Commit 68344037 authored by Vincent Donnefort's avatar Vincent Donnefort Committed by Marc Zyngier
Browse files

KVM: arm64: Fix nVHE stacktrace VA bits mask 



The hypervisor VA space size depends on both the ID map's
(IDMAP_VA_BITS) and the kernel stage-1 (VA_BITS). However, the
hypervisor stacktrace decoding is solely relying on VA_BITS. This is
especially an issue when VA_BITS < IDMAP_VA_BITS (i.e. VA_BITS is
39-bit): the hypervisor may have addresses bigger than the stacktrace is
masking.

Align this mask with hyp_va_bits.

Signed-off-by: default avatarVincent Donnefort <vdonnefort@google.com>
Link: https://lore.kernel.org/r/20250107112821.416591-1-vdonnefort@google.com


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent e8440c1e

arch/arm64/include/asm/kvm_mmu.h

+2 −0
Original line number Diff line number Diff line
@@ -139,6 +139,8 @@ static __always_inline unsigned long __kern_hyp_va(unsigned long v) 


#define kern_hyp_va(v) 	((typeof(v))(__kern_hyp_va((unsigned long)(v))))



extern u32 __hyp_va_bits;



/*

 * We currently support using a VM-specified IPA size. For backward

 * compatibility, the default IPA size is fixed to 40bits.

arch/arm64/kvm/mmu.c

+3 −0
Original line number Diff line number Diff line
@@ -29,6 +29,8 @@ static unsigned long __ro_after_init hyp_idmap_start; 
static unsigned long __ro_after_init hyp_idmap_end;

static phys_addr_t __ro_after_init hyp_idmap_vector;



u32 __ro_after_init __hyp_va_bits;



static unsigned long __ro_after_init io_map_base;



static phys_addr_t __stage2_range_addr_end(phys_addr_t addr, phys_addr_t end,
@@ -2056,6 +2058,7 @@ int __init kvm_mmu_init(u32 *hyp_va_bits) 
		goto out_destroy_pgtable;



	io_map_base = hyp_idmap_start;

	__hyp_va_bits = *hyp_va_bits;

	return 0;



out_destroy_pgtable:

arch/arm64/kvm/stacktrace.c

+2 −1
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <linux/kvm.h>

#include <linux/kvm_host.h>



#include <asm/kvm_mmu.h>

#include <asm/stacktrace/nvhe.h>



static struct stack_info stackinfo_get_overflow(void)
@@ -145,7 +146,7 @@ static void unwind(struct unwind_state *state, 
 */

static bool kvm_nvhe_dump_backtrace_entry(void *arg, unsigned long where)

{

	unsigned long va_mask = GENMASK_ULL(vabits_actual - 1, 0);

	unsigned long va_mask = GENMASK_ULL(__hyp_va_bits - 1, 0);

	unsigned long hyp_offset = (unsigned long)arg;



	/* Mask tags and convert to kern addr */