KVM: arm64: Move FP state ownership from flag to a tristate

The KVM FP code uses a pair of flags to denote three states:

- FP_ENABLED set: the guest owns the FP state
- FP_HOST set: the host owns the FP state
- FP_ENABLED and FP_HOST clear: nobody owns the FP state at all

and both flags set is an illegal state, which nothing ever checks
for...

As it turns out, this isn't really a good match for flags, and
we'd be better off if this was a simpler tristate, each state
having a name that actually reflect the state:

- FP_STATE_FREE
- FP_STATE_HOST_OWNED
- FP_STATE_GUEST_OWNED

Kill the two flags, and move over to an enum encoding these
three states. This results in less confusing code, and less risk of
ending up in the uncharted territory of a 4th state if we forget
to clear one of the two flags.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Reiji Watanabe <reijiw@google.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 63103cc1bdc4..372c5642cfab 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -325,6 +325,13 @@ struct kvm_vcpu_arch {
 	/* Exception Information */
 	struct kvm_vcpu_fault_info fault;
 
+	/* Ownership of the FP regs */
+	enum {
+		FP_STATE_FREE,
+		FP_STATE_HOST_OWNED,
+		FP_STATE_GUEST_OWNED,
+	} fp_state;
+
 	/* Miscellaneous vcpu state flags */
 	u64 flags;
 
@@ -430,8 +437,6 @@ struct kvm_vcpu_arch {
 
 /* vcpu_arch flags field values: */
 #define KVM_ARM64_DEBUG_DIRTY		(1 << 0)
-#define KVM_ARM64_FP_ENABLED		(1 << 1) /* guest FP regs loaded */
-#define KVM_ARM64_FP_HOST		(1 << 2) /* host FP regs loaded */
 #define KVM_ARM64_HOST_SVE_ENABLED	(1 << 4) /* SVE enabled for EL0 */
 #define KVM_ARM64_GUEST_HAS_SVE		(1 << 5) /* SVE exposed to guest */
 #define KVM_ARM64_VCPU_SVE_FINALIZED	(1 << 6) /* SVE config completed */