diff mbox series

[v2,04/14] KVM: arm64/sve: sys_regs: Demote redundant vcpu_has_sve() checks to WARNs

Message ID 1555603631-8107-5-git-send-email-Dave.Martin@arm.com (mailing list archive)
State Mainlined, archived
Commit 700698a8a9741063c9804c7bce2dbec6c8d69f3d
Headers show
Series KVM: arm64: SVE cleanups | expand

Commit Message

Dave Martin April 18, 2019, 4:07 p.m. UTC 
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>
---
 arch/arm64/kvm/sys_regs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 09e9b06..7046c76 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1144,7 +1144,7 @@  static int get_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
 {
 	u64 val;
 
-	if (!vcpu_has_sve(vcpu))
+	if (WARN_ON(!vcpu_has_sve(vcpu)))
 		return -ENOENT;
 
 	val = guest_id_aa64zfr0_el1(vcpu);
@@ -1159,7 +1159,7 @@  static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
 	int err;
 	u64 val;
 
-	if (!vcpu_has_sve(vcpu))
+	if (WARN_ON(!vcpu_has_sve(vcpu)))
 		return -ENOENT;
 
 	err = reg_from_user(&val, uaddr, id);