KVM: arm64: Convert timer offset VA when accessed in HYP code
Marc Zyngier
maintainerPATCH 1/1 KVM: arm64: Convert timer offset VA when accessed in HYP code
Now that EL2 has gained some early timer emulation, it accesses the offsets pointed to by the timer structure, both of which live in the KVM structure.
Of course, these are *kernel* pointers, so the dereferencing of these pointers in non-kernel code must be itself be offset.
Given switch.h its own version of timer_get_offset() and use that instead.
--- arch/arm64/kvm/hyp/include/hyp/switch.h | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)
arch/arm64/kvm/hyp/include/hyp/switch.h +14 -1
@@ -581,9 +581,22 @@ static inline bool handle_tx2_tvm(struct kvm_vcpu *vcpu)return true; } +/* Open-coded version of timer_get_offset() to allow for kern_hyp_va() */ +static inline u64 hyp_timer_get_offset (struct arch_timer_context *ctxt) +{ +u64 offset =0 ; + +if (ctxt->offset.vm_offset) + offset += *kern_hyp_va (ctxt->offset.vm_offset); +if (ctxt->offset.vcpu_offset) + offset += *kern_hyp_va (ctxt->offset.vcpu_offset); + +return offset; +} +static inline u64 compute_counter_value (struct arch_timer_context *ctxt) { -return arch_timer_read_cntpct_el0 () -timer_get_offset (ctxt); +return arch_timer_read_cntpct_el0 () -hyp_timer_get_offset (ctxt); }static bool kvm_handle_cntxct (struct kvm_vcpu *vcpu)
Signature · 1 line
2.39.2
Quoted 7 lines · Marc Zyngier
Now that EL2 has gained some early timer emulation, it accesses the offsets pointed to by the timer structure, both of which live in the KVM structure.
Of course, these are *kernel* pointers, so the dereferencing of these pointers in non-kernel code must be itself be offset.
Quoted 6 lines
Given
switch.hits own version oftimer_get_offset()and use that instead.Fixes b86fc215dc26d ("KVM: arm64: Handle counter access early in non-HYP context")Signed-off-by Marc Zyngier <[email protected]>
Quoted 8 lines · Marc Zyngier' via lkft
Now that EL2 has gained some early timer emulation, it accesses the offsets pointed to by the timer structure, both of which live in the KVM structure.
Of course, these are *kernel* pointers, so the dereferencing of these pointers in non-kernel code must be itself be offset.
Quoted 6 lines
Given
switch.hits own version oftimer_get_offset()and use that instead.Fixes b86fc215dc26d ("KVM: arm64: Handle counter access early in non-HYP context")Signed-off-by Marc Zyngier <[email protected]>
Build this patch ontop of next-20250212 and ran kvm-unit-tests on a rockpi4. And it ran fine without any kernel panic.
Cheers,
Anders
Quoted 8 lines · Marc Zyngier
Now that EL2 has gained some early timer emulation, it accesses the offsets pointed to by the timer structure, both of which live in the KVM structure.
Of course, these are *kernel* pointers, so the dereferencing of these pointers in non-kernel code must be itself be offset.
[...]
Applied to fixes, thanks!
[1/1] KVM: arm64: Convert timer offset VA when accessed in HYP code
commit: 18ec0be672a4a27aa045cf692eeb1e180a202e0c
Cheers,
M.
Signature · 1 line
Without deviation from the norm, progress is not possible.