From: Andrew Jones drjones@redhat.com

ID registers are RAZ until they've been allocated a purpose, but that doesn't mean they should be removed from the KVM_GET_REG_LIST list. So far we only have one register, SYS_ID_AA64ZFR0_EL1, that is hidden from userspace when its function, SVE, is not present.

Expose SYS_ID_AA64ZFR0_EL1 to userspace as RAZ when SVE is not implemented. Removing the userspace visibility checks is enough to reexpose it, as it will already return zero to userspace when SVE is not present. The register already behaves as RAZ for the guest when SVE is not present.

Fixes: 73433762fcae ("KVM: arm64/sve: System register context switch and access support") Reported-by: 张东旭 xu910121@sina.com Signed-off-by: Andrew Jones drjones@redhat.com Signed-off-by: Marc Zyngier maz@kernel.org Cc: stable@vger.kernel.org#v5.2+ Link: https://lore.kernel.org/r/20201105091022.15373-2-drjones@redhat.com --- arch/arm64/kvm/sys_regs.c | 18 +----------------- 1 file changed, 1 insertion(+), 17 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 983994f01a63..3af306e6b9cd 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1193,16 +1193,6 @@ static unsigned int sve_visibility(const struct kvm_vcpu *vcpu, return REG_HIDDEN_USER | REG_HIDDEN_GUEST; }

-/* Visibility overrides for SVE-specific ID registers */ -static unsigned int sve_id_visibility(const struct kvm_vcpu *vcpu, - const struct sys_reg_desc *rd) -{ - if (vcpu_has_sve(vcpu)) - return 0; - - return REG_HIDDEN_USER; -} - /* Generate the emulated ID_AA64ZFR0_EL1 value exposed to the guest */ static u64 guest_id_aa64zfr0_el1(const struct kvm_vcpu *vcpu) { @@ -1229,9 +1219,6 @@ static int get_id_aa64zfr0_el1(struct kvm_vcpu *vcpu, { u64 val;

- if (WARN_ON(!vcpu_has_sve(vcpu))) - return -ENOENT; - val = guest_id_aa64zfr0_el1(vcpu); return reg_to_user(uaddr, &val, reg->id); } @@ -1244,9 +1231,6 @@ static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu, int err; u64 val;

- if (WARN_ON(!vcpu_has_sve(vcpu))) - return -ENOENT; - err = reg_from_user(&val, uaddr, id); if (err) return err; @@ -1509,7 +1493,7 @@ static const struct sys_reg_desc sys_reg_descs[] = { ID_SANITISED(ID_AA64PFR1_EL1), ID_UNALLOCATED(4,2), ID_UNALLOCATED(4,3), - { SYS_DESC(SYS_ID_AA64ZFR0_EL1), access_id_aa64zfr0_el1, .get_user = get_id_aa64zfr0_el1, .set_user = set_id_aa64zfr0_el1, .visibility = sve_id_visibility }, + { SYS_DESC(SYS_ID_AA64ZFR0_EL1), access_id_aa64zfr0_el1, .get_user = get_id_aa64zfr0_el1, .set_user = set_id_aa64zfr0_el1, }, ID_UNALLOCATED(4,5), ID_UNALLOCATED(4,6), ID_UNALLOCATED(4,7),