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KVM: arm64/sve: sys_regs: Demote redundant vcpu_has_sve() checks to WARNs 

Because of the logic in kvm_arm_sys_reg_{get,set}_reg() and
sve_id_visibility(), we should never call
{get,set}_id_aa64zfr0_el1() for a vcpu where !vcpu_has_sve(vcpu).

To avoid the code giving the impression that it is valid for these
functions to be called in this situation, and to help the compiler
make the right optimisation decisions, this patch adds WARN_ON()
for these cases.

Given the way the logic is spread out, this seems preferable to
dropping the checks altogether.

Suggested-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Dave Martin 2019-04-05 16:35:50 +01:00 committed by Marc Zyngier
parent 0323e027df
commit 700698a8a9
1 changed files with 2 additions and 2 deletions
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4
arch/arm64/kvm/sys_regs.c
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@ -1144,7 +1144,7 @@ static int get_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
{ {
u64 val; u64 val;
if (!vcpu_has_sve(vcpu)) if (WARN_ON(!vcpu_has_sve(vcpu)))
return -ENOENT; return -ENOENT;
val = guest_id_aa64zfr0_el1(vcpu); val = guest_id_aa64zfr0_el1(vcpu);
@ -1159,7 +1159,7 @@ static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
int err; int err;
u64 val; u64 val;
if (!vcpu_has_sve(vcpu)) if (WARN_ON(!vcpu_has_sve(vcpu)))
return -ENOENT; return -ENOENT;
err = reg_from_user(&val, uaddr, id); err = reg_from_user(&val, uaddr, id);