KVM: arm64: Refactor checks for FP state ownership

To avoid direct comparison against the fp_owner enum, add a new
function that performs the check, host_owns_fp_regs(), to
complement the existing guest_owns_fp_regs().

To check for fpsimd state ownership, use the helpers instead of
directly using the enums.

No functional change intended.

Suggested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240423150538.2103045-4-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

Author: Fuad Tabba

arch/arm64/include/asm/kvm_emulate.h

@@ -587,16 +587,14 @@ static __always_inline u64 kvm_get_reset_cptr_el2(struct kvm_vcpu *vcpu)
 	} else if (has_hvhe()) {
 		val = (CPACR_EL1_FPEN_EL0EN | CPACR_EL1_FPEN_EL1EN);
 
-		if (!vcpu_has_sve(vcpu) ||
-		    (*host_data_ptr(fp_owner) != FP_STATE_GUEST_OWNED))
+		if (!vcpu_has_sve(vcpu) || !guest_owns_fp_regs())
 			val |= CPACR_EL1_ZEN_EL1EN | CPACR_EL1_ZEN_EL0EN;
 		if (cpus_have_final_cap(ARM64_SME))
 			val |= CPACR_EL1_SMEN_EL1EN | CPACR_EL1_SMEN_EL0EN;
 	} else {
 		val = CPTR_NVHE_EL2_RES1;
 
-		if (vcpu_has_sve(vcpu) &&
-		    (*host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED))
+		if (vcpu_has_sve(vcpu) && guest_owns_fp_regs())
 			val |= CPTR_EL2_TZ;
 		if (cpus_have_final_cap(ARM64_SME))
 			val &= ~CPTR_EL2_TSM;

arch/arm64/include/asm/kvm_host.h

@@ -1213,6 +1213,12 @@ static inline bool guest_owns_fp_regs(void)
 	return *host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED;
 }
 
+/* Check whether the FP regs are owned by the host */
+static inline bool host_owns_fp_regs(void)
+{
+	return *host_data_ptr(fp_owner) == FP_STATE_HOST_OWNED;
+}
+
 static inline void kvm_init_host_cpu_context(struct kvm_cpu_context *cpu_ctxt)
 {
 	/* The host's MPIDR is immutable, so let's set it up at boot time */

arch/arm64/kvm/fpsimd.c

@@ -141,8 +141,7 @@ void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu)
 
 	WARN_ON_ONCE(!irqs_disabled());
 
-	if (*host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED) {
-
+	if (guest_owns_fp_regs()) {
 		/*
 		 * Currently we do not support SME guests so SVCR is
 		 * always 0 and we just need a variable to point to.
@@ -195,7 +194,7 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 		isb();
 	}
 
-	if (*host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED) {
+	if (guest_owns_fp_regs()) {
 		if (vcpu_has_sve(vcpu)) {
 			__vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);
 

arch/arm64/kvm/hyp/include/hyp/switch.h

@@ -370,7 +370,7 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
 	isb();
 
 	/* Write out the host state if it's in the registers */
-	if (*host_data_ptr(fp_owner) == FP_STATE_HOST_OWNED)
+	if (host_owns_fp_regs())
 		__fpsimd_save_state(*host_data_ptr(fpsimd_state));
 
 	/* Restore the guest state */

arch/arm64/kvm/hyp/nvhe/switch.c

@@ -337,7 +337,7 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 
 	__sysreg_restore_state_nvhe(host_ctxt);
 
-	if (*host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED)
+	if (guest_owns_fp_regs())
 		__fpsimd_save_fpexc32(vcpu);
 
 	__debug_switch_to_host(vcpu);

arch/arm64/kvm/hyp/vhe/switch.c

@@ -258,7 +258,7 @@ static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
 
 	sysreg_restore_host_state_vhe(host_ctxt);
 
-	if (*host_data_ptr(fp_owner) == FP_STATE_GUEST_OWNED)
+	if (guest_owns_fp_regs())
 		__fpsimd_save_fpexc32(vcpu);
 
 	__debug_switch_to_host(vcpu);