Commit db129d48 authored by Kalesh Singh's avatar Kalesh Singh Committed by Marc Zyngier
Browse files

KVM: arm64: Implement non-protected nVHE hyp stack unwinder 



Implements the common framework necessary for unwind() to work
for non-protected nVHE mode:
    - on_accessible_stack()
    - on_overflow_stack()
    - unwind_next()

Non-protected nVHE unwind() is used to unwind and dump the hypervisor
stacktrace by the host in EL1

Signed-off-by: default avatarKalesh Singh <kaleshsingh@google.com>
Reviewed-by: default avatarFuad Tabba <tabba@google.com>
Tested-by: default avatarFuad Tabba <tabba@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-11-kaleshsingh@google.com
parent 879e5ac7

arch/arm64/include/asm/stacktrace/common.h

+2 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ enum stack_type { 
	STACK_TYPE_OVERFLOW,

	STACK_TYPE_SDEI_NORMAL,

	STACK_TYPE_SDEI_CRITICAL,

	STACK_TYPE_HYP,

	__NR_STACK_TYPES

};
@@ -186,6 +187,7 @@ static inline int unwind_next_common(struct unwind_state *state, 
	 *

	 * 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

arch/arm64/include/asm/stacktrace/nvhe.h

+74 −2
Original line number Diff line number Diff line
@@ -16,10 +16,19 @@ 


#include <asm/stacktrace/common.h>



static inline bool on_hyp_stack(unsigned long sp, unsigned long size,

				struct stack_info *info);



static inline bool on_accessible_stack(const struct task_struct *tsk,

				       unsigned long sp, unsigned long size,

				       struct stack_info *info)

{

	if (on_accessible_stack_common(tsk, sp, size, info))

		return true;



	if (on_hyp_stack(sp, size, info))

		return true;



	return false;

}
@@ -31,15 +40,78 @@ static inline bool on_accessible_stack(const struct task_struct *tsk, 
 * (by the host in EL1).

 */



DECLARE_KVM_NVHE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);

DECLARE_KVM_NVHE_PER_CPU(struct kvm_nvhe_stacktrace_info, kvm_stacktrace_info);

DECLARE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);



/*

 * kvm_nvhe_stack_kern_va - Convert KVM nVHE HYP stack addresses to a kernel VAs

 *

 * The nVHE hypervisor stack is mapped in the flexible 'private' VA range, to

 * allow for guard pages below the stack. Consequently, the fixed offset address

 * translation macros won't work here.

 *

 * The kernel VA is calculated as an offset from the kernel VA of the hypervisor

 * stack base.

 *

 * Returns true on success and updates @addr to its corresponding kernel VA;

 * otherwise returns false.

 */

static inline bool kvm_nvhe_stack_kern_va(unsigned long *addr,

					  enum stack_type type)

{

	struct kvm_nvhe_stacktrace_info *stacktrace_info;

	unsigned long hyp_base, kern_base, hyp_offset;



	stacktrace_info = this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);



	switch (type) {

	case STACK_TYPE_HYP:

		kern_base = (unsigned long)*this_cpu_ptr(&kvm_arm_hyp_stack_page);

		hyp_base = (unsigned long)stacktrace_info->stack_base;

		break;

	case STACK_TYPE_OVERFLOW:

		kern_base = (unsigned long)this_cpu_ptr_nvhe_sym(overflow_stack);

		hyp_base = (unsigned long)stacktrace_info->overflow_stack_base;

		break;

	default:

		return false;

	}



	hyp_offset = *addr - hyp_base;



	*addr = kern_base + hyp_offset;



	return true;

}



static inline bool on_overflow_stack(unsigned long sp, unsigned long size,

				     struct stack_info *info)

{

	return false;

	struct kvm_nvhe_stacktrace_info *stacktrace_info

				= this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);

	unsigned long low = (unsigned long)stacktrace_info->overflow_stack_base;

	unsigned long high = low + OVERFLOW_STACK_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_stacktrace_info *stacktrace_info

				= this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);

	unsigned long low = (unsigned long)stacktrace_info->stack_base;

	unsigned long high = low + PAGE_SIZE;



	return on_stack(sp, size, low, high, STACK_TYPE_HYP, info);

}



static inline int notrace unwind_next(struct unwind_state *state)

{

	return 0;

	struct stack_info info;



	return unwind_next_common(state, &info, kvm_nvhe_stack_kern_va);

}

NOKPROBE_SYMBOL(unwind_next);

arch/arm64/kvm/arm.c

+1 −1
Original line number Diff line number Diff line
@@ -49,7 +49,7 @@ 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_stack_page);

unsigned long kvm_arm_hyp_percpu_base[NR_CPUS];

DECLARE_KVM_NVHE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);