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KVM: arm64: Hide CNTHV_*_EL2 from userspace for nVHE guests

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Although we correctly UNDEF any CNTHV_*_EL2 access from the guest
when E2H==0, we still expose these registers to userspace, which
is a bad idea.

Drop the ad-hoc UNDEF injection and switch to a .visibility()
callback which will also hide the register from userspace.

Fixes: 0e45981028 ("KVM: arm64: timer: Don't adjust the EL2 virtual timer offset")
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2025-09-29 17:04:45 +01:00
parent 164ecbf73c
commit 4cab5c857d
1 changed files with 13 additions and 13 deletions
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26
arch/arm64/kvm/sys_regs.c
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@ -1594,16 +1594,6 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu,
return true;
}
static bool access_hv_timer(struct kvm_vcpu *vcpu,
struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
if (!vcpu_el2_e2h_is_set(vcpu))
return undef_access(vcpu, p, r);
return access_arch_timer(vcpu, p, r);
}
static s64 kvm_arm64_ftr_safe_value(u32 id, const struct arm64_ftr_bits *ftrp,
s64 new, s64 cur)
{
@ -2831,6 +2821,16 @@ static unsigned int s1pie_el2_visibility(const struct kvm_vcpu *vcpu,
return __el2_visibility(vcpu, rd, s1pie_visibility);
}
static unsigned int cnthv_visibility(const struct kvm_vcpu *vcpu,
const struct sys_reg_desc *rd)
{
if (vcpu_has_nv(vcpu) &&
!vcpu_has_feature(vcpu, KVM_ARM_VCPU_HAS_EL2_E2H0))
return 0;
return REG_HIDDEN;
}
static bool access_mdcr(struct kvm_vcpu *vcpu,
struct sys_reg_params *p,
const struct sys_reg_desc *r)
@ -3691,9 +3691,9 @@ static const struct sys_reg_desc sys_reg_descs[] = {
EL2_REG(CNTHP_CTL_EL2, access_arch_timer, reset_val, 0),
EL2_REG(CNTHP_CVAL_EL2, access_arch_timer, reset_val, 0),
{ SYS_DESC(SYS_CNTHV_TVAL_EL2), access_hv_timer },
EL2_REG(CNTHV_CTL_EL2, access_hv_timer, reset_val, 0),
EL2_REG(CNTHV_CVAL_EL2, access_hv_timer, reset_val, 0),
{ SYS_DESC(SYS_CNTHV_TVAL_EL2), access_arch_timer, .visibility = cnthv_visibility },
EL2_REG_FILTERED(CNTHV_CTL_EL2, access_arch_timer, reset_val, 0, cnthv_visibility),
EL2_REG_FILTERED(CNTHV_CVAL_EL2, access_arch_timer, reset_val, 0, cnthv_visibility),
{ SYS_DESC(SYS_CNTKCTL_EL12), access_cntkctl_el12 },