6 files changed, 184 insertions, 25 deletions

diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index f9fe4dc21b1f..ed5d222e2826 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -12,13 +12,13 @@ HOST_EXTRACFLAGS += -I$(objtree)/include
 lib-objs := clear_page.o copy_page.o memcpy.o memset.o
 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-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
-obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
+	 cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o stacktrace.o
+hyp-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
-obj-y += $(lib-objs)
+hyp-obj-$(CONFIG_DEBUG_LIST) += list_debug.o
+hyp-obj-y += $(lib-objs)
 
 ##
 ## Build rules for compiling nVHE hyp code
@@ -26,9 +26,9 @@ obj-y += $(lib-objs)
 ## file containing all nVHE hyp code and data.
 ##
 
-hyp-obj := $(patsubst %.o,%.nvhe.o,$(obj-y))
+hyp-obj := $(patsubst %.o,%.nvhe.o,$(hyp-obj-y))
 obj-y := kvm_nvhe.o
-extra-y := $(hyp-obj) kvm_nvhe.tmp.o kvm_nvhe.rel.o hyp.lds hyp-reloc.S hyp-reloc.o
+targets += $(hyp-obj) kvm_nvhe.tmp.o kvm_nvhe.rel.o hyp.lds hyp-reloc.S hyp-reloc.o
 
 # 1) Compile all source files to `.nvhe.o` object files. The file extension
 #    avoids file name clashes for files shared with VHE.
diff --git a/arch/arm64/kvm/hyp/nvhe/debug-sr.c b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
index df361d839902..e17455773b98 100644
--- a/arch/arm64/kvm/hyp/nvhe/debug-sr.c
+++ b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
@@ -84,10 +84,10 @@ static void __debug_restore_trace(u64 trfcr_el1)
 void __debug_save_host_buffers_nvhe(struct kvm_vcpu *vcpu)
 {
 	/* Disable and flush SPE data generation */
-	if (vcpu->arch.flags & KVM_ARM64_DEBUG_STATE_SAVE_SPE)
+	if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_SPE))
 		__debug_save_spe(&vcpu->arch.host_debug_state.pmscr_el1);
 	/* Disable and flush Self-Hosted Trace generation */
-	if (vcpu->arch.flags & KVM_ARM64_DEBUG_STATE_SAVE_TRBE)
+	if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRBE))
 		__debug_save_trace(&vcpu->arch.host_debug_state.trfcr_el1);
 }
 
@@ -98,9 +98,9 @@ void __debug_switch_to_guest(struct kvm_vcpu *vcpu)
 
 void __debug_restore_host_buffers_nvhe(struct kvm_vcpu *vcpu)
 {
-	if (vcpu->arch.flags & KVM_ARM64_DEBUG_STATE_SAVE_SPE)
+	if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_SPE))
 		__debug_restore_spe(vcpu->arch.host_debug_state.pmscr_el1);
-	if (vcpu->arch.flags & KVM_ARM64_DEBUG_STATE_SAVE_TRBE)
+	if (vcpu_get_flag(vcpu, DEBUG_STATE_SAVE_TRBE))
 		__debug_restore_trace(vcpu->arch.host_debug_state.trfcr_el1);
 }
 
diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index ea6a397b64a6..b6c0188c4b35 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -177,13 +177,8 @@ 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 + OVERFLOW_STACK_SIZE, x0
 
 	b	hyp_panic_bad_stack
 	ASM_BUG()
diff --git a/arch/arm64/kvm/hyp/nvhe/stacktrace.c b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
new file mode 100644
index 000000000000..58f645ad66bc
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KVM nVHE hypervisor stack tracing support.
+ *
+ * Copyright (C) 2022 Google LLC
+ */
+#include <asm/kvm_asm.h>
+#include <asm/kvm_hyp.h>
+#include <asm/memory.h>
+#include <asm/percpu.h>
+
+DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack)
+	__aligned(16);
+
+DEFINE_PER_CPU(struct kvm_nvhe_stacktrace_info, kvm_stacktrace_info);
+
+/*
+ * hyp_prepare_backtrace - Prepare non-protected nVHE backtrace.
+ *
+ * @fp : frame pointer at which to start the unwinding.
+ * @pc : program counter at which to start the unwinding.
+ *
+ * Save the information needed by the host to unwind the non-protected
+ * nVHE hypervisor stack in EL1.
+ */
+static void hyp_prepare_backtrace(unsigned long fp, unsigned long pc)
+{
+	struct kvm_nvhe_stacktrace_info *stacktrace_info = this_cpu_ptr(&kvm_stacktrace_info);
+	struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
+
+	stacktrace_info->stack_base = (unsigned long)(params->stack_hyp_va - PAGE_SIZE);
+	stacktrace_info->overflow_stack_base = (unsigned long)this_cpu_ptr(overflow_stack);
+	stacktrace_info->fp = fp;
+	stacktrace_info->pc = pc;
+}
+
+#ifdef CONFIG_PROTECTED_NVHE_STACKTRACE
+#include <asm/stacktrace/nvhe.h>
+
+DEFINE_PER_CPU(unsigned long [NVHE_STACKTRACE_SIZE/sizeof(long)], pkvm_stacktrace);
+
+static 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 + OVERFLOW_STACK_SIZE;
+
+	return on_stack(sp, size, low, high, STACK_TYPE_OVERFLOW, info);
+}
+
+static 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);
+}
+
+static bool on_accessible_stack(const struct task_struct *tsk,
+				unsigned long sp, unsigned long size,
+				struct stack_info *info)
+{
+	if (info)
+		info->type = STACK_TYPE_UNKNOWN;
+
+	return (on_overflow_stack(sp, size, info) ||
+		on_hyp_stack(sp, size, info));
+}
+
+static int unwind_next(struct unwind_state *state)
+{
+	struct stack_info info;
+
+	return unwind_next_common(state, &info, on_accessible_stack, NULL);
+}
+
+static void notrace unwind(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(state);
+		if (ret < 0)
+			break;
+	}
+}
+
+/*
+ * pkvm_save_backtrace_entry - Saves a protected nVHE HYP stacktrace entry
+ *
+ * @arg    : index of the entry in the stacktrace buffer
+ * @where  : the program counter corresponding to the stack frame
+ *
+ * Save the return address of a stack frame to the shared stacktrace buffer.
+ * The host can access this shared buffer from EL1 to dump the backtrace.
+ */
+static bool pkvm_save_backtrace_entry(void *arg, unsigned long where)
+{
+	unsigned long *stacktrace = this_cpu_ptr(pkvm_stacktrace);
+	int *idx = (int *)arg;
+
+	/*
+	 * Need 2 free slots: 1 for current entry and 1 for the
+	 * delimiter.
+	 */
+	if (*idx > ARRAY_SIZE(pkvm_stacktrace) - 2)
+		return false;
+
+	stacktrace[*idx] = where;
+	stacktrace[++*idx] = 0UL;
+
+	return true;
+}
+
+/*
+ * pkvm_save_backtrace - Saves the protected nVHE HYP stacktrace
+ *
+ * @fp : frame pointer at which to start the unwinding.
+ * @pc : program counter at which to start the unwinding.
+ *
+ * Save the unwinded stack addresses to the shared stacktrace buffer.
+ * The host can access this shared buffer from EL1 to dump the backtrace.
+ */
+static void pkvm_save_backtrace(unsigned long fp, unsigned long pc)
+{
+	struct unwind_state state;
+	int idx = 0;
+
+	kvm_nvhe_unwind_init(&state, fp, pc);
+
+	unwind(&state, pkvm_save_backtrace_entry, &idx);
+}
+#else /* !CONFIG_PROTECTED_NVHE_STACKTRACE */
+static void pkvm_save_backtrace(unsigned long fp, unsigned long pc)
+{
+}
+#endif /* CONFIG_PROTECTED_NVHE_STACKTRACE */
+
+/*
+ * kvm_nvhe_prepare_backtrace - prepare to dump the nVHE backtrace
+ *
+ * @fp : frame pointer at which to start the unwinding.
+ * @pc : program counter at which to start the unwinding.
+ *
+ * Saves the information needed by the host to dump the nVHE hypervisor
+ * backtrace.
+ */
+void kvm_nvhe_prepare_backtrace(unsigned long fp, unsigned long pc)
+{
+	if (is_protected_kvm_enabled())
+		pkvm_save_backtrace(fp, pc);
+	else
+		hyp_prepare_backtrace(fp, pc);
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 6db801db8f27..9f6385702061 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -34,6 +34,8 @@ DEFINE_PER_CPU(struct kvm_host_data, kvm_host_data);
 DEFINE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
 DEFINE_PER_CPU(unsigned long, kvm_hyp_vector);
 
+extern void kvm_nvhe_prepare_backtrace(unsigned long fp, unsigned long pc);
+
 static void __activate_traps(struct kvm_vcpu *vcpu)
 {
 	u64 val;
@@ -43,7 +45,7 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
 
 	val = vcpu->arch.cptr_el2;
 	val |= CPTR_EL2_TTA | CPTR_EL2_TAM;
-	if (!update_fp_enabled(vcpu)) {
+	if (!guest_owns_fp_regs(vcpu)) {
 		val |= CPTR_EL2_TFP | CPTR_EL2_TZ;
 		__activate_traps_fpsimd32(vcpu);
 	}
@@ -123,7 +125,7 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
 	}
 
 	cptr = CPTR_EL2_DEFAULT;
-	if (vcpu_has_sve(vcpu) && (vcpu->arch.flags & KVM_ARM64_FP_ENABLED))
+	if (vcpu_has_sve(vcpu) && (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED))
 		cptr |= CPTR_EL2_TZ;
 	if (cpus_have_final_cap(ARM64_SME))
 		cptr &= ~CPTR_EL2_TSM;
@@ -335,7 +337,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 
 	__sysreg_restore_state_nvhe(host_ctxt);
 
-	if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED)
+	if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED)
 		__fpsimd_save_fpexc32(vcpu);
 
 	__debug_switch_to_host(vcpu);
@@ -375,6 +377,10 @@ asmlinkage void __noreturn hyp_panic(void)
 		__sysreg_restore_state_nvhe(host_ctxt);
 	}
 
+	/* Prepare to dump kvm nvhe hyp stacktrace */
+	kvm_nvhe_prepare_backtrace((unsigned long)__builtin_frame_address(0),
+				   _THIS_IP_);
+
 	__hyp_do_panic(host_ctxt, spsr, elr, par);
 	unreachable();
 }
@@ -386,5 +392,5 @@ asmlinkage void __noreturn hyp_panic_bad_stack(void)
 
 asmlinkage void kvm_unexpected_el2_exception(void)
 {
-	return __kvm_unexpected_el2_exception();
+	__kvm_unexpected_el2_exception();
 }
diff --git a/arch/arm64/kvm/hyp/nvhe/sys_regs.c b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
index 6b94c3e6ff26..e20fa4475dac 100644
--- a/arch/arm64/kvm/hyp/nvhe/sys_regs.c
+++ b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
@@ -38,9 +38,7 @@ static void inject_undef64(struct kvm_vcpu *vcpu)
 	*vcpu_pc(vcpu) = read_sysreg_el2(SYS_ELR);
 	*vcpu_cpsr(vcpu) = read_sysreg_el2(SYS_SPSR);
 
-	vcpu->arch.flags |= (KVM_ARM64_EXCEPT_AA64_EL1 |
-			     KVM_ARM64_EXCEPT_AA64_ELx_SYNC |
-			     KVM_ARM64_PENDING_EXCEPTION);
+	kvm_pend_exception(vcpu, EXCEPT_AA64_EL1_SYNC);
 
 	__kvm_adjust_pc(vcpu);