starovoitov,
Madhavan T. Venkataraman, Andrew Jones, Keir Fraser, Marco Elver,
Kefeng Wang, Zenghui Yu, Ard Biesheuvel, linux-arm-kernel,
kvmarm, linux-kernel
Factor out the stack unwinding logic common to both the host kernel and
the nVHE hypersivor into __unwind_next(). This allows for reuse in the
nVHE hypervisor stack unwinding (later in this series).
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
arch/arm64/kernel/stacktrace.c | 36 +++++++++++++++++++++++-----------
1 file changed, 25 insertions(+), 11 deletions(-)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 0467cb79f080..ee60c279511c 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -81,23 +81,19 @@ NOKPROBE_SYMBOL(unwind_init);
* records (e.g. a cycle), determined based on the location and fp value of A
* and the location (but not the fp value) of B.
*/
-static int notrace unwind_next(struct task_struct *tsk,
- struct unwind_state *state)
+static int notrace __unwind_next(struct task_struct *tsk,
+ struct unwind_state *state,
+ struct stack_info *info)
{
unsigned long fp = state->fp;
- struct stack_info info;
-
- /* Final frame; nothing to unwind */
- if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)
- return -ENOENT;
if (fp & 0x7)
return -EINVAL;
- if (!on_accessible_stack(tsk, fp, 16, &info))
+ if (!on_accessible_stack(tsk, fp, 16, info))
return -EINVAL;
- if (test_bit(info.type, state->stacks_done))
+ if (test_bit(info->type, state->stacks_done))
return -EINVAL;
/*
@@ -113,7 +109,7 @@ static int notrace unwind_next(struct task_struct *tsk,
* stack to another, it's never valid to unwind back to that first
* stack.
*/
- if (info.type == state->prev_type) {
+ if (info->type == state->prev_type) {
if (fp <= state->prev_fp)
return -EINVAL;
} else {
@@ -127,7 +123,25 @@ static int notrace unwind_next(struct task_struct *tsk,
state->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
state->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8));
state->prev_fp = fp;
- state->prev_type = info.type;
+ state->prev_type = info->type;
+
+ return 0;
+}
+NOKPROBE_SYMBOL(__unwind_next);
+
+static int notrace unwind_next(struct task_struct *tsk,
+ struct unwind_state *state)
+{
+ struct stack_info info;
+ int err;
+
+ /* Final frame; nothing to unwind */
+ if (state->fp == (unsigned long)task_pt_regs(tsk)->stackframe)
+ return -ENOENT;
+
+ err = __unwind_next(tsk, state, &info);
+ if (err)
+ return err;
state->pc = ptrauth_strip_insn_pac(state->pc);
--
2.36.0.464.gb9c8b46e94-goog
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v2 2/5] KVM: arm64: Compile stacktrace.nvhe.o
2022-05-02 19:12 [PATCH v2 0/5] KVM nVHE Hypervisor stack unwinder Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 1/5] KVM: arm64: Factor out common stack unwinding logic Kalesh Singh
@ 2022-05-02 19:12 ` Kalesh Singh
2022-05-04 14:16 ` Mark Brown
2022-05-02 19:12 ` [PATCH v2 3/5] KVM: arm64: Add hypervisor overflow stack Kalesh Singh
` (2 subsequent siblings)
4 siblings, 1 reply; 9+ messages in thread
From: Kalesh Singh @ 2022-05-02 19:12 UTC (permalink / raw)
Cc: mark.rutland, broonie, will, maz, qperret, tabba, surenb,
kernel-team, Kalesh Singh, James Morse, Alexandru Elisei,
Suzuki K Poulose, Catalin Marinas, Masami Hiramatsu,
Peter Collingbourne, Alexei Starovoitov,
Madhavan T. Venkataraman, Andrew Jones, Marco Elver, Kefeng Wang,
Keir Fraser, Zenghui Yu, linux-arm-kernel, kvmarm, linux-kernel
Recompile stack unwinding code for use with the nVHE hypervisor. This is
a preparatory patch that will allow reusing most of the kernel unwinding
logic in the nVHE hypervisor.
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
Changes in v2:
- Split out refactoring of common unwinding logic into a separate patch,
per Mark Brown
arch/arm64/include/asm/stacktrace.h | 18 +++++++++-----
arch/arm64/kernel/stacktrace.c | 37 ++++++++++++++++-------------
arch/arm64/kvm/hyp/nvhe/Makefile | 3 ++-
3 files changed, 35 insertions(+), 23 deletions(-)
diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
index aec9315bf156..f5af9a94c5a6 100644
--- a/arch/arm64/include/asm/stacktrace.h
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -16,12 +16,14 @@
#include <asm/sdei.h>
enum stack_type {
- STACK_TYPE_UNKNOWN,
+#ifndef __KVM_NVHE_HYPERVISOR__
STACK_TYPE_TASK,
STACK_TYPE_IRQ,
STACK_TYPE_OVERFLOW,
STACK_TYPE_SDEI_NORMAL,
STACK_TYPE_SDEI_CRITICAL,
+#endif /* !__KVM_NVHE_HYPERVISOR__ */
+ STACK_TYPE_UNKNOWN,
__NR_STACK_TYPES
};
@@ -31,11 +33,6 @@ struct stack_info {
enum stack_type type;
};
-extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
- const char *loglvl);
-
-DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);
-
static inline bool on_stack(unsigned long sp, unsigned long size,
unsigned long low, unsigned long high,
enum stack_type type, struct stack_info *info)
@@ -54,6 +51,12 @@ static inline bool on_stack(unsigned long sp, unsigned long size,
return true;
}
+#ifndef __KVM_NVHE_HYPERVISOR__
+extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
+ const char *loglvl);
+
+DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);
+
static inline bool on_irq_stack(unsigned long sp, unsigned long size,
struct stack_info *info)
{
@@ -88,6 +91,7 @@ static inline bool on_overflow_stack(unsigned long sp, unsigned long size,
static inline bool on_overflow_stack(unsigned long sp, unsigned long size,
struct stack_info *info) { return false; }
#endif
+#endif /* !__KVM_NVHE_HYPERVISOR__ */
/*
@@ -101,6 +105,7 @@ static inline bool on_accessible_stack(const struct task_struct *tsk,
if (info)
info->type = STACK_TYPE_UNKNOWN;
+#ifndef __KVM_NVHE_HYPERVISOR__
if (on_task_stack(tsk, sp, size, info))
return true;
if (tsk != current || preemptible())
@@ -111,6 +116,7 @@ static inline bool on_accessible_stack(const struct task_struct *tsk,
return true;
if (on_sdei_stack(sp, size, info))
return true;
+#endif /* !__KVM_NVHE_HYPERVISOR__ */
return false;
}
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index ee60c279511c..a84e38d41d38 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -129,6 +129,26 @@ static int notrace __unwind_next(struct task_struct *tsk,
}
NOKPROBE_SYMBOL(__unwind_next);
+static int notrace unwind_next(struct task_struct *tsk,
+ struct unwind_state *state);
+
+static void notrace unwind(struct task_struct *tsk,
+ struct unwind_state *state,
+ stack_trace_consume_fn consume_entry, void *cookie)
+{
+ while (1) {
+ int ret;
+
+ if (!consume_entry(cookie, state->pc))
+ break;
+ ret = unwind_next(tsk, state);
+ if (ret < 0)
+ break;
+ }
+}
+NOKPROBE_SYMBOL(unwind);
+
+#ifndef __KVM_NVHE_HYPERVISOR__
static int notrace unwind_next(struct task_struct *tsk,
struct unwind_state *state)
{
@@ -171,22 +191,6 @@ static int notrace unwind_next(struct task_struct *tsk,
}
NOKPROBE_SYMBOL(unwind_next);
-static void notrace unwind(struct task_struct *tsk,
- struct unwind_state *state,
- stack_trace_consume_fn consume_entry, void *cookie)
-{
- while (1) {
- int ret;
-
- if (!consume_entry(cookie, state->pc))
- break;
- ret = unwind_next(tsk, state);
- if (ret < 0)
- break;
- }
-}
-NOKPROBE_SYMBOL(unwind);
-
static bool dump_backtrace_entry(void *arg, unsigned long where)
{
char *loglvl = arg;
@@ -238,3 +242,4 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
unwind(task, &state, consume_entry, cookie);
}
+#endif /* !__KVM_NVHE_HYPERVISOR__ */
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index f9fe4dc21b1f..c0ff0d6fc403 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -14,7 +14,8 @@ lib-objs := $(addprefix ../../../lib/, $(lib-objs))
obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
hyp-main.o hyp-smp.o psci-relay.o early_alloc.o page_alloc.o \
- cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o
+ cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o \
+ ../../../kernel/stacktrace.o
obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
obj-$(CONFIG_DEBUG_LIST) += list_debug.o
--
2.36.0.464.gb9c8b46e94-goog
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v2 3/5] KVM: arm64: Add hypervisor overflow stack
2022-05-02 19:12 [PATCH v2 0/5] KVM nVHE Hypervisor stack unwinder Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 1/5] KVM: arm64: Factor out common stack unwinding logic Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 2/5] KVM: arm64: Compile stacktrace.nvhe.o Kalesh Singh
@ 2022-05-02 19:12 ` Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 4/5] KVM: arm64: Allocate shared stacktrace pages Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 5/5] KVM: arm64: Unwind and dump nVHE hypervisor stacktrace Kalesh Singh
4 siblings, 0 replies; 9+ messages in thread
From: Kalesh Singh @ 2022-05-02 19:12 UTC (permalink / raw)
Cc: mark.rutland, broonie, will, maz, qperret, tabba, surenb,
kernel-team, Kalesh Singh, James Morse, Alexandru Elisei,
Suzuki K Poulose, Catalin Marinas, Masami Hiramatsu,
Peter Collingbourne, Alexei Starovoitov,
Madhavan T. Venkataraman, Andrew Jones, Marco Elver, Kefeng Wang,
Keir Fraser, Zenghui Yu, linux-arm-kernel, kvmarm, linux-kernel
Allocate and switch to 16-byte aligned secondary stack on overflow. This
provides us stack space to better handle overflows; and is used in
a subsequent patch to dump the hypervisor stacktrace.
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
arch/arm64/kernel/stacktrace.c | 3 +++
arch/arm64/kvm/hyp/nvhe/host.S | 9 ++-------
2 files changed, 5 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index a84e38d41d38..f346b4c66f1c 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -242,4 +242,7 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
unwind(task, &state, consume_entry, cookie);
}
+#else /* __KVM_NVHE_HYPERVISOR__ */
+DEFINE_PER_CPU(unsigned long [PAGE_SIZE/sizeof(long)], overflow_stack)
+ __aligned(16);
#endif /* !__KVM_NVHE_HYPERVISOR__ */
diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index 09b5254fb497..1cd2de4f039e 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -179,13 +179,8 @@ SYM_FUNC_END(__host_hvc)
b hyp_panic
.L__hyp_sp_overflow\@:
- /*
- * Reset SP to the top of the stack, to allow handling the hyp_panic.
- * This corrupts the stack but is ok, since we won't be attempting
- * any unwinding here.
- */
- ldr_this_cpu x0, kvm_init_params + NVHE_INIT_STACK_HYP_VA, x1
- mov sp, x0
+ /* Switch to the overflow stack */
+ adr_this_cpu sp, overflow_stack + PAGE_SIZE, x0
b hyp_panic_bad_stack
ASM_BUG()
--
2.36.0.464.gb9c8b46e94-goog
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v2 4/5] KVM: arm64: Allocate shared stacktrace pages
2022-05-02 19:12 [PATCH v2 0/5] KVM nVHE Hypervisor stack unwinder Kalesh Singh
` (2 preceding siblings ...)
2022-05-02 19:12 ` [PATCH v2 3/5] KVM: arm64: Add hypervisor overflow stack Kalesh Singh
@ 2022-05-02 19:12 ` Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 5/5] KVM: arm64: Unwind and dump nVHE hypervisor stacktrace Kalesh Singh
4 siblings, 0 replies; 9+ messages in thread
From: Kalesh Singh @ 2022-05-02 19:12 UTC (permalink / raw)
Cc: mark.rutland, broonie, will, maz, qperret, tabba, surenb,
kernel-team, Kalesh Singh, James Morse, Alexandru Elisei,
Suzuki K Poulose, Catalin Marinas, Masami Hiramatsu,
Peter Collingbourne, Alexei Starovoitov,
Madhavan T. Venkataraman, Andrew Jones, Marco Elver, Zenghui Yu,
Kefeng Wang, Keir Fraser, linux-arm-kernel, kvmarm, linux-kernel
The nVHE hypervisor can use this shared area to dump its stacktrace
addresses on hyp_panic(). Symbolization and printing the stacktrace can
then be handled by the host in EL1 (done in a later patch in this series).
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
arch/arm64/include/asm/kvm_asm.h | 1 +
arch/arm64/kvm/arm.c | 34 ++++++++++++++++++++++++++++++++
arch/arm64/kvm/hyp/nvhe/setup.c | 11 +++++++++++
3 files changed, 46 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 2e277f2ed671..ad31ac68264f 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -174,6 +174,7 @@ struct kvm_nvhe_init_params {
unsigned long hcr_el2;
unsigned long vttbr;
unsigned long vtcr;
+ unsigned long stacktrace_hyp_va;
};
/* Translate a kernel address @ptr into its equivalent linear mapping */
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index d300def44f5c..26005182da20 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -50,6 +50,7 @@ DEFINE_STATIC_KEY_FALSE(kvm_protected_mode_initialized);
DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector);
static DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
+DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stacktrace_page);
unsigned long kvm_arm_hyp_percpu_base[NR_CPUS];
DECLARE_KVM_NVHE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
@@ -1484,6 +1485,7 @@ static void cpu_prepare_hyp_mode(int cpu)
tcr |= (idmap_t0sz & GENMASK(TCR_TxSZ_WIDTH - 1, 0)) << TCR_T0SZ_OFFSET;
params->tcr_el2 = tcr;
+ params->stacktrace_hyp_va = kern_hyp_va(per_cpu(kvm_arm_hyp_stacktrace_page, cpu));
params->pgd_pa = kvm_mmu_get_httbr();
if (is_protected_kvm_enabled())
params->hcr_el2 = HCR_HOST_NVHE_PROTECTED_FLAGS;
@@ -1777,6 +1779,7 @@ static void teardown_hyp_mode(void)
free_hyp_pgds();
for_each_possible_cpu(cpu) {
free_page(per_cpu(kvm_arm_hyp_stack_page, cpu));
+ free_page(per_cpu(kvm_arm_hyp_stacktrace_page, cpu));
free_pages(kvm_arm_hyp_percpu_base[cpu], nvhe_percpu_order());
}
}
@@ -1868,6 +1871,23 @@ static int init_hyp_mode(void)
per_cpu(kvm_arm_hyp_stack_page, cpu) = stack_page;
}
+ /*
+ * Allocate stacktrace pages for Hypervisor-mode.
+ * This is used by the hypervisor to share its stacktrace
+ * with the host on a hyp_panic().
+ */
+ for_each_possible_cpu(cpu) {
+ unsigned long stacktrace_page;
+
+ stacktrace_page = __get_free_page(GFP_KERNEL);
+ if (!stacktrace_page) {
+ err = -ENOMEM;
+ goto out_err;
+ }
+
+ per_cpu(kvm_arm_hyp_stacktrace_page, cpu) = stacktrace_page;
+ }
+
/*
* Allocate and initialize pages for Hypervisor-mode percpu regions.
*/
@@ -1975,6 +1995,20 @@ static int init_hyp_mode(void)
params->stack_hyp_va = hyp_addr + (2 * PAGE_SIZE);
}
+ /*
+ * Map the hyp stacktrace pages.
+ */
+ for_each_possible_cpu(cpu) {
+ char *stacktrace_page = (char *)per_cpu(kvm_arm_hyp_stacktrace_page, cpu);
+
+ err = create_hyp_mappings(stacktrace_page, stacktrace_page + PAGE_SIZE,
+ PAGE_HYP);
+ if (err) {
+ kvm_err("Cannot map hyp stacktrace page\n");
+ goto out_err;
+ }
+ }
+
for_each_possible_cpu(cpu) {
char *percpu_begin = (char *)kvm_arm_hyp_percpu_base[cpu];
char *percpu_end = percpu_begin + nvhe_percpu_size();
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index e8d4ea2fcfa0..9b81bf2d40d7 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -135,6 +135,17 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
/* Update stack_hyp_va to end of the stack's private VA range */
params->stack_hyp_va = hyp_addr + (2 * PAGE_SIZE);
+
+ /*
+ * Map the stacktrace pages as shared and transfer ownership to
+ * the hypervisor.
+ */
+ prot = pkvm_mkstate(PAGE_HYP, PKVM_PAGE_SHARED_OWNED);
+ start = (void *)params->stacktrace_hyp_va;
+ end = start + PAGE_SIZE;
+ ret = pkvm_create_mappings(start, end, prot);
+ if (ret)
+ return ret;
}
/*
--
2.36.0.464.gb9c8b46e94-goog
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v2 5/5] KVM: arm64: Unwind and dump nVHE hypervisor stacktrace
2022-05-02 19:12 [PATCH v2 0/5] KVM nVHE Hypervisor stack unwinder Kalesh Singh
` (3 preceding siblings ...)
2022-05-02 19:12 ` [PATCH v2 4/5] KVM: arm64: Allocate shared stacktrace pages Kalesh Singh
@ 2022-05-02 19:12 ` Kalesh Singh
4 siblings, 0 replies; 9+ messages in thread
From: Kalesh Singh @ 2022-05-02 19:12 UTC (permalink / raw)
Cc: mark.rutland, broonie, will, maz, qperret, tabba, surenb,
kernel-team, Kalesh Singh, James Morse, Alexandru Elisei,
Suzuki K Poulose, Catalin Marinas, Masami Hiramatsu,
Alexei Starovoitov, Peter Collingbourne,
Madhavan T. Venkataraman, Andrew Jones, Kefeng Wang, Keir Fraser,
Zenghui Yu, linux-arm-kernel, kvmarm, linux-kernel
On hyp_panic(), the hypervisor dumps the addresses for its stacktrace
entries to a page shared with the host. The host then symbolizes and
prints the hyp stacktrace before panicking itself.
Example stacktrace:
[ 122.051187] kvm [380]: Invalid host exception to nVHE hyp!
[ 122.052467] kvm [380]: nVHE HYP call trace:
[ 122.052814] kvm [380]: [<ffff800008f5b550>] __kvm_nvhe___pkvm_vcpu_init_traps+0x1f0/0x1f0
[ 122.053865] kvm [380]: [<ffff800008f560f0>] __kvm_nvhe_hyp_panic+0x130/0x1c0
[ 122.054367] kvm [380]: [<ffff800008f56190>] __kvm_nvhe___kvm_vcpu_run+0x10/0x10
[ 122.054878] kvm [380]: [<ffff800008f57a40>] __kvm_nvhe_handle___kvm_vcpu_run+0x30/0x50
[ 122.055412] kvm [380]: [<ffff800008f57d2c>] __kvm_nvhe_handle_trap+0xbc/0x160
[ 122.055911] kvm [380]: [<ffff800008f56864>] __kvm_nvhe___host_exit+0x64/0x64
[ 122.056417] kvm [380]: ---- end of nVHE HYP call trace ----
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
---
Changes in v2:
- Add Mark's Reviewed-by tag
arch/arm64/include/asm/stacktrace.h | 42 ++++++++++++++--
arch/arm64/kernel/stacktrace.c | 75 +++++++++++++++++++++++++++++
arch/arm64/kvm/handle_exit.c | 4 ++
arch/arm64/kvm/hyp/nvhe/switch.c | 4 ++
4 files changed, 121 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
index f5af9a94c5a6..3063912107b0 100644
--- a/arch/arm64/include/asm/stacktrace.h
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -5,6 +5,7 @@
#ifndef __ASM_STACKTRACE_H
#define __ASM_STACKTRACE_H
+#include <linux/kvm_host.h>
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
@@ -19,10 +20,12 @@ enum stack_type {
#ifndef __KVM_NVHE_HYPERVISOR__
STACK_TYPE_TASK,
STACK_TYPE_IRQ,
- STACK_TYPE_OVERFLOW,
STACK_TYPE_SDEI_NORMAL,
STACK_TYPE_SDEI_CRITICAL,
+#else /* __KVM_NVHE_HYPERVISOR__ */
+ STACK_TYPE_HYP,
#endif /* !__KVM_NVHE_HYPERVISOR__ */
+ STACK_TYPE_OVERFLOW,
STACK_TYPE_UNKNOWN,
__NR_STACK_TYPES
};
@@ -55,6 +58,9 @@ static inline bool on_stack(unsigned long sp, unsigned long size,
extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
const char *loglvl);
+extern void hyp_dump_backtrace(unsigned long hyp_offset);
+
+DECLARE_PER_CPU(unsigned long, kvm_arm_hyp_stacktrace_page);
DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);
static inline bool on_irq_stack(unsigned long sp, unsigned long size,
@@ -91,8 +97,32 @@ static inline bool on_overflow_stack(unsigned long sp, unsigned long size,
static inline bool on_overflow_stack(unsigned long sp, unsigned long size,
struct stack_info *info) { return false; }
#endif
-#endif /* !__KVM_NVHE_HYPERVISOR__ */
+#else /* __KVM_NVHE_HYPERVISOR__ */
+
+extern void hyp_save_backtrace(void);
+
+DECLARE_PER_CPU(unsigned long [PAGE_SIZE/sizeof(long)], overflow_stack);
+DECLARE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
+
+static inline bool on_overflow_stack(unsigned long sp, unsigned long size,
+ struct stack_info *info)
+{
+ unsigned long low = (unsigned long)this_cpu_ptr(overflow_stack);
+ unsigned long high = low + PAGE_SIZE;
+
+ return on_stack(sp, size, low, high, STACK_TYPE_OVERFLOW, info);
+}
+
+static inline bool on_hyp_stack(unsigned long sp, unsigned long size,
+ struct stack_info *info)
+{
+ struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
+ unsigned long high = params->stack_hyp_va;
+ unsigned long low = high - PAGE_SIZE;
+ return on_stack(sp, size, low, high, STACK_TYPE_HYP, info);
+}
+#endif /* !__KVM_NVHE_HYPERVISOR__ */
/*
* We can only safely access per-cpu stacks from current in a non-preemptible
@@ -105,6 +135,9 @@ static inline bool on_accessible_stack(const struct task_struct *tsk,
if (info)
info->type = STACK_TYPE_UNKNOWN;
+ if (on_overflow_stack(sp, size, info))
+ return true;
+
#ifndef __KVM_NVHE_HYPERVISOR__
if (on_task_stack(tsk, sp, size, info))
return true;
@@ -112,10 +145,11 @@ static inline bool on_accessible_stack(const struct task_struct *tsk,
return false;
if (on_irq_stack(sp, size, info))
return true;
- if (on_overflow_stack(sp, size, info))
- return true;
if (on_sdei_stack(sp, size, info))
return true;
+#else /* __KVM_NVHE_HYPERVISOR__ */
+ if (on_hyp_stack(sp, size, info))
+ return true;
#endif /* !__KVM_NVHE_HYPERVISOR__ */
return false;
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index f346b4c66f1c..c81dea9760ac 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -104,6 +104,7 @@ static int notrace __unwind_next(struct task_struct *tsk,
*
* TASK -> IRQ -> OVERFLOW -> SDEI_NORMAL
* TASK -> SDEI_NORMAL -> SDEI_CRITICAL -> OVERFLOW
+ * HYP -> OVERFLOW
*
* ... but the nesting itself is strict. Once we transition from one
* stack to another, it's never valid to unwind back to that first
@@ -242,7 +243,81 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
unwind(task, &state, consume_entry, cookie);
}
+
+/**
+ * Symbolizes and dumps the hypervisor backtrace from the shared
+ * stacktrace page.
+ */
+noinline notrace void hyp_dump_backtrace(unsigned long hyp_offset)
+{
+ unsigned long *stacktrace_pos =
+ (unsigned long *)*this_cpu_ptr(&kvm_arm_hyp_stacktrace_page);
+ unsigned long va_mask = GENMASK_ULL(vabits_actual - 1, 0);
+ unsigned long pc = *stacktrace_pos++;
+
+ kvm_err("nVHE HYP call trace:\n");
+
+ while (pc) {
+ pc &= va_mask; /* Mask tags */
+ pc += hyp_offset; /* Convert to kern addr */
+ kvm_err("[<%016lx>] %pB\n", pc, (void *)pc);
+ pc = *stacktrace_pos++;
+ }
+
+ kvm_err("---- end of nVHE HYP call trace ----\n");
+}
#else /* __KVM_NVHE_HYPERVISOR__ */
DEFINE_PER_CPU(unsigned long [PAGE_SIZE/sizeof(long)], overflow_stack)
__aligned(16);
+
+static int notrace unwind_next(struct task_struct *tsk,
+ struct unwind_state *state)
+{
+ struct stack_info info;
+
+ return __unwind_next(tsk, state, &info);
+}
+
+/**
+ * Saves a hypervisor stacktrace entry (address) to the shared stacktrace page.
+ */
+static bool hyp_save_backtrace_entry(void *arg, unsigned long where)
+{
+ struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
+ unsigned long **stacktrace_pos = (unsigned long **)arg;
+ unsigned long stacktrace_start, stacktrace_end;
+
+ stacktrace_start = (unsigned long)params->stacktrace_hyp_va;
+ stacktrace_end = stacktrace_start + PAGE_SIZE - (2 * sizeof(long));
+
+ if ((unsigned long) *stacktrace_pos > stacktrace_end)
+ return false;
+
+ /* Save the entry to the current pos in stacktrace page */
+ **stacktrace_pos = where;
+
+ /* A zero entry delimits the end of the stacktrace. */
+ *(*stacktrace_pos + 1) = 0UL;
+
+ /* Increment the current pos */
+ ++*stacktrace_pos;
+
+ return true;
+}
+
+/**
+ * Saves hypervisor stacktrace to the shared stacktrace page.
+ */
+noinline notrace void hyp_save_backtrace(void)
+{
+ struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
+ void *stacktrace_start = (void *)params->stacktrace_hyp_va;
+ struct unwind_state state;
+
+ unwind_init(&state, (unsigned long)__builtin_frame_address(0),
+ _THIS_IP_);
+
+ unwind(NULL, &state, hyp_save_backtrace_entry, &stacktrace_start);
+}
+
#endif /* !__KVM_NVHE_HYPERVISOR__ */
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 2e61a987b0d5..f1a6b556ec32 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -17,6 +17,7 @@
#include <asm/kvm_emulate.h>
#include <asm/kvm_mmu.h>
#include <asm/debug-monitors.h>
+#include <asm/stacktrace.h>
#include <asm/traps.h>
#include <kvm/arm_hypercalls.h>
@@ -325,6 +326,9 @@ void __noreturn __cold nvhe_hyp_panic_handler(u64 esr, u64 spsr,
(void *)panic_addr);
}
+ /* Dump the hypervisor stacktrace */
+ hyp_dump_backtrace(hyp_offset);
+
/*
* Hyp has panicked and we're going to handle that by panicking the
* kernel. The kernel offset will be revealed in the panic so we're
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 978f1b94fb25..95d810e86c7d 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -25,6 +25,7 @@
#include <asm/fpsimd.h>
#include <asm/debug-monitors.h>
#include <asm/processor.h>
+#include <asm/stacktrace.h>
#include <nvhe/fixed_config.h>
#include <nvhe/mem_protect.h>
@@ -395,6 +396,9 @@ asmlinkage void __noreturn hyp_panic(void)
__sysreg_restore_state_nvhe(host_ctxt);
}
+ /* Save the hypervisor stacktrace */
+ hyp_save_backtrace();
+
__hyp_do_panic(host_ctxt, spsr, elr, par);
unreachable();
}
--
2.36.0.464.gb9c8b46e94-goog
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH v2 1/5] KVM: arm64: Factor out common stack unwinding logic
2022-05-02 19:12 ` [PATCH v2 1/5] KVM: arm64: Factor out common stack unwinding logic Kalesh Singh
@ 2022-05-04 13:41 ` Mark Brown
0 siblings, 0 replies; 9+ messages in thread
From: Mark Brown @ 2022-05-04 13:41 UTC (permalink / raw)
To: Kalesh Singh
Cc: mark.rutland, will, maz, qperret, tabba, surenb, kernel-team,
James Morse, Alexandru Elisei, Suzuki K Poulose, Catalin Marinas,
Masami Hiramatsu, Peter Collingbourne, Alexei Starovoitov,
Madhavan T. Venkataraman, Andrew Jones, Keir Fraser, Marco Elver,
Kefeng Wang, Zenghui Yu, Ard Biesheuvel, linux-arm-kernel,
kvmarm, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 313 bytes --]
On Mon, May 02, 2022 at 12:12:01PM -0700, Kalesh Singh wrote:
> Factor out the stack unwinding logic common to both the host kernel and
> the nVHE hypersivor into __unwind_next(). This allows for reuse in the
> nVHE hypervisor stack unwinding (later in this series).
Reviewed-by: Mark Brown <broonie@kernel.org>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 2/5] KVM: arm64: Compile stacktrace.nvhe.o
2022-05-02 19:12 ` [PATCH v2 2/5] KVM: arm64: Compile stacktrace.nvhe.o Kalesh Singh
@ 2022-05-04 14:16 ` Mark Brown
2022-05-04 16:02 ` Kalesh Singh
0 siblings, 1 reply; 9+ messages in thread
From: Mark Brown @ 2022-05-04 14:16 UTC (permalink / raw)
To: Kalesh Singh
Cc: mark.rutland, will, maz, qperret, tabba, surenb, kernel-team,
James Morse, Alexandru Elisei, Suzuki K Poulose, Catalin Marinas,
Masami Hiramatsu, Peter Collingbourne, Alexei Starovoitov,
Madhavan T. Venkataraman, Andrew Jones, Marco Elver, Kefeng Wang,
Keir Fraser, Zenghui Yu, linux-arm-kernel, kvmarm, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 830 bytes --]
On Mon, May 02, 2022 at 12:12:02PM -0700, Kalesh Singh wrote:
> Recompile stack unwinding code for use with the nVHE hypervisor. This is
> a preparatory patch that will allow reusing most of the kernel unwinding
> logic in the nVHE hypervisor.
> enum stack_type {
> - STACK_TYPE_UNKNOWN,
> +#ifndef __KVM_NVHE_HYPERVISOR__
> STACK_TYPE_TASK,
> STACK_TYPE_IRQ,
> STACK_TYPE_OVERFLOW,
> STACK_TYPE_SDEI_NORMAL,
> STACK_TYPE_SDEI_CRITICAL,
> +#endif /* !__KVM_NVHE_HYPERVISOR__ */
> + STACK_TYPE_UNKNOWN,
> __NR_STACK_TYPES
> };
I don't immediately see a problem with it but I'm curious as to why
STACK_TYPE_UNKNOWN got moved to the end of the list here? It does mean
that zeroed memory will default to STACK_TYPE_TASK but we're not
actually relying on that. Otherwise
Reviwed-by: Mark Brown <broonie@kernel.org>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v2 2/5] KVM: arm64: Compile stacktrace.nvhe.o
2022-05-04 14:16 ` Mark Brown
@ 2022-05-04 16:02 ` Kalesh Singh
0 siblings, 0 replies; 9+ messages in thread
From: Kalesh Singh @ 2022-05-04 16:02 UTC (permalink / raw)
To: Mark Brown
Cc: Mark Rutland, Will Deacon, Marc Zyngier, Quentin Perret,
Fuad Tabba, Suren Baghdasaryan, Cc: Android Kernel, James Morse,
Alexandru Elisei, Suzuki K Poulose, Catalin Marinas,
Masami Hiramatsu, Peter Collingbourne, Alexei Starovoitov,
Madhavan T. Venkataraman, Andrew Jones, Marco Elver, Kefeng Wang,
Keir Fraser, Zenghui Yu,
moderated list:ARM64 PORT (AARCH64 ARCHITECTURE),
kvmarm, LKML
On Wed, May 4, 2022 at 7:17 AM Mark Brown <broonie@kernel.org> wrote:
>
> On Mon, May 02, 2022 at 12:12:02PM -0700, Kalesh Singh wrote:
>
> > Recompile stack unwinding code for use with the nVHE hypervisor. This is
> > a preparatory patch that will allow reusing most of the kernel unwinding
> > logic in the nVHE hypervisor.
>
> > enum stack_type {
> > - STACK_TYPE_UNKNOWN,
> > +#ifndef __KVM_NVHE_HYPERVISOR__
> > STACK_TYPE_TASK,
> > STACK_TYPE_IRQ,
> > STACK_TYPE_OVERFLOW,
> > STACK_TYPE_SDEI_NORMAL,
> > STACK_TYPE_SDEI_CRITICAL,
> > +#endif /* !__KVM_NVHE_HYPERVISOR__ */
> > + STACK_TYPE_UNKNOWN,
> > __NR_STACK_TYPES
> > };
>
> I don't immediately see a problem with it but I'm curious as to why
> STACK_TYPE_UNKNOWN got moved to the end of the list here? It does mean
> that zeroed memory will default to STACK_TYPE_TASK but we're not
> actually relying on that. Otherwise
Hi Mark. Thanks for the reviews.
STACK_TYPE_UNKNOWN was moved to the end purely to group the common
enum values. Not a functionality change as we don't reply on an
uninitialized stack_type
Thanks,
Kalesh
>
> Reviwed-by: Mark Brown <broonie@kernel.org>
>
> --
> To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com.
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2022-05-04 16:02 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-05-02 19:12 [PATCH v2 0/5] KVM nVHE Hypervisor stack unwinder Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 1/5] KVM: arm64: Factor out common stack unwinding logic Kalesh Singh
2022-05-04 13:41 ` Mark Brown
2022-05-02 19:12 ` [PATCH v2 2/5] KVM: arm64: Compile stacktrace.nvhe.o Kalesh Singh
2022-05-04 14:16 ` Mark Brown
2022-05-04 16:02 ` Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 3/5] KVM: arm64: Add hypervisor overflow stack Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 4/5] KVM: arm64: Allocate shared stacktrace pages Kalesh Singh
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